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c906108c | 1 | \input texinfo @c -*-texinfo-*- |
29e57380 | 2 | @c Copyright 1988-2001 |
c906108c SS |
3 | @c Free Software Foundation, Inc. |
4 | @c | |
5d161b24 | 5 | @c %**start of header |
c906108c SS |
6 | @c makeinfo ignores cmds prev to setfilename, so its arg cannot make use |
7 | @c of @set vars. However, you can override filename with makeinfo -o. | |
8 | @setfilename gdb.info | |
9 | @c | |
10 | @include gdb-cfg.texi | |
11 | @c | |
c906108c | 12 | @settitle Debugging with @value{GDBN} |
c906108c SS |
13 | @setchapternewpage odd |
14 | @c %**end of header | |
15 | ||
16 | @iftex | |
17 | @c @smallbook | |
18 | @c @cropmarks | |
19 | @end iftex | |
20 | ||
21 | @finalout | |
22 | @syncodeindex ky cp | |
23 | ||
41afff9a | 24 | @c readline appendices use @vindex, @findex and @ftable, |
48e934c6 | 25 | @c annotate.texi and gdbmi use @findex. |
c906108c | 26 | @syncodeindex vr cp |
41afff9a | 27 | @syncodeindex fn cp |
c906108c SS |
28 | |
29 | @c !!set GDB manual's edition---not the same as GDB version! | |
6d2ebf8b | 30 | @set EDITION Eighth |
c906108c SS |
31 | |
32 | @c !!set GDB manual's revision date | |
6d2ebf8b | 33 | @set DATE March 2000 |
c906108c | 34 | |
6d2ebf8b | 35 | @c THIS MANUAL REQUIRES TEXINFO 3.12 OR LATER. |
c906108c | 36 | |
c906108c | 37 | @c This is a dir.info fragment to support semi-automated addition of |
6d2ebf8b | 38 | @c manuals to an info tree. |
96a2c332 SS |
39 | @dircategory Programming & development tools. |
40 | @direntry | |
c906108c | 41 | * Gdb: (gdb). The @sc{gnu} debugger. |
96a2c332 SS |
42 | @end direntry |
43 | ||
c906108c SS |
44 | @ifinfo |
45 | This file documents the @sc{gnu} debugger @value{GDBN}. | |
46 | ||
47 | ||
5d161b24 | 48 | This is the @value{EDITION} Edition, @value{DATE}, |
c906108c SS |
49 | of @cite{Debugging with @value{GDBN}: the @sc{gnu} Source-Level Debugger} |
50 | for @value{GDBN} Version @value{GDBVN}. | |
51 | ||
6d2ebf8b | 52 | Copyright (C) 1988-2000 Free Software Foundation, Inc. |
c906108c SS |
53 | |
54 | Permission is granted to make and distribute verbatim copies of | |
55 | this manual provided the copyright notice and this permission notice | |
56 | are preserved on all copies. | |
57 | ||
58 | @ignore | |
59 | Permission is granted to process this file through TeX and print the | |
60 | results, provided the printed document carries copying permission | |
61 | notice identical to this one except for the removal of this paragraph | |
62 | (this paragraph not being relevant to the printed manual). | |
63 | ||
64 | @end ignore | |
65 | Permission is granted to copy and distribute modified versions of this | |
66 | manual under the conditions for verbatim copying, provided also that the | |
67 | entire resulting derived work is distributed under the terms of a | |
68 | permission notice identical to this one. | |
69 | ||
70 | Permission is granted to copy and distribute translations of this manual | |
71 | into another language, under the above conditions for modified versions. | |
72 | @end ifinfo | |
73 | ||
74 | @titlepage | |
75 | @title Debugging with @value{GDBN} | |
76 | @subtitle The @sc{gnu} Source-Level Debugger | |
c906108c | 77 | @sp 1 |
c906108c SS |
78 | @subtitle @value{EDITION} Edition, for @value{GDBN} version @value{GDBVN} |
79 | @subtitle @value{DATE} | |
9e9c5ae7 | 80 | @author Richard Stallman, Roland Pesch, Stan Shebs, et al. |
c906108c | 81 | @page |
c906108c SS |
82 | @tex |
83 | {\parskip=0pt | |
53a5351d | 84 | \hfill (Send bugs and comments on @value{GDBN} to bug-gdb\@gnu.org.)\par |
c906108c SS |
85 | \hfill {\it Debugging with @value{GDBN}}\par |
86 | \hfill \TeX{}info \texinfoversion\par | |
87 | } | |
88 | @end tex | |
53a5351d | 89 | |
c906108c | 90 | @vskip 0pt plus 1filll |
6d2ebf8b | 91 | Copyright @copyright{} 1988-2000 Free Software Foundation, Inc. |
c906108c | 92 | @sp 2 |
c906108c SS |
93 | Published by the Free Software Foundation @* |
94 | 59 Temple Place - Suite 330, @* | |
95 | Boston, MA 02111-1307 USA @* | |
6d2ebf8b SS |
96 | ISBN 1-882114-77-9 @* |
97 | ||
c906108c SS |
98 | Permission is granted to make and distribute verbatim copies of |
99 | this manual provided the copyright notice and this permission notice | |
100 | are preserved on all copies. | |
101 | ||
102 | Permission is granted to copy and distribute modified versions of this | |
103 | manual under the conditions for verbatim copying, provided also that the | |
104 | entire resulting derived work is distributed under the terms of a | |
105 | permission notice identical to this one. | |
106 | ||
107 | Permission is granted to copy and distribute translations of this manual | |
108 | into another language, under the above conditions for modified versions. | |
109 | @end titlepage | |
110 | @page | |
111 | ||
b9deaee7 | 112 | @ifinfo |
6d2ebf8b SS |
113 | @node Top, Summary, (dir), (dir) |
114 | ||
c906108c SS |
115 | @top Debugging with @value{GDBN} |
116 | ||
117 | This file describes @value{GDBN}, the @sc{gnu} symbolic debugger. | |
118 | ||
5d161b24 | 119 | This is the @value{EDITION} Edition, @value{DATE}, for @value{GDBN} Version |
c906108c SS |
120 | @value{GDBVN}. |
121 | ||
6d2ebf8b SS |
122 | Copyright (C) 1988-2000 Free Software Foundation, Inc. |
123 | ||
124 | @menu | |
125 | * Summary:: Summary of @value{GDBN} | |
126 | * Sample Session:: A sample @value{GDBN} session | |
127 | ||
128 | * Invocation:: Getting in and out of @value{GDBN} | |
129 | * Commands:: @value{GDBN} commands | |
130 | * Running:: Running programs under @value{GDBN} | |
131 | * Stopping:: Stopping and continuing | |
132 | * Stack:: Examining the stack | |
133 | * Source:: Examining source files | |
134 | * Data:: Examining data | |
135 | ||
136 | * Languages:: Using @value{GDBN} with different languages | |
137 | ||
138 | * Symbols:: Examining the symbol table | |
139 | * Altering:: Altering execution | |
140 | * GDB Files:: @value{GDBN} files | |
141 | * Targets:: Specifying a debugging target | |
142 | * Configurations:: Configuration-specific information | |
143 | * Controlling GDB:: Controlling @value{GDBN} | |
144 | * Sequences:: Canned sequences of commands | |
145 | * Emacs:: Using @value{GDBN} under @sc{gnu} Emacs | |
146 | * Annotations:: @value{GDBN}'s annotation interface. | |
7162c0ca | 147 | * GDB/MI:: @value{GDBN}'s Machine Interface. |
6d2ebf8b SS |
148 | |
149 | * GDB Bugs:: Reporting bugs in @value{GDBN} | |
150 | * Formatting Documentation:: How to format and print @value{GDBN} documentation | |
151 | ||
152 | * Command Line Editing:: Command Line Editing | |
153 | * Using History Interactively:: Using History Interactively | |
154 | * Installing GDB:: Installing GDB | |
155 | * Index:: Index | |
156 | @end menu | |
157 | ||
b9deaee7 | 158 | @end ifinfo |
6d2ebf8b SS |
159 | |
160 | @c the replication sucks, but this avoids a texinfo 3.12 lameness | |
161 | ||
162 | @ifhtml | |
163 | @node Top | |
164 | ||
165 | @top Debugging with @value{GDBN} | |
166 | ||
167 | This file describes @value{GDBN}, the @sc{gnu} symbolic debugger. | |
168 | ||
169 | This is the @value{EDITION} Edition, @value{DATE}, for @value{GDBN} Version | |
170 | @value{GDBVN}. | |
171 | ||
172 | Copyright (C) 1988-2000 Free Software Foundation, Inc. | |
173 | ||
c906108c SS |
174 | @menu |
175 | * Summary:: Summary of @value{GDBN} | |
c906108c | 176 | * Sample Session:: A sample @value{GDBN} session |
c906108c SS |
177 | |
178 | * Invocation:: Getting in and out of @value{GDBN} | |
179 | * Commands:: @value{GDBN} commands | |
180 | * Running:: Running programs under @value{GDBN} | |
181 | * Stopping:: Stopping and continuing | |
182 | * Stack:: Examining the stack | |
183 | * Source:: Examining source files | |
184 | * Data:: Examining data | |
c906108c | 185 | |
7a292a7a | 186 | * Languages:: Using @value{GDBN} with different languages |
c906108c SS |
187 | |
188 | * Symbols:: Examining the symbol table | |
189 | * Altering:: Altering execution | |
190 | * GDB Files:: @value{GDBN} files | |
191 | * Targets:: Specifying a debugging target | |
104c1213 | 192 | * Configurations:: Configuration-specific information |
c906108c SS |
193 | * Controlling GDB:: Controlling @value{GDBN} |
194 | * Sequences:: Canned sequences of commands | |
c906108c | 195 | * Emacs:: Using @value{GDBN} under @sc{gnu} Emacs |
6d2ebf8b | 196 | * Annotations:: @value{GDBN}'s annotation interface. |
c906108c SS |
197 | |
198 | * GDB Bugs:: Reporting bugs in @value{GDBN} | |
c906108c | 199 | * Formatting Documentation:: How to format and print @value{GDBN} documentation |
c906108c SS |
200 | |
201 | * Command Line Editing:: Command Line Editing | |
202 | * Using History Interactively:: Using History Interactively | |
203 | * Installing GDB:: Installing GDB | |
204 | * Index:: Index | |
c906108c SS |
205 | @end menu |
206 | ||
6d2ebf8b SS |
207 | @end ifhtml |
208 | ||
449f3b6c AC |
209 | @c TeX can handle the contents at the start but makeinfo 3.12 can not |
210 | @iftex | |
211 | @contents | |
212 | @end iftex | |
213 | ||
6d2ebf8b | 214 | @node Summary |
c906108c SS |
215 | @unnumbered Summary of @value{GDBN} |
216 | ||
217 | The purpose of a debugger such as @value{GDBN} is to allow you to see what is | |
218 | going on ``inside'' another program while it executes---or what another | |
219 | program was doing at the moment it crashed. | |
220 | ||
221 | @value{GDBN} can do four main kinds of things (plus other things in support of | |
222 | these) to help you catch bugs in the act: | |
223 | ||
224 | @itemize @bullet | |
225 | @item | |
226 | Start your program, specifying anything that might affect its behavior. | |
227 | ||
228 | @item | |
229 | Make your program stop on specified conditions. | |
230 | ||
231 | @item | |
232 | Examine what has happened, when your program has stopped. | |
233 | ||
234 | @item | |
235 | Change things in your program, so you can experiment with correcting the | |
236 | effects of one bug and go on to learn about another. | |
237 | @end itemize | |
238 | ||
cce74817 | 239 | You can use @value{GDBN} to debug programs written in C and C++. |
c906108c | 240 | For more information, see @ref{Support,,Supported languages}. |
c906108c SS |
241 | For more information, see @ref{C,,C and C++}. |
242 | ||
cce74817 JM |
243 | @cindex Chill |
244 | @cindex Modula-2 | |
c906108c | 245 | Support for Modula-2 and Chill is partial. For information on Modula-2, |
cce74817 | 246 | see @ref{Modula-2,,Modula-2}. For information on Chill, see @ref{Chill}. |
c906108c | 247 | |
cce74817 JM |
248 | @cindex Pascal |
249 | Debugging Pascal programs which use sets, subranges, file variables, or | |
250 | nested functions does not currently work. @value{GDBN} does not support | |
251 | entering expressions, printing values, or similar features using Pascal | |
252 | syntax. | |
c906108c | 253 | |
c906108c SS |
254 | @cindex Fortran |
255 | @value{GDBN} can be used to debug programs written in Fortran, although | |
53a5351d | 256 | it may be necessary to refer to some variables with a trailing |
cce74817 | 257 | underscore. |
c906108c | 258 | |
c906108c SS |
259 | @menu |
260 | * Free Software:: Freely redistributable software | |
261 | * Contributors:: Contributors to GDB | |
262 | @end menu | |
263 | ||
6d2ebf8b | 264 | @node Free Software |
c906108c SS |
265 | @unnumberedsec Free software |
266 | ||
5d161b24 | 267 | @value{GDBN} is @dfn{free software}, protected by the @sc{gnu} |
c906108c SS |
268 | General Public License |
269 | (GPL). The GPL gives you the freedom to copy or adapt a licensed | |
270 | program---but every person getting a copy also gets with it the | |
271 | freedom to modify that copy (which means that they must get access to | |
272 | the source code), and the freedom to distribute further copies. | |
273 | Typical software companies use copyrights to limit your freedoms; the | |
274 | Free Software Foundation uses the GPL to preserve these freedoms. | |
275 | ||
276 | Fundamentally, the General Public License is a license which says that | |
277 | you have these freedoms and that you cannot take these freedoms away | |
278 | from anyone else. | |
279 | ||
6d2ebf8b | 280 | @node Contributors |
96a2c332 SS |
281 | @unnumberedsec Contributors to @value{GDBN} |
282 | ||
283 | Richard Stallman was the original author of @value{GDBN}, and of many | |
284 | other @sc{gnu} programs. Many others have contributed to its | |
285 | development. This section attempts to credit major contributors. One | |
286 | of the virtues of free software is that everyone is free to contribute | |
287 | to it; with regret, we cannot actually acknowledge everyone here. The | |
288 | file @file{ChangeLog} in the @value{GDBN} distribution approximates a | |
c906108c SS |
289 | blow-by-blow account. |
290 | ||
291 | Changes much prior to version 2.0 are lost in the mists of time. | |
292 | ||
293 | @quotation | |
294 | @emph{Plea:} Additions to this section are particularly welcome. If you | |
295 | or your friends (or enemies, to be evenhanded) have been unfairly | |
296 | omitted from this list, we would like to add your names! | |
297 | @end quotation | |
298 | ||
299 | So that they may not regard their many labors as thankless, we | |
300 | particularly thank those who shepherded @value{GDBN} through major | |
301 | releases: | |
8c70017b | 302 | Andrew Cagney (release 5.0); |
c906108c SS |
303 | Jim Blandy (release 4.18); |
304 | Jason Molenda (release 4.17); | |
305 | Stan Shebs (release 4.14); | |
306 | Fred Fish (releases 4.16, 4.15, 4.13, 4.12, 4.11, 4.10, and 4.9); | |
307 | Stu Grossman and John Gilmore (releases 4.8, 4.7, 4.6, 4.5, and 4.4); | |
308 | John Gilmore (releases 4.3, 4.2, 4.1, 4.0, and 3.9); | |
309 | Jim Kingdon (releases 3.5, 3.4, and 3.3); | |
310 | and Randy Smith (releases 3.2, 3.1, and 3.0). | |
311 | ||
312 | Richard Stallman, assisted at various times by Peter TerMaat, Chris | |
313 | Hanson, and Richard Mlynarik, handled releases through 2.8. | |
314 | ||
96a2c332 SS |
315 | Michael Tiemann is the author of most of the @sc{gnu} C++ support in |
316 | @value{GDBN}, with significant additional contributions from Per | |
317 | Bothner. James Clark wrote the @sc{gnu} C++ demangler. Early work on | |
318 | C++ was by Peter TerMaat (who also did much general update work leading | |
319 | to release 3.0). | |
c906108c SS |
320 | |
321 | @value{GDBN} 4 uses the BFD subroutine library to examine multiple | |
322 | object-file formats; BFD was a joint project of David V. | |
323 | Henkel-Wallace, Rich Pixley, Steve Chamberlain, and John Gilmore. | |
324 | ||
325 | David Johnson wrote the original COFF support; Pace Willison did | |
326 | the original support for encapsulated COFF. | |
327 | ||
96c405b3 | 328 | Brent Benson of Harris Computer Systems contributed DWARF2 support. |
c906108c SS |
329 | |
330 | Adam de Boor and Bradley Davis contributed the ISI Optimum V support. | |
331 | Per Bothner, Noboyuki Hikichi, and Alessandro Forin contributed MIPS | |
332 | support. | |
333 | Jean-Daniel Fekete contributed Sun 386i support. | |
334 | Chris Hanson improved the HP9000 support. | |
335 | Noboyuki Hikichi and Tomoyuki Hasei contributed Sony/News OS 3 support. | |
336 | David Johnson contributed Encore Umax support. | |
337 | Jyrki Kuoppala contributed Altos 3068 support. | |
338 | Jeff Law contributed HP PA and SOM support. | |
339 | Keith Packard contributed NS32K support. | |
340 | Doug Rabson contributed Acorn Risc Machine support. | |
341 | Bob Rusk contributed Harris Nighthawk CX-UX support. | |
342 | Chris Smith contributed Convex support (and Fortran debugging). | |
343 | Jonathan Stone contributed Pyramid support. | |
344 | Michael Tiemann contributed SPARC support. | |
345 | Tim Tucker contributed support for the Gould NP1 and Gould Powernode. | |
346 | Pace Willison contributed Intel 386 support. | |
347 | Jay Vosburgh contributed Symmetry support. | |
348 | ||
349 | Andreas Schwab contributed M68K Linux support. | |
350 | ||
351 | Rich Schaefer and Peter Schauer helped with support of SunOS shared | |
352 | libraries. | |
353 | ||
354 | Jay Fenlason and Roland McGrath ensured that @value{GDBN} and GAS agree | |
355 | about several machine instruction sets. | |
356 | ||
357 | Patrick Duval, Ted Goldstein, Vikram Koka and Glenn Engel helped develop | |
358 | remote debugging. Intel Corporation, Wind River Systems, AMD, and ARM | |
359 | contributed remote debugging modules for the i960, VxWorks, A29K UDI, | |
360 | and RDI targets, respectively. | |
361 | ||
362 | Brian Fox is the author of the readline libraries providing | |
363 | command-line editing and command history. | |
364 | ||
7a292a7a SS |
365 | Andrew Beers of SUNY Buffalo wrote the language-switching code, the |
366 | Modula-2 support, and contributed the Languages chapter of this manual. | |
c906108c | 367 | |
5d161b24 | 368 | Fred Fish wrote most of the support for Unix System Vr4. |
c906108c SS |
369 | He also enhanced the command-completion support to cover C++ overloaded |
370 | symbols. | |
c906108c SS |
371 | |
372 | Hitachi America, Ltd. sponsored the support for H8/300, H8/500, and | |
373 | Super-H processors. | |
374 | ||
375 | NEC sponsored the support for the v850, Vr4xxx, and Vr5xxx processors. | |
376 | ||
377 | Mitsubishi sponsored the support for D10V, D30V, and M32R/D processors. | |
378 | ||
379 | Toshiba sponsored the support for the TX39 Mips processor. | |
380 | ||
381 | Matsushita sponsored the support for the MN10200 and MN10300 processors. | |
382 | ||
96a2c332 | 383 | Fujitsu sponsored the support for SPARClite and FR30 processors. |
c906108c SS |
384 | |
385 | Kung Hsu, Jeff Law, and Rick Sladkey added support for hardware | |
386 | watchpoints. | |
387 | ||
388 | Michael Snyder added support for tracepoints. | |
389 | ||
390 | Stu Grossman wrote gdbserver. | |
391 | ||
392 | Jim Kingdon, Peter Schauer, Ian Taylor, and Stu Grossman made | |
96a2c332 | 393 | nearly innumerable bug fixes and cleanups throughout @value{GDBN}. |
c906108c SS |
394 | |
395 | The following people at the Hewlett-Packard Company contributed | |
396 | support for the PA-RISC 2.0 architecture, HP-UX 10.20, 10.30, and 11.0 | |
397 | (narrow mode), HP's implementation of kernel threads, HP's aC++ | |
398 | compiler, and the terminal user interface: Ben Krepp, Richard Title, | |
399 | John Bishop, Susan Macchia, Kathy Mann, Satish Pai, India Paul, Steve | |
400 | Rehrauer, and Elena Zannoni. Kim Haase provided HP-specific | |
401 | information in this manual. | |
402 | ||
96a2c332 SS |
403 | Cygnus Solutions has sponsored @value{GDBN} maintenance and much of its |
404 | development since 1991. Cygnus engineers who have worked on @value{GDBN} | |
2df3850c JM |
405 | fulltime include Mark Alexander, Jim Blandy, Per Bothner, Kevin |
406 | Buettner, Edith Epstein, Chris Faylor, Fred Fish, Martin Hunt, Jim | |
407 | Ingham, John Gilmore, Stu Grossman, Kung Hsu, Jim Kingdon, John Metzler, | |
408 | Fernando Nasser, Geoffrey Noer, Dawn Perchik, Rich Pixley, Zdenek | |
409 | Radouch, Keith Seitz, Stan Shebs, David Taylor, and Elena Zannoni. In | |
410 | addition, Dave Brolley, Ian Carmichael, Steve Chamberlain, Nick Clifton, | |
411 | JT Conklin, Stan Cox, DJ Delorie, Ulrich Drepper, Frank Eigler, Doug | |
412 | Evans, Sean Fagan, David Henkel-Wallace, Richard Henderson, Jeff | |
413 | Holcomb, Jeff Law, Jim Lemke, Tom Lord, Bob Manson, Michael Meissner, | |
414 | Jason Merrill, Catherine Moore, Drew Moseley, Ken Raeburn, Gavin | |
415 | Romig-Koch, Rob Savoye, Jamie Smith, Mike Stump, Ian Taylor, Angela | |
416 | Thomas, Michael Tiemann, Tom Tromey, Ron Unrau, Jim Wilson, and David | |
417 | Zuhn have made contributions both large and small. | |
c906108c SS |
418 | |
419 | ||
6d2ebf8b | 420 | @node Sample Session |
c906108c SS |
421 | @chapter A Sample @value{GDBN} Session |
422 | ||
423 | You can use this manual at your leisure to read all about @value{GDBN}. | |
424 | However, a handful of commands are enough to get started using the | |
425 | debugger. This chapter illustrates those commands. | |
426 | ||
427 | @iftex | |
428 | In this sample session, we emphasize user input like this: @b{input}, | |
429 | to make it easier to pick out from the surrounding output. | |
430 | @end iftex | |
431 | ||
432 | @c FIXME: this example may not be appropriate for some configs, where | |
433 | @c FIXME...primary interest is in remote use. | |
434 | ||
435 | One of the preliminary versions of @sc{gnu} @code{m4} (a generic macro | |
436 | processor) exhibits the following bug: sometimes, when we change its | |
437 | quote strings from the default, the commands used to capture one macro | |
438 | definition within another stop working. In the following short @code{m4} | |
439 | session, we define a macro @code{foo} which expands to @code{0000}; we | |
440 | then use the @code{m4} built-in @code{defn} to define @code{bar} as the | |
441 | same thing. However, when we change the open quote string to | |
442 | @code{<QUOTE>} and the close quote string to @code{<UNQUOTE>}, the same | |
443 | procedure fails to define a new synonym @code{baz}: | |
444 | ||
445 | @smallexample | |
446 | $ @b{cd gnu/m4} | |
447 | $ @b{./m4} | |
448 | @b{define(foo,0000)} | |
449 | ||
450 | @b{foo} | |
451 | 0000 | |
452 | @b{define(bar,defn(`foo'))} | |
453 | ||
454 | @b{bar} | |
455 | 0000 | |
456 | @b{changequote(<QUOTE>,<UNQUOTE>)} | |
457 | ||
458 | @b{define(baz,defn(<QUOTE>foo<UNQUOTE>))} | |
459 | @b{baz} | |
460 | @b{C-d} | |
461 | m4: End of input: 0: fatal error: EOF in string | |
462 | @end smallexample | |
463 | ||
464 | @noindent | |
465 | Let us use @value{GDBN} to try to see what is going on. | |
466 | ||
c906108c SS |
467 | @smallexample |
468 | $ @b{@value{GDBP} m4} | |
469 | @c FIXME: this falsifies the exact text played out, to permit smallbook | |
470 | @c FIXME... format to come out better. | |
471 | @value{GDBN} is free software and you are welcome to distribute copies | |
5d161b24 | 472 | of it under certain conditions; type "show copying" to see |
c906108c | 473 | the conditions. |
5d161b24 | 474 | There is absolutely no warranty for @value{GDBN}; type "show warranty" |
c906108c SS |
475 | for details. |
476 | ||
477 | @value{GDBN} @value{GDBVN}, Copyright 1999 Free Software Foundation, Inc... | |
478 | (@value{GDBP}) | |
479 | @end smallexample | |
c906108c SS |
480 | |
481 | @noindent | |
482 | @value{GDBN} reads only enough symbol data to know where to find the | |
483 | rest when needed; as a result, the first prompt comes up very quickly. | |
484 | We now tell @value{GDBN} to use a narrower display width than usual, so | |
485 | that examples fit in this manual. | |
486 | ||
487 | @smallexample | |
488 | (@value{GDBP}) @b{set width 70} | |
489 | @end smallexample | |
490 | ||
491 | @noindent | |
492 | We need to see how the @code{m4} built-in @code{changequote} works. | |
493 | Having looked at the source, we know the relevant subroutine is | |
494 | @code{m4_changequote}, so we set a breakpoint there with the @value{GDBN} | |
495 | @code{break} command. | |
496 | ||
497 | @smallexample | |
498 | (@value{GDBP}) @b{break m4_changequote} | |
499 | Breakpoint 1 at 0x62f4: file builtin.c, line 879. | |
500 | @end smallexample | |
501 | ||
502 | @noindent | |
503 | Using the @code{run} command, we start @code{m4} running under @value{GDBN} | |
504 | control; as long as control does not reach the @code{m4_changequote} | |
505 | subroutine, the program runs as usual: | |
506 | ||
507 | @smallexample | |
508 | (@value{GDBP}) @b{run} | |
509 | Starting program: /work/Editorial/gdb/gnu/m4/m4 | |
510 | @b{define(foo,0000)} | |
511 | ||
512 | @b{foo} | |
513 | 0000 | |
514 | @end smallexample | |
515 | ||
516 | @noindent | |
517 | To trigger the breakpoint, we call @code{changequote}. @value{GDBN} | |
518 | suspends execution of @code{m4}, displaying information about the | |
519 | context where it stops. | |
520 | ||
521 | @smallexample | |
522 | @b{changequote(<QUOTE>,<UNQUOTE>)} | |
523 | ||
5d161b24 | 524 | Breakpoint 1, m4_changequote (argc=3, argv=0x33c70) |
c906108c SS |
525 | at builtin.c:879 |
526 | 879 if (bad_argc(TOKEN_DATA_TEXT(argv[0]),argc,1,3)) | |
527 | @end smallexample | |
528 | ||
529 | @noindent | |
530 | Now we use the command @code{n} (@code{next}) to advance execution to | |
531 | the next line of the current function. | |
532 | ||
533 | @smallexample | |
534 | (@value{GDBP}) @b{n} | |
535 | 882 set_quotes((argc >= 2) ? TOKEN_DATA_TEXT(argv[1])\ | |
536 | : nil, | |
537 | @end smallexample | |
538 | ||
539 | @noindent | |
540 | @code{set_quotes} looks like a promising subroutine. We can go into it | |
541 | by using the command @code{s} (@code{step}) instead of @code{next}. | |
542 | @code{step} goes to the next line to be executed in @emph{any} | |
543 | subroutine, so it steps into @code{set_quotes}. | |
544 | ||
545 | @smallexample | |
546 | (@value{GDBP}) @b{s} | |
547 | set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>") | |
548 | at input.c:530 | |
549 | 530 if (lquote != def_lquote) | |
550 | @end smallexample | |
551 | ||
552 | @noindent | |
553 | The display that shows the subroutine where @code{m4} is now | |
554 | suspended (and its arguments) is called a stack frame display. It | |
555 | shows a summary of the stack. We can use the @code{backtrace} | |
556 | command (which can also be spelled @code{bt}), to see where we are | |
557 | in the stack as a whole: the @code{backtrace} command displays a | |
558 | stack frame for each active subroutine. | |
559 | ||
560 | @smallexample | |
561 | (@value{GDBP}) @b{bt} | |
562 | #0 set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>") | |
563 | at input.c:530 | |
5d161b24 | 564 | #1 0x6344 in m4_changequote (argc=3, argv=0x33c70) |
c906108c SS |
565 | at builtin.c:882 |
566 | #2 0x8174 in expand_macro (sym=0x33320) at macro.c:242 | |
567 | #3 0x7a88 in expand_token (obs=0x0, t=209696, td=0xf7fffa30) | |
568 | at macro.c:71 | |
569 | #4 0x79dc in expand_input () at macro.c:40 | |
570 | #5 0x2930 in main (argc=0, argv=0xf7fffb20) at m4.c:195 | |
571 | @end smallexample | |
572 | ||
573 | @noindent | |
574 | We step through a few more lines to see what happens. The first two | |
575 | times, we can use @samp{s}; the next two times we use @code{n} to avoid | |
576 | falling into the @code{xstrdup} subroutine. | |
577 | ||
578 | @smallexample | |
579 | (@value{GDBP}) @b{s} | |
580 | 0x3b5c 532 if (rquote != def_rquote) | |
581 | (@value{GDBP}) @b{s} | |
582 | 0x3b80 535 lquote = (lq == nil || *lq == '\0') ? \ | |
583 | def_lquote : xstrdup(lq); | |
584 | (@value{GDBP}) @b{n} | |
585 | 536 rquote = (rq == nil || *rq == '\0') ? def_rquote\ | |
586 | : xstrdup(rq); | |
587 | (@value{GDBP}) @b{n} | |
588 | 538 len_lquote = strlen(rquote); | |
589 | @end smallexample | |
590 | ||
591 | @noindent | |
592 | The last line displayed looks a little odd; we can examine the variables | |
593 | @code{lquote} and @code{rquote} to see if they are in fact the new left | |
594 | and right quotes we specified. We use the command @code{p} | |
595 | (@code{print}) to see their values. | |
596 | ||
597 | @smallexample | |
598 | (@value{GDBP}) @b{p lquote} | |
599 | $1 = 0x35d40 "<QUOTE>" | |
600 | (@value{GDBP}) @b{p rquote} | |
601 | $2 = 0x35d50 "<UNQUOTE>" | |
602 | @end smallexample | |
603 | ||
604 | @noindent | |
605 | @code{lquote} and @code{rquote} are indeed the new left and right quotes. | |
606 | To look at some context, we can display ten lines of source | |
607 | surrounding the current line with the @code{l} (@code{list}) command. | |
608 | ||
609 | @smallexample | |
610 | (@value{GDBP}) @b{l} | |
611 | 533 xfree(rquote); | |
612 | 534 | |
613 | 535 lquote = (lq == nil || *lq == '\0') ? def_lquote\ | |
614 | : xstrdup (lq); | |
615 | 536 rquote = (rq == nil || *rq == '\0') ? def_rquote\ | |
616 | : xstrdup (rq); | |
617 | 537 | |
618 | 538 len_lquote = strlen(rquote); | |
619 | 539 len_rquote = strlen(lquote); | |
620 | 540 @} | |
621 | 541 | |
622 | 542 void | |
623 | @end smallexample | |
624 | ||
625 | @noindent | |
626 | Let us step past the two lines that set @code{len_lquote} and | |
627 | @code{len_rquote}, and then examine the values of those variables. | |
628 | ||
629 | @smallexample | |
630 | (@value{GDBP}) @b{n} | |
631 | 539 len_rquote = strlen(lquote); | |
632 | (@value{GDBP}) @b{n} | |
633 | 540 @} | |
634 | (@value{GDBP}) @b{p len_lquote} | |
635 | $3 = 9 | |
636 | (@value{GDBP}) @b{p len_rquote} | |
637 | $4 = 7 | |
638 | @end smallexample | |
639 | ||
640 | @noindent | |
641 | That certainly looks wrong, assuming @code{len_lquote} and | |
642 | @code{len_rquote} are meant to be the lengths of @code{lquote} and | |
643 | @code{rquote} respectively. We can set them to better values using | |
644 | the @code{p} command, since it can print the value of | |
645 | any expression---and that expression can include subroutine calls and | |
646 | assignments. | |
647 | ||
648 | @smallexample | |
649 | (@value{GDBP}) @b{p len_lquote=strlen(lquote)} | |
650 | $5 = 7 | |
651 | (@value{GDBP}) @b{p len_rquote=strlen(rquote)} | |
652 | $6 = 9 | |
653 | @end smallexample | |
654 | ||
655 | @noindent | |
656 | Is that enough to fix the problem of using the new quotes with the | |
657 | @code{m4} built-in @code{defn}? We can allow @code{m4} to continue | |
658 | executing with the @code{c} (@code{continue}) command, and then try the | |
659 | example that caused trouble initially: | |
660 | ||
661 | @smallexample | |
662 | (@value{GDBP}) @b{c} | |
663 | Continuing. | |
664 | ||
665 | @b{define(baz,defn(<QUOTE>foo<UNQUOTE>))} | |
666 | ||
667 | baz | |
668 | 0000 | |
669 | @end smallexample | |
670 | ||
671 | @noindent | |
672 | Success! The new quotes now work just as well as the default ones. The | |
673 | problem seems to have been just the two typos defining the wrong | |
674 | lengths. We allow @code{m4} exit by giving it an EOF as input: | |
675 | ||
676 | @smallexample | |
677 | @b{C-d} | |
678 | Program exited normally. | |
679 | @end smallexample | |
680 | ||
681 | @noindent | |
682 | The message @samp{Program exited normally.} is from @value{GDBN}; it | |
683 | indicates @code{m4} has finished executing. We can end our @value{GDBN} | |
684 | session with the @value{GDBN} @code{quit} command. | |
685 | ||
686 | @smallexample | |
687 | (@value{GDBP}) @b{quit} | |
688 | @end smallexample | |
c906108c | 689 | |
6d2ebf8b | 690 | @node Invocation |
c906108c SS |
691 | @chapter Getting In and Out of @value{GDBN} |
692 | ||
693 | This chapter discusses how to start @value{GDBN}, and how to get out of it. | |
5d161b24 | 694 | The essentials are: |
c906108c | 695 | @itemize @bullet |
5d161b24 | 696 | @item |
53a5351d | 697 | type @samp{@value{GDBP}} to start @value{GDBN}. |
5d161b24 | 698 | @item |
c906108c SS |
699 | type @kbd{quit} or @kbd{C-d} to exit. |
700 | @end itemize | |
701 | ||
702 | @menu | |
703 | * Invoking GDB:: How to start @value{GDBN} | |
704 | * Quitting GDB:: How to quit @value{GDBN} | |
705 | * Shell Commands:: How to use shell commands inside @value{GDBN} | |
706 | @end menu | |
707 | ||
6d2ebf8b | 708 | @node Invoking GDB |
c906108c SS |
709 | @section Invoking @value{GDBN} |
710 | ||
c906108c SS |
711 | Invoke @value{GDBN} by running the program @code{@value{GDBP}}. Once started, |
712 | @value{GDBN} reads commands from the terminal until you tell it to exit. | |
713 | ||
714 | You can also run @code{@value{GDBP}} with a variety of arguments and options, | |
715 | to specify more of your debugging environment at the outset. | |
716 | ||
c906108c SS |
717 | The command-line options described here are designed |
718 | to cover a variety of situations; in some environments, some of these | |
5d161b24 | 719 | options may effectively be unavailable. |
c906108c SS |
720 | |
721 | The most usual way to start @value{GDBN} is with one argument, | |
722 | specifying an executable program: | |
723 | ||
724 | @example | |
725 | @value{GDBP} @var{program} | |
726 | @end example | |
727 | ||
c906108c SS |
728 | @noindent |
729 | You can also start with both an executable program and a core file | |
730 | specified: | |
731 | ||
732 | @example | |
733 | @value{GDBP} @var{program} @var{core} | |
734 | @end example | |
735 | ||
736 | You can, instead, specify a process ID as a second argument, if you want | |
737 | to debug a running process: | |
738 | ||
739 | @example | |
740 | @value{GDBP} @var{program} 1234 | |
741 | @end example | |
742 | ||
743 | @noindent | |
744 | would attach @value{GDBN} to process @code{1234} (unless you also have a file | |
745 | named @file{1234}; @value{GDBN} does check for a core file first). | |
746 | ||
c906108c | 747 | Taking advantage of the second command-line argument requires a fairly |
2df3850c JM |
748 | complete operating system; when you use @value{GDBN} as a remote |
749 | debugger attached to a bare board, there may not be any notion of | |
750 | ``process'', and there is often no way to get a core dump. @value{GDBN} | |
751 | will warn you if it is unable to attach or to read core dumps. | |
c906108c | 752 | |
96a2c332 | 753 | You can run @code{@value{GDBP}} without printing the front material, which describes |
c906108c SS |
754 | @value{GDBN}'s non-warranty, by specifying @code{-silent}: |
755 | ||
756 | @smallexample | |
757 | @value{GDBP} -silent | |
758 | @end smallexample | |
759 | ||
760 | @noindent | |
761 | You can further control how @value{GDBN} starts up by using command-line | |
762 | options. @value{GDBN} itself can remind you of the options available. | |
763 | ||
764 | @noindent | |
765 | Type | |
766 | ||
767 | @example | |
768 | @value{GDBP} -help | |
769 | @end example | |
770 | ||
771 | @noindent | |
772 | to display all available options and briefly describe their use | |
773 | (@samp{@value{GDBP} -h} is a shorter equivalent). | |
774 | ||
775 | All options and command line arguments you give are processed | |
776 | in sequential order. The order makes a difference when the | |
777 | @samp{-x} option is used. | |
778 | ||
779 | ||
780 | @menu | |
c906108c SS |
781 | * File Options:: Choosing files |
782 | * Mode Options:: Choosing modes | |
783 | @end menu | |
784 | ||
6d2ebf8b | 785 | @node File Options |
c906108c SS |
786 | @subsection Choosing files |
787 | ||
2df3850c | 788 | When @value{GDBN} starts, it reads any arguments other than options as |
c906108c SS |
789 | specifying an executable file and core file (or process ID). This is |
790 | the same as if the arguments were specified by the @samp{-se} and | |
791 | @samp{-c} options respectively. (@value{GDBN} reads the first argument | |
792 | that does not have an associated option flag as equivalent to the | |
793 | @samp{-se} option followed by that argument; and the second argument | |
794 | that does not have an associated option flag, if any, as equivalent to | |
795 | the @samp{-c} option followed by that argument.) | |
7a292a7a SS |
796 | |
797 | If @value{GDBN} has not been configured to included core file support, | |
798 | such as for most embedded targets, then it will complain about a second | |
799 | argument and ignore it. | |
c906108c SS |
800 | |
801 | Many options have both long and short forms; both are shown in the | |
802 | following list. @value{GDBN} also recognizes the long forms if you truncate | |
803 | them, so long as enough of the option is present to be unambiguous. | |
804 | (If you prefer, you can flag option arguments with @samp{--} rather | |
805 | than @samp{-}, though we illustrate the more usual convention.) | |
806 | ||
d700128c EZ |
807 | @c NOTE: the @cindex entries here use double dashes ON PURPOSE. This |
808 | @c way, both those who look for -foo and --foo in the index, will find | |
809 | @c it. | |
810 | ||
c906108c SS |
811 | @table @code |
812 | @item -symbols @var{file} | |
813 | @itemx -s @var{file} | |
d700128c EZ |
814 | @cindex @code{--symbols} |
815 | @cindex @code{-s} | |
c906108c SS |
816 | Read symbol table from file @var{file}. |
817 | ||
818 | @item -exec @var{file} | |
819 | @itemx -e @var{file} | |
d700128c EZ |
820 | @cindex @code{--exec} |
821 | @cindex @code{-e} | |
7a292a7a SS |
822 | Use file @var{file} as the executable file to execute when appropriate, |
823 | and for examining pure data in conjunction with a core dump. | |
c906108c SS |
824 | |
825 | @item -se @var{file} | |
d700128c | 826 | @cindex @code{--se} |
c906108c SS |
827 | Read symbol table from file @var{file} and use it as the executable |
828 | file. | |
829 | ||
c906108c SS |
830 | @item -core @var{file} |
831 | @itemx -c @var{file} | |
d700128c EZ |
832 | @cindex @code{--core} |
833 | @cindex @code{-c} | |
c906108c SS |
834 | Use file @var{file} as a core dump to examine. |
835 | ||
836 | @item -c @var{number} | |
837 | Connect to process ID @var{number}, as with the @code{attach} command | |
838 | (unless there is a file in core-dump format named @var{number}, in which | |
839 | case @samp{-c} specifies that file as a core dump to read). | |
c906108c SS |
840 | |
841 | @item -command @var{file} | |
842 | @itemx -x @var{file} | |
d700128c EZ |
843 | @cindex @code{--command} |
844 | @cindex @code{-x} | |
c906108c SS |
845 | Execute @value{GDBN} commands from file @var{file}. @xref{Command |
846 | Files,, Command files}. | |
847 | ||
848 | @item -directory @var{directory} | |
849 | @itemx -d @var{directory} | |
d700128c EZ |
850 | @cindex @code{--directory} |
851 | @cindex @code{-d} | |
c906108c SS |
852 | Add @var{directory} to the path to search for source files. |
853 | ||
c906108c SS |
854 | @item -m |
855 | @itemx -mapped | |
d700128c EZ |
856 | @cindex @code{--mapped} |
857 | @cindex @code{-m} | |
c906108c SS |
858 | @emph{Warning: this option depends on operating system facilities that are not |
859 | supported on all systems.}@* | |
860 | If memory-mapped files are available on your system through the @code{mmap} | |
5d161b24 | 861 | system call, you can use this option |
c906108c SS |
862 | to have @value{GDBN} write the symbols from your |
863 | program into a reusable file in the current directory. If the program you are debugging is | |
96a2c332 | 864 | called @file{/tmp/fred}, the mapped symbol file is @file{/tmp/fred.syms}. |
c906108c SS |
865 | Future @value{GDBN} debugging sessions notice the presence of this file, |
866 | and can quickly map in symbol information from it, rather than reading | |
867 | the symbol table from the executable program. | |
868 | ||
869 | The @file{.syms} file is specific to the host machine where @value{GDBN} | |
870 | is run. It holds an exact image of the internal @value{GDBN} symbol | |
871 | table. It cannot be shared across multiple host platforms. | |
c906108c | 872 | |
c906108c SS |
873 | @item -r |
874 | @itemx -readnow | |
d700128c EZ |
875 | @cindex @code{--readnow} |
876 | @cindex @code{-r} | |
c906108c SS |
877 | Read each symbol file's entire symbol table immediately, rather than |
878 | the default, which is to read it incrementally as it is needed. | |
879 | This makes startup slower, but makes future operations faster. | |
53a5351d | 880 | |
c906108c SS |
881 | @end table |
882 | ||
2df3850c | 883 | You typically combine the @code{-mapped} and @code{-readnow} options in |
c906108c | 884 | order to build a @file{.syms} file that contains complete symbol |
2df3850c JM |
885 | information. (@xref{Files,,Commands to specify files}, for information |
886 | on @file{.syms} files.) A simple @value{GDBN} invocation to do nothing | |
887 | but build a @file{.syms} file for future use is: | |
c906108c SS |
888 | |
889 | @example | |
2df3850c | 890 | gdb -batch -nx -mapped -readnow programname |
c906108c | 891 | @end example |
c906108c | 892 | |
6d2ebf8b | 893 | @node Mode Options |
c906108c SS |
894 | @subsection Choosing modes |
895 | ||
896 | You can run @value{GDBN} in various alternative modes---for example, in | |
897 | batch mode or quiet mode. | |
898 | ||
899 | @table @code | |
900 | @item -nx | |
901 | @itemx -n | |
d700128c EZ |
902 | @cindex @code{--nx} |
903 | @cindex @code{-n} | |
2df3850c JM |
904 | Do not execute commands found in any initialization files (normally |
905 | called @file{.gdbinit}, or @file{gdb.ini} on PCs). Normally, | |
906 | @value{GDBN} executes the commands in these files after all the command | |
907 | options and arguments have been processed. @xref{Command Files,,Command | |
908 | files}. | |
c906108c SS |
909 | |
910 | @item -quiet | |
d700128c | 911 | @itemx -silent |
c906108c | 912 | @itemx -q |
d700128c EZ |
913 | @cindex @code{--quiet} |
914 | @cindex @code{--silent} | |
915 | @cindex @code{-q} | |
c906108c SS |
916 | ``Quiet''. Do not print the introductory and copyright messages. These |
917 | messages are also suppressed in batch mode. | |
918 | ||
919 | @item -batch | |
d700128c | 920 | @cindex @code{--batch} |
c906108c SS |
921 | Run in batch mode. Exit with status @code{0} after processing all the |
922 | command files specified with @samp{-x} (and all commands from | |
923 | initialization files, if not inhibited with @samp{-n}). Exit with | |
924 | nonzero status if an error occurs in executing the @value{GDBN} commands | |
925 | in the command files. | |
926 | ||
2df3850c JM |
927 | Batch mode may be useful for running @value{GDBN} as a filter, for |
928 | example to download and run a program on another computer; in order to | |
929 | make this more useful, the message | |
c906108c SS |
930 | |
931 | @example | |
932 | Program exited normally. | |
933 | @end example | |
934 | ||
935 | @noindent | |
2df3850c JM |
936 | (which is ordinarily issued whenever a program running under |
937 | @value{GDBN} control terminates) is not issued when running in batch | |
938 | mode. | |
939 | ||
940 | @item -nowindows | |
941 | @itemx -nw | |
d700128c EZ |
942 | @cindex @code{--nowindows} |
943 | @cindex @code{-nw} | |
2df3850c | 944 | ``No windows''. If @value{GDBN} comes with a graphical user interface |
96a2c332 | 945 | (GUI) built in, then this option tells @value{GDBN} to only use the command-line |
2df3850c JM |
946 | interface. If no GUI is available, this option has no effect. |
947 | ||
948 | @item -windows | |
949 | @itemx -w | |
d700128c EZ |
950 | @cindex @code{--windows} |
951 | @cindex @code{-w} | |
2df3850c JM |
952 | If @value{GDBN} includes a GUI, then this option requires it to be |
953 | used if possible. | |
c906108c SS |
954 | |
955 | @item -cd @var{directory} | |
d700128c | 956 | @cindex @code{--cd} |
c906108c SS |
957 | Run @value{GDBN} using @var{directory} as its working directory, |
958 | instead of the current directory. | |
959 | ||
c906108c SS |
960 | @item -fullname |
961 | @itemx -f | |
d700128c EZ |
962 | @cindex @code{--fullname} |
963 | @cindex @code{-f} | |
7a292a7a SS |
964 | @sc{gnu} Emacs sets this option when it runs @value{GDBN} as a |
965 | subprocess. It tells @value{GDBN} to output the full file name and line | |
966 | number in a standard, recognizable fashion each time a stack frame is | |
967 | displayed (which includes each time your program stops). This | |
968 | recognizable format looks like two @samp{\032} characters, followed by | |
969 | the file name, line number and character position separated by colons, | |
970 | and a newline. The Emacs-to-@value{GDBN} interface program uses the two | |
971 | @samp{\032} characters as a signal to display the source code for the | |
972 | frame. | |
c906108c | 973 | |
d700128c EZ |
974 | @item -epoch |
975 | @cindex @code{--epoch} | |
976 | The Epoch Emacs-@value{GDBN} interface sets this option when it runs | |
977 | @value{GDBN} as a subprocess. It tells @value{GDBN} to modify its print | |
978 | routines so as to allow Epoch to display values of expressions in a | |
979 | separate window. | |
980 | ||
981 | @item -annotate @var{level} | |
982 | @cindex @code{--annotate} | |
983 | This option sets the @dfn{annotation level} inside @value{GDBN}. Its | |
984 | effect is identical to using @samp{set annotate @var{level}} | |
985 | (@pxref{Annotations}). | |
986 | Annotation level controls how much information does @value{GDBN} print | |
987 | together with its prompt, values of expressions, source lines, and other | |
988 | types of output. Level 0 is the normal, level 1 is for use when | |
989 | @value{GDBN} is run as a subprocess of @sc{gnu} Emacs, level 2 is the | |
990 | maximum annotation suitable for programs that control @value{GDBN}. | |
991 | ||
992 | @item -async | |
993 | @cindex @code{--async} | |
994 | Use the asynchronous event loop for the command-line interface. | |
995 | @value{GDBN} processes all events, such as user keyboard input, via a | |
996 | special event loop. This allows @value{GDBN} to accept and process user | |
997 | commands in parallel with the debugged process being | |
998 | run@footnote{@value{GDBN} built with @sc{djgpp} tools for | |
999 | MS-DOS/MS-Windows supports this mode of operation, but the event loop is | |
1000 | suspended when the debuggee runs.}, so you don't need to wait for | |
1001 | control to return to @value{GDBN} before you type the next command. | |
1002 | (@emph{Note:} as of version 5.0, the target side of the asynchronous | |
1003 | operation is not yet in place, so @samp{-async} does not work fully | |
1004 | yet.) | |
1005 | @c FIXME: when the target side of the event loop is done, the above NOTE | |
1006 | @c should be removed. | |
1007 | ||
1008 | When the standard input is connected to a terminal device, @value{GDBN} | |
1009 | uses the asynchronous event loop by default, unless disabled by the | |
1010 | @samp{-noasync} option. | |
1011 | ||
1012 | @item -noasync | |
1013 | @cindex @code{--noasync} | |
1014 | Disable the asynchronous event loop for the command-line interface. | |
1015 | ||
2df3850c JM |
1016 | @item -baud @var{bps} |
1017 | @itemx -b @var{bps} | |
d700128c EZ |
1018 | @cindex @code{--baud} |
1019 | @cindex @code{-b} | |
c906108c SS |
1020 | Set the line speed (baud rate or bits per second) of any serial |
1021 | interface used by @value{GDBN} for remote debugging. | |
c906108c SS |
1022 | |
1023 | @item -tty @var{device} | |
d700128c EZ |
1024 | @itemx -t @var{device} |
1025 | @cindex @code{--tty} | |
1026 | @cindex @code{-t} | |
c906108c SS |
1027 | Run using @var{device} for your program's standard input and output. |
1028 | @c FIXME: kingdon thinks there is more to -tty. Investigate. | |
c906108c | 1029 | |
53a5351d JM |
1030 | @c resolve the situation of these eventually |
1031 | @c @item -tui | |
d700128c | 1032 | @c @cindex @code{--tui} |
53a5351d JM |
1033 | @c Use a Terminal User Interface. For information, use your Web browser to |
1034 | @c read the file @file{TUI.html}, which is usually installed in the | |
1035 | @c directory @code{/opt/langtools/wdb/doc} on HP-UX systems. Do not use | |
1036 | @c this option if you run @value{GDBN} from Emacs (see @pxref{Emacs, ,Using | |
1037 | @c @value{GDBN} under @sc{gnu} Emacs}). | |
1038 | ||
1039 | @c @item -xdb | |
d700128c | 1040 | @c @cindex @code{--xdb} |
53a5351d JM |
1041 | @c Run in XDB compatibility mode, allowing the use of certain XDB commands. |
1042 | @c For information, see the file @file{xdb_trans.html}, which is usually | |
1043 | @c installed in the directory @code{/opt/langtools/wdb/doc} on HP-UX | |
1044 | @c systems. | |
1045 | ||
d700128c EZ |
1046 | @item -interpreter @var{interp} |
1047 | @cindex @code{--interpreter} | |
1048 | Use the interpreter @var{interp} for interface with the controlling | |
1049 | program or device. This option is meant to be set by programs which | |
1050 | communicate with @value{GDBN} using it as a back end. For example, | |
1051 | @samp{--interpreter=mi} causes @value{GDBN} to use the @dfn{gdbmi | |
7162c0ca | 1052 | interface} (@pxref{GDB/MI, , The @sc{gdb/mi} Interface}). |
d700128c EZ |
1053 | |
1054 | @item -write | |
1055 | @cindex @code{--write} | |
1056 | Open the executable and core files for both reading and writing. This | |
1057 | is equivalent to the @samp{set write on} command inside @value{GDBN} | |
1058 | (@pxref{Patching}). | |
1059 | ||
1060 | @item -statistics | |
1061 | @cindex @code{--statistics} | |
1062 | This option causes @value{GDBN} to print statistics about time and | |
1063 | memory usage after it completes each command and returns to the prompt. | |
1064 | ||
1065 | @item -version | |
1066 | @cindex @code{--version} | |
1067 | This option causes @value{GDBN} to print its version number and | |
1068 | no-warranty blurb, and exit. | |
1069 | ||
c906108c SS |
1070 | @end table |
1071 | ||
6d2ebf8b | 1072 | @node Quitting GDB |
c906108c SS |
1073 | @section Quitting @value{GDBN} |
1074 | @cindex exiting @value{GDBN} | |
1075 | @cindex leaving @value{GDBN} | |
1076 | ||
1077 | @table @code | |
1078 | @kindex quit @r{[}@var{expression}@r{]} | |
41afff9a | 1079 | @kindex q @r{(@code{quit})} |
96a2c332 SS |
1080 | @item quit @r{[}@var{expression}@r{]} |
1081 | @itemx q | |
1082 | To exit @value{GDBN}, use the @code{quit} command (abbreviated | |
1083 | @code{q}), or type an end-of-file character (usually @kbd{C-d}). If you | |
1084 | do not supply @var{expression}, @value{GDBN} will terminate normally; | |
1085 | otherwise it will terminate using the result of @var{expression} as the | |
1086 | error code. | |
c906108c SS |
1087 | @end table |
1088 | ||
1089 | @cindex interrupt | |
1090 | An interrupt (often @kbd{C-c}) does not exit from @value{GDBN}, but rather | |
1091 | terminates the action of any @value{GDBN} command that is in progress and | |
1092 | returns to @value{GDBN} command level. It is safe to type the interrupt | |
1093 | character at any time because @value{GDBN} does not allow it to take effect | |
1094 | until a time when it is safe. | |
1095 | ||
c906108c SS |
1096 | If you have been using @value{GDBN} to control an attached process or |
1097 | device, you can release it with the @code{detach} command | |
1098 | (@pxref{Attach, ,Debugging an already-running process}). | |
c906108c | 1099 | |
6d2ebf8b | 1100 | @node Shell Commands |
c906108c SS |
1101 | @section Shell commands |
1102 | ||
1103 | If you need to execute occasional shell commands during your | |
1104 | debugging session, there is no need to leave or suspend @value{GDBN}; you can | |
1105 | just use the @code{shell} command. | |
1106 | ||
1107 | @table @code | |
1108 | @kindex shell | |
1109 | @cindex shell escape | |
1110 | @item shell @var{command string} | |
1111 | Invoke a standard shell to execute @var{command string}. | |
c906108c | 1112 | If it exists, the environment variable @code{SHELL} determines which |
d4f3574e SS |
1113 | shell to run. Otherwise @value{GDBN} uses the default shell |
1114 | (@file{/bin/sh} on Unix systems, @file{COMMAND.COM} on MS-DOS, etc.). | |
c906108c SS |
1115 | @end table |
1116 | ||
1117 | The utility @code{make} is often needed in development environments. | |
1118 | You do not have to use the @code{shell} command for this purpose in | |
1119 | @value{GDBN}: | |
1120 | ||
1121 | @table @code | |
1122 | @kindex make | |
1123 | @cindex calling make | |
1124 | @item make @var{make-args} | |
1125 | Execute the @code{make} program with the specified | |
1126 | arguments. This is equivalent to @samp{shell make @var{make-args}}. | |
1127 | @end table | |
1128 | ||
6d2ebf8b | 1129 | @node Commands |
c906108c SS |
1130 | @chapter @value{GDBN} Commands |
1131 | ||
1132 | You can abbreviate a @value{GDBN} command to the first few letters of the command | |
1133 | name, if that abbreviation is unambiguous; and you can repeat certain | |
1134 | @value{GDBN} commands by typing just @key{RET}. You can also use the @key{TAB} | |
1135 | key to get @value{GDBN} to fill out the rest of a word in a command (or to | |
1136 | show you the alternatives available, if there is more than one possibility). | |
1137 | ||
1138 | @menu | |
1139 | * Command Syntax:: How to give commands to @value{GDBN} | |
1140 | * Completion:: Command completion | |
1141 | * Help:: How to ask @value{GDBN} for help | |
1142 | @end menu | |
1143 | ||
6d2ebf8b | 1144 | @node Command Syntax |
c906108c SS |
1145 | @section Command syntax |
1146 | ||
1147 | A @value{GDBN} command is a single line of input. There is no limit on | |
1148 | how long it can be. It starts with a command name, which is followed by | |
1149 | arguments whose meaning depends on the command name. For example, the | |
1150 | command @code{step} accepts an argument which is the number of times to | |
1151 | step, as in @samp{step 5}. You can also use the @code{step} command | |
96a2c332 | 1152 | with no arguments. Some commands do not allow any arguments. |
c906108c SS |
1153 | |
1154 | @cindex abbreviation | |
1155 | @value{GDBN} command names may always be truncated if that abbreviation is | |
1156 | unambiguous. Other possible command abbreviations are listed in the | |
1157 | documentation for individual commands. In some cases, even ambiguous | |
1158 | abbreviations are allowed; for example, @code{s} is specially defined as | |
1159 | equivalent to @code{step} even though there are other commands whose | |
1160 | names start with @code{s}. You can test abbreviations by using them as | |
1161 | arguments to the @code{help} command. | |
1162 | ||
1163 | @cindex repeating commands | |
41afff9a | 1164 | @kindex RET @r{(repeat last command)} |
c906108c | 1165 | A blank line as input to @value{GDBN} (typing just @key{RET}) means to |
96a2c332 | 1166 | repeat the previous command. Certain commands (for example, @code{run}) |
c906108c SS |
1167 | will not repeat this way; these are commands whose unintentional |
1168 | repetition might cause trouble and which you are unlikely to want to | |
1169 | repeat. | |
1170 | ||
1171 | The @code{list} and @code{x} commands, when you repeat them with | |
1172 | @key{RET}, construct new arguments rather than repeating | |
1173 | exactly as typed. This permits easy scanning of source or memory. | |
1174 | ||
1175 | @value{GDBN} can also use @key{RET} in another way: to partition lengthy | |
1176 | output, in a way similar to the common utility @code{more} | |
1177 | (@pxref{Screen Size,,Screen size}). Since it is easy to press one | |
1178 | @key{RET} too many in this situation, @value{GDBN} disables command | |
1179 | repetition after any command that generates this sort of display. | |
1180 | ||
41afff9a | 1181 | @kindex # @r{(a comment)} |
c906108c SS |
1182 | @cindex comment |
1183 | Any text from a @kbd{#} to the end of the line is a comment; it does | |
1184 | nothing. This is useful mainly in command files (@pxref{Command | |
1185 | Files,,Command files}). | |
1186 | ||
6d2ebf8b | 1187 | @node Completion |
c906108c SS |
1188 | @section Command completion |
1189 | ||
1190 | @cindex completion | |
1191 | @cindex word completion | |
1192 | @value{GDBN} can fill in the rest of a word in a command for you, if there is | |
1193 | only one possibility; it can also show you what the valid possibilities | |
1194 | are for the next word in a command, at any time. This works for @value{GDBN} | |
1195 | commands, @value{GDBN} subcommands, and the names of symbols in your program. | |
1196 | ||
1197 | Press the @key{TAB} key whenever you want @value{GDBN} to fill out the rest | |
1198 | of a word. If there is only one possibility, @value{GDBN} fills in the | |
1199 | word, and waits for you to finish the command (or press @key{RET} to | |
1200 | enter it). For example, if you type | |
1201 | ||
1202 | @c FIXME "@key" does not distinguish its argument sufficiently to permit | |
1203 | @c complete accuracy in these examples; space introduced for clarity. | |
1204 | @c If texinfo enhancements make it unnecessary, it would be nice to | |
1205 | @c replace " @key" by "@key" in the following... | |
1206 | @example | |
1207 | (@value{GDBP}) info bre @key{TAB} | |
1208 | @end example | |
1209 | ||
1210 | @noindent | |
1211 | @value{GDBN} fills in the rest of the word @samp{breakpoints}, since that is | |
1212 | the only @code{info} subcommand beginning with @samp{bre}: | |
1213 | ||
1214 | @example | |
1215 | (@value{GDBP}) info breakpoints | |
1216 | @end example | |
1217 | ||
1218 | @noindent | |
1219 | You can either press @key{RET} at this point, to run the @code{info | |
1220 | breakpoints} command, or backspace and enter something else, if | |
1221 | @samp{breakpoints} does not look like the command you expected. (If you | |
1222 | were sure you wanted @code{info breakpoints} in the first place, you | |
1223 | might as well just type @key{RET} immediately after @samp{info bre}, | |
1224 | to exploit command abbreviations rather than command completion). | |
1225 | ||
1226 | If there is more than one possibility for the next word when you press | |
1227 | @key{TAB}, @value{GDBN} sounds a bell. You can either supply more | |
1228 | characters and try again, or just press @key{TAB} a second time; | |
1229 | @value{GDBN} displays all the possible completions for that word. For | |
1230 | example, you might want to set a breakpoint on a subroutine whose name | |
1231 | begins with @samp{make_}, but when you type @kbd{b make_@key{TAB}} @value{GDBN} | |
1232 | just sounds the bell. Typing @key{TAB} again displays all the | |
1233 | function names in your program that begin with those characters, for | |
1234 | example: | |
1235 | ||
1236 | @example | |
1237 | (@value{GDBP}) b make_ @key{TAB} | |
1238 | @exdent @value{GDBN} sounds bell; press @key{TAB} again, to see: | |
5d161b24 DB |
1239 | make_a_section_from_file make_environ |
1240 | make_abs_section make_function_type | |
1241 | make_blockvector make_pointer_type | |
1242 | make_cleanup make_reference_type | |
c906108c SS |
1243 | make_command make_symbol_completion_list |
1244 | (@value{GDBP}) b make_ | |
1245 | @end example | |
1246 | ||
1247 | @noindent | |
1248 | After displaying the available possibilities, @value{GDBN} copies your | |
1249 | partial input (@samp{b make_} in the example) so you can finish the | |
1250 | command. | |
1251 | ||
1252 | If you just want to see the list of alternatives in the first place, you | |
1253 | can press @kbd{M-?} rather than pressing @key{TAB} twice. @kbd{M-?} | |
7a292a7a | 1254 | means @kbd{@key{META} ?}. You can type this either by holding down a |
c906108c | 1255 | key designated as the @key{META} shift on your keyboard (if there is |
7a292a7a | 1256 | one) while typing @kbd{?}, or as @key{ESC} followed by @kbd{?}. |
c906108c SS |
1257 | |
1258 | @cindex quotes in commands | |
1259 | @cindex completion of quoted strings | |
1260 | Sometimes the string you need, while logically a ``word'', may contain | |
7a292a7a SS |
1261 | parentheses or other characters that @value{GDBN} normally excludes from |
1262 | its notion of a word. To permit word completion to work in this | |
1263 | situation, you may enclose words in @code{'} (single quote marks) in | |
1264 | @value{GDBN} commands. | |
c906108c | 1265 | |
c906108c SS |
1266 | The most likely situation where you might need this is in typing the |
1267 | name of a C++ function. This is because C++ allows function overloading | |
1268 | (multiple definitions of the same function, distinguished by argument | |
1269 | type). For example, when you want to set a breakpoint you may need to | |
1270 | distinguish whether you mean the version of @code{name} that takes an | |
1271 | @code{int} parameter, @code{name(int)}, or the version that takes a | |
1272 | @code{float} parameter, @code{name(float)}. To use the word-completion | |
1273 | facilities in this situation, type a single quote @code{'} at the | |
1274 | beginning of the function name. This alerts @value{GDBN} that it may need to | |
1275 | consider more information than usual when you press @key{TAB} or | |
1276 | @kbd{M-?} to request word completion: | |
1277 | ||
1278 | @example | |
96a2c332 | 1279 | (@value{GDBP}) b 'bubble( @kbd{M-?} |
c906108c SS |
1280 | bubble(double,double) bubble(int,int) |
1281 | (@value{GDBP}) b 'bubble( | |
1282 | @end example | |
1283 | ||
1284 | In some cases, @value{GDBN} can tell that completing a name requires using | |
1285 | quotes. When this happens, @value{GDBN} inserts the quote for you (while | |
1286 | completing as much as it can) if you do not type the quote in the first | |
1287 | place: | |
1288 | ||
1289 | @example | |
1290 | (@value{GDBP}) b bub @key{TAB} | |
1291 | @exdent @value{GDBN} alters your input line to the following, and rings a bell: | |
1292 | (@value{GDBP}) b 'bubble( | |
1293 | @end example | |
1294 | ||
1295 | @noindent | |
1296 | In general, @value{GDBN} can tell that a quote is needed (and inserts it) if | |
1297 | you have not yet started typing the argument list when you ask for | |
1298 | completion on an overloaded symbol. | |
1299 | ||
d4f3574e | 1300 | For more information about overloaded functions, see @ref{C plus plus |
c906108c SS |
1301 | expressions, ,C++ expressions}. You can use the command @code{set |
1302 | overload-resolution off} to disable overload resolution; | |
d4f3574e | 1303 | see @ref{Debugging C plus plus, ,@value{GDBN} features for C++}. |
c906108c SS |
1304 | |
1305 | ||
6d2ebf8b | 1306 | @node Help |
c906108c SS |
1307 | @section Getting help |
1308 | @cindex online documentation | |
1309 | @kindex help | |
1310 | ||
5d161b24 | 1311 | You can always ask @value{GDBN} itself for information on its commands, |
c906108c SS |
1312 | using the command @code{help}. |
1313 | ||
1314 | @table @code | |
41afff9a | 1315 | @kindex h @r{(@code{help})} |
c906108c SS |
1316 | @item help |
1317 | @itemx h | |
1318 | You can use @code{help} (abbreviated @code{h}) with no arguments to | |
1319 | display a short list of named classes of commands: | |
1320 | ||
1321 | @smallexample | |
1322 | (@value{GDBP}) help | |
1323 | List of classes of commands: | |
1324 | ||
2df3850c | 1325 | aliases -- Aliases of other commands |
c906108c | 1326 | breakpoints -- Making program stop at certain points |
2df3850c | 1327 | data -- Examining data |
c906108c | 1328 | files -- Specifying and examining files |
2df3850c JM |
1329 | internals -- Maintenance commands |
1330 | obscure -- Obscure features | |
1331 | running -- Running the program | |
1332 | stack -- Examining the stack | |
c906108c SS |
1333 | status -- Status inquiries |
1334 | support -- Support facilities | |
96a2c332 SS |
1335 | tracepoints -- Tracing of program execution without@* |
1336 | stopping the program | |
c906108c | 1337 | user-defined -- User-defined commands |
c906108c | 1338 | |
5d161b24 | 1339 | Type "help" followed by a class name for a list of |
c906108c | 1340 | commands in that class. |
5d161b24 | 1341 | Type "help" followed by command name for full |
c906108c SS |
1342 | documentation. |
1343 | Command name abbreviations are allowed if unambiguous. | |
1344 | (@value{GDBP}) | |
1345 | @end smallexample | |
96a2c332 | 1346 | @c the above line break eliminates huge line overfull... |
c906108c SS |
1347 | |
1348 | @item help @var{class} | |
1349 | Using one of the general help classes as an argument, you can get a | |
1350 | list of the individual commands in that class. For example, here is the | |
1351 | help display for the class @code{status}: | |
1352 | ||
1353 | @smallexample | |
1354 | (@value{GDBP}) help status | |
1355 | Status inquiries. | |
1356 | ||
1357 | List of commands: | |
1358 | ||
1359 | @c Line break in "show" line falsifies real output, but needed | |
1360 | @c to fit in smallbook page size. | |
2df3850c JM |
1361 | info -- Generic command for showing things |
1362 | about the program being debugged | |
1363 | show -- Generic command for showing things | |
1364 | about the debugger | |
c906108c | 1365 | |
5d161b24 | 1366 | Type "help" followed by command name for full |
c906108c SS |
1367 | documentation. |
1368 | Command name abbreviations are allowed if unambiguous. | |
1369 | (@value{GDBP}) | |
1370 | @end smallexample | |
1371 | ||
1372 | @item help @var{command} | |
1373 | With a command name as @code{help} argument, @value{GDBN} displays a | |
1374 | short paragraph on how to use that command. | |
1375 | ||
6837a0a2 DB |
1376 | @kindex apropos |
1377 | @item apropos @var{args} | |
1378 | The @code{apropos @var{args}} command searches through all of the @value{GDBN} | |
1379 | commands, and their documentation, for the regular expression specified in | |
1380 | @var{args}. It prints out all matches found. For example: | |
1381 | ||
1382 | @smallexample | |
1383 | apropos reload | |
1384 | @end smallexample | |
1385 | ||
1386 | @noindent results in: | |
1387 | ||
1388 | @smallexample | |
6d2ebf8b SS |
1389 | @c @group |
1390 | set symbol-reloading -- Set dynamic symbol table reloading | |
1391 | multiple times in one run | |
1392 | show symbol-reloading -- Show dynamic symbol table reloading | |
1393 | multiple times in one run | |
1394 | @c @end group | |
6837a0a2 DB |
1395 | @end smallexample |
1396 | ||
c906108c SS |
1397 | @kindex complete |
1398 | @item complete @var{args} | |
1399 | The @code{complete @var{args}} command lists all the possible completions | |
1400 | for the beginning of a command. Use @var{args} to specify the beginning of the | |
1401 | command you want completed. For example: | |
1402 | ||
1403 | @smallexample | |
1404 | complete i | |
1405 | @end smallexample | |
1406 | ||
1407 | @noindent results in: | |
1408 | ||
1409 | @smallexample | |
1410 | @group | |
2df3850c JM |
1411 | if |
1412 | ignore | |
c906108c SS |
1413 | info |
1414 | inspect | |
c906108c SS |
1415 | @end group |
1416 | @end smallexample | |
1417 | ||
1418 | @noindent This is intended for use by @sc{gnu} Emacs. | |
1419 | @end table | |
1420 | ||
1421 | In addition to @code{help}, you can use the @value{GDBN} commands @code{info} | |
1422 | and @code{show} to inquire about the state of your program, or the state | |
1423 | of @value{GDBN} itself. Each command supports many topics of inquiry; this | |
1424 | manual introduces each of them in the appropriate context. The listings | |
1425 | under @code{info} and under @code{show} in the Index point to | |
1426 | all the sub-commands. @xref{Index}. | |
1427 | ||
1428 | @c @group | |
1429 | @table @code | |
1430 | @kindex info | |
41afff9a | 1431 | @kindex i @r{(@code{info})} |
c906108c SS |
1432 | @item info |
1433 | This command (abbreviated @code{i}) is for describing the state of your | |
1434 | program. For example, you can list the arguments given to your program | |
1435 | with @code{info args}, list the registers currently in use with @code{info | |
1436 | registers}, or list the breakpoints you have set with @code{info breakpoints}. | |
1437 | You can get a complete list of the @code{info} sub-commands with | |
1438 | @w{@code{help info}}. | |
1439 | ||
1440 | @kindex set | |
1441 | @item set | |
5d161b24 | 1442 | You can assign the result of an expression to an environment variable with |
c906108c SS |
1443 | @code{set}. For example, you can set the @value{GDBN} prompt to a $-sign with |
1444 | @code{set prompt $}. | |
1445 | ||
1446 | @kindex show | |
1447 | @item show | |
5d161b24 | 1448 | In contrast to @code{info}, @code{show} is for describing the state of |
c906108c SS |
1449 | @value{GDBN} itself. |
1450 | You can change most of the things you can @code{show}, by using the | |
1451 | related command @code{set}; for example, you can control what number | |
1452 | system is used for displays with @code{set radix}, or simply inquire | |
1453 | which is currently in use with @code{show radix}. | |
1454 | ||
1455 | @kindex info set | |
1456 | To display all the settable parameters and their current | |
1457 | values, you can use @code{show} with no arguments; you may also use | |
1458 | @code{info set}. Both commands produce the same display. | |
1459 | @c FIXME: "info set" violates the rule that "info" is for state of | |
1460 | @c FIXME...program. Ck w/ GNU: "info set" to be called something else, | |
1461 | @c FIXME...or change desc of rule---eg "state of prog and debugging session"? | |
1462 | @end table | |
1463 | @c @end group | |
1464 | ||
1465 | Here are three miscellaneous @code{show} subcommands, all of which are | |
1466 | exceptional in lacking corresponding @code{set} commands: | |
1467 | ||
1468 | @table @code | |
1469 | @kindex show version | |
1470 | @cindex version number | |
1471 | @item show version | |
1472 | Show what version of @value{GDBN} is running. You should include this | |
2df3850c JM |
1473 | information in @value{GDBN} bug-reports. If multiple versions of |
1474 | @value{GDBN} are in use at your site, you may need to determine which | |
1475 | version of @value{GDBN} you are running; as @value{GDBN} evolves, new | |
1476 | commands are introduced, and old ones may wither away. Also, many | |
1477 | system vendors ship variant versions of @value{GDBN}, and there are | |
96a2c332 | 1478 | variant versions of @value{GDBN} in @sc{gnu}/Linux distributions as well. |
2df3850c JM |
1479 | The version number is the same as the one announced when you start |
1480 | @value{GDBN}. | |
c906108c SS |
1481 | |
1482 | @kindex show copying | |
1483 | @item show copying | |
1484 | Display information about permission for copying @value{GDBN}. | |
1485 | ||
1486 | @kindex show warranty | |
1487 | @item show warranty | |
2df3850c | 1488 | Display the @sc{gnu} ``NO WARRANTY'' statement, or a warranty, |
96a2c332 | 1489 | if your version of @value{GDBN} comes with one. |
2df3850c | 1490 | |
c906108c SS |
1491 | @end table |
1492 | ||
6d2ebf8b | 1493 | @node Running |
c906108c SS |
1494 | @chapter Running Programs Under @value{GDBN} |
1495 | ||
1496 | When you run a program under @value{GDBN}, you must first generate | |
1497 | debugging information when you compile it. | |
7a292a7a SS |
1498 | |
1499 | You may start @value{GDBN} with its arguments, if any, in an environment | |
1500 | of your choice. If you are doing native debugging, you may redirect | |
1501 | your program's input and output, debug an already running process, or | |
1502 | kill a child process. | |
c906108c SS |
1503 | |
1504 | @menu | |
1505 | * Compilation:: Compiling for debugging | |
1506 | * Starting:: Starting your program | |
c906108c SS |
1507 | * Arguments:: Your program's arguments |
1508 | * Environment:: Your program's environment | |
c906108c SS |
1509 | |
1510 | * Working Directory:: Your program's working directory | |
1511 | * Input/Output:: Your program's input and output | |
1512 | * Attach:: Debugging an already-running process | |
1513 | * Kill Process:: Killing the child process | |
c906108c SS |
1514 | |
1515 | * Threads:: Debugging programs with multiple threads | |
1516 | * Processes:: Debugging programs with multiple processes | |
1517 | @end menu | |
1518 | ||
6d2ebf8b | 1519 | @node Compilation |
c906108c SS |
1520 | @section Compiling for debugging |
1521 | ||
1522 | In order to debug a program effectively, you need to generate | |
1523 | debugging information when you compile it. This debugging information | |
1524 | is stored in the object file; it describes the data type of each | |
1525 | variable or function and the correspondence between source line numbers | |
1526 | and addresses in the executable code. | |
1527 | ||
1528 | To request debugging information, specify the @samp{-g} option when you run | |
1529 | the compiler. | |
1530 | ||
1531 | Many C compilers are unable to handle the @samp{-g} and @samp{-O} | |
1532 | options together. Using those compilers, you cannot generate optimized | |
1533 | executables containing debugging information. | |
1534 | ||
53a5351d JM |
1535 | @value{NGCC}, the @sc{gnu} C compiler, supports @samp{-g} with or |
1536 | without @samp{-O}, making it possible to debug optimized code. We | |
1537 | recommend that you @emph{always} use @samp{-g} whenever you compile a | |
1538 | program. You may think your program is correct, but there is no sense | |
1539 | in pushing your luck. | |
c906108c SS |
1540 | |
1541 | @cindex optimized code, debugging | |
1542 | @cindex debugging optimized code | |
1543 | When you debug a program compiled with @samp{-g -O}, remember that the | |
1544 | optimizer is rearranging your code; the debugger shows you what is | |
1545 | really there. Do not be too surprised when the execution path does not | |
1546 | exactly match your source file! An extreme example: if you define a | |
1547 | variable, but never use it, @value{GDBN} never sees that | |
1548 | variable---because the compiler optimizes it out of existence. | |
1549 | ||
1550 | Some things do not work as well with @samp{-g -O} as with just | |
1551 | @samp{-g}, particularly on machines with instruction scheduling. If in | |
1552 | doubt, recompile with @samp{-g} alone, and if this fixes the problem, | |
1553 | please report it to us as a bug (including a test case!). | |
1554 | ||
1555 | Older versions of the @sc{gnu} C compiler permitted a variant option | |
1556 | @w{@samp{-gg}} for debugging information. @value{GDBN} no longer supports this | |
1557 | format; if your @sc{gnu} C compiler has this option, do not use it. | |
1558 | ||
1559 | @need 2000 | |
6d2ebf8b | 1560 | @node Starting |
c906108c SS |
1561 | @section Starting your program |
1562 | @cindex starting | |
1563 | @cindex running | |
1564 | ||
1565 | @table @code | |
1566 | @kindex run | |
41afff9a | 1567 | @kindex r @r{(@code{run})} |
c906108c SS |
1568 | @item run |
1569 | @itemx r | |
7a292a7a SS |
1570 | Use the @code{run} command to start your program under @value{GDBN}. |
1571 | You must first specify the program name (except on VxWorks) with an | |
1572 | argument to @value{GDBN} (@pxref{Invocation, ,Getting In and Out of | |
1573 | @value{GDBN}}), or by using the @code{file} or @code{exec-file} command | |
1574 | (@pxref{Files, ,Commands to specify files}). | |
c906108c SS |
1575 | |
1576 | @end table | |
1577 | ||
c906108c SS |
1578 | If you are running your program in an execution environment that |
1579 | supports processes, @code{run} creates an inferior process and makes | |
1580 | that process run your program. (In environments without processes, | |
1581 | @code{run} jumps to the start of your program.) | |
1582 | ||
1583 | The execution of a program is affected by certain information it | |
1584 | receives from its superior. @value{GDBN} provides ways to specify this | |
1585 | information, which you must do @emph{before} starting your program. (You | |
1586 | can change it after starting your program, but such changes only affect | |
1587 | your program the next time you start it.) This information may be | |
1588 | divided into four categories: | |
1589 | ||
1590 | @table @asis | |
1591 | @item The @emph{arguments.} | |
1592 | Specify the arguments to give your program as the arguments of the | |
1593 | @code{run} command. If a shell is available on your target, the shell | |
1594 | is used to pass the arguments, so that you may use normal conventions | |
1595 | (such as wildcard expansion or variable substitution) in describing | |
1596 | the arguments. | |
1597 | In Unix systems, you can control which shell is used with the | |
1598 | @code{SHELL} environment variable. | |
1599 | @xref{Arguments, ,Your program's arguments}. | |
1600 | ||
1601 | @item The @emph{environment.} | |
1602 | Your program normally inherits its environment from @value{GDBN}, but you can | |
1603 | use the @value{GDBN} commands @code{set environment} and @code{unset | |
1604 | environment} to change parts of the environment that affect | |
1605 | your program. @xref{Environment, ,Your program's environment}. | |
1606 | ||
1607 | @item The @emph{working directory.} | |
1608 | Your program inherits its working directory from @value{GDBN}. You can set | |
1609 | the @value{GDBN} working directory with the @code{cd} command in @value{GDBN}. | |
1610 | @xref{Working Directory, ,Your program's working directory}. | |
1611 | ||
1612 | @item The @emph{standard input and output.} | |
1613 | Your program normally uses the same device for standard input and | |
1614 | standard output as @value{GDBN} is using. You can redirect input and output | |
1615 | in the @code{run} command line, or you can use the @code{tty} command to | |
1616 | set a different device for your program. | |
1617 | @xref{Input/Output, ,Your program's input and output}. | |
1618 | ||
1619 | @cindex pipes | |
1620 | @emph{Warning:} While input and output redirection work, you cannot use | |
1621 | pipes to pass the output of the program you are debugging to another | |
1622 | program; if you attempt this, @value{GDBN} is likely to wind up debugging the | |
1623 | wrong program. | |
1624 | @end table | |
c906108c SS |
1625 | |
1626 | When you issue the @code{run} command, your program begins to execute | |
1627 | immediately. @xref{Stopping, ,Stopping and continuing}, for discussion | |
1628 | of how to arrange for your program to stop. Once your program has | |
1629 | stopped, you may call functions in your program, using the @code{print} | |
1630 | or @code{call} commands. @xref{Data, ,Examining Data}. | |
1631 | ||
1632 | If the modification time of your symbol file has changed since the last | |
1633 | time @value{GDBN} read its symbols, @value{GDBN} discards its symbol | |
1634 | table, and reads it again. When it does this, @value{GDBN} tries to retain | |
1635 | your current breakpoints. | |
1636 | ||
6d2ebf8b | 1637 | @node Arguments |
c906108c SS |
1638 | @section Your program's arguments |
1639 | ||
1640 | @cindex arguments (to your program) | |
1641 | The arguments to your program can be specified by the arguments of the | |
5d161b24 | 1642 | @code{run} command. |
c906108c SS |
1643 | They are passed to a shell, which expands wildcard characters and |
1644 | performs redirection of I/O, and thence to your program. Your | |
1645 | @code{SHELL} environment variable (if it exists) specifies what shell | |
1646 | @value{GDBN} uses. If you do not define @code{SHELL}, @value{GDBN} uses | |
d4f3574e SS |
1647 | the default shell (@file{/bin/sh} on Unix). |
1648 | ||
1649 | On non-Unix systems, the program is usually invoked directly by | |
1650 | @value{GDBN}, which emulates I/O redirection via the appropriate system | |
1651 | calls, and the wildcard characters are expanded by the startup code of | |
1652 | the program, not by the shell. | |
c906108c SS |
1653 | |
1654 | @code{run} with no arguments uses the same arguments used by the previous | |
1655 | @code{run}, or those set by the @code{set args} command. | |
1656 | ||
c906108c | 1657 | @table @code |
41afff9a | 1658 | @kindex set args |
c906108c SS |
1659 | @item set args |
1660 | Specify the arguments to be used the next time your program is run. If | |
1661 | @code{set args} has no arguments, @code{run} executes your program | |
1662 | with no arguments. Once you have run your program with arguments, | |
1663 | using @code{set args} before the next @code{run} is the only way to run | |
1664 | it again without arguments. | |
1665 | ||
1666 | @kindex show args | |
1667 | @item show args | |
1668 | Show the arguments to give your program when it is started. | |
1669 | @end table | |
1670 | ||
6d2ebf8b | 1671 | @node Environment |
c906108c SS |
1672 | @section Your program's environment |
1673 | ||
1674 | @cindex environment (of your program) | |
1675 | The @dfn{environment} consists of a set of environment variables and | |
1676 | their values. Environment variables conventionally record such things as | |
1677 | your user name, your home directory, your terminal type, and your search | |
1678 | path for programs to run. Usually you set up environment variables with | |
1679 | the shell and they are inherited by all the other programs you run. When | |
1680 | debugging, it can be useful to try running your program with a modified | |
1681 | environment without having to start @value{GDBN} over again. | |
1682 | ||
1683 | @table @code | |
1684 | @kindex path | |
1685 | @item path @var{directory} | |
1686 | Add @var{directory} to the front of the @code{PATH} environment variable | |
17cc6a06 EZ |
1687 | (the search path for executables) that will be passed to your program. |
1688 | The value of @code{PATH} used by @value{GDBN} does not change. | |
d4f3574e SS |
1689 | You may specify several directory names, separated by whitespace or by a |
1690 | system-dependent separator character (@samp{:} on Unix, @samp{;} on | |
1691 | MS-DOS and MS-Windows). If @var{directory} is already in the path, it | |
1692 | is moved to the front, so it is searched sooner. | |
c906108c SS |
1693 | |
1694 | You can use the string @samp{$cwd} to refer to whatever is the current | |
1695 | working directory at the time @value{GDBN} searches the path. If you | |
1696 | use @samp{.} instead, it refers to the directory where you executed the | |
1697 | @code{path} command. @value{GDBN} replaces @samp{.} in the | |
1698 | @var{directory} argument (with the current path) before adding | |
1699 | @var{directory} to the search path. | |
1700 | @c 'path' is explicitly nonrepeatable, but RMS points out it is silly to | |
1701 | @c document that, since repeating it would be a no-op. | |
1702 | ||
1703 | @kindex show paths | |
1704 | @item show paths | |
1705 | Display the list of search paths for executables (the @code{PATH} | |
1706 | environment variable). | |
1707 | ||
1708 | @kindex show environment | |
1709 | @item show environment @r{[}@var{varname}@r{]} | |
1710 | Print the value of environment variable @var{varname} to be given to | |
1711 | your program when it starts. If you do not supply @var{varname}, | |
1712 | print the names and values of all environment variables to be given to | |
1713 | your program. You can abbreviate @code{environment} as @code{env}. | |
1714 | ||
1715 | @kindex set environment | |
53a5351d | 1716 | @item set environment @var{varname} @r{[}=@var{value}@r{]} |
c906108c SS |
1717 | Set environment variable @var{varname} to @var{value}. The value |
1718 | changes for your program only, not for @value{GDBN} itself. @var{value} may | |
1719 | be any string; the values of environment variables are just strings, and | |
1720 | any interpretation is supplied by your program itself. The @var{value} | |
1721 | parameter is optional; if it is eliminated, the variable is set to a | |
1722 | null value. | |
1723 | @c "any string" here does not include leading, trailing | |
1724 | @c blanks. Gnu asks: does anyone care? | |
1725 | ||
1726 | For example, this command: | |
1727 | ||
1728 | @example | |
1729 | set env USER = foo | |
1730 | @end example | |
1731 | ||
1732 | @noindent | |
d4f3574e | 1733 | tells the debugged program, when subsequently run, that its user is named |
c906108c SS |
1734 | @samp{foo}. (The spaces around @samp{=} are used for clarity here; they |
1735 | are not actually required.) | |
1736 | ||
1737 | @kindex unset environment | |
1738 | @item unset environment @var{varname} | |
1739 | Remove variable @var{varname} from the environment to be passed to your | |
1740 | program. This is different from @samp{set env @var{varname} =}; | |
1741 | @code{unset environment} removes the variable from the environment, | |
1742 | rather than assigning it an empty value. | |
1743 | @end table | |
1744 | ||
d4f3574e SS |
1745 | @emph{Warning:} On Unix systems, @value{GDBN} runs your program using |
1746 | the shell indicated | |
c906108c SS |
1747 | by your @code{SHELL} environment variable if it exists (or |
1748 | @code{/bin/sh} if not). If your @code{SHELL} variable names a shell | |
1749 | that runs an initialization file---such as @file{.cshrc} for C-shell, or | |
1750 | @file{.bashrc} for BASH---any variables you set in that file affect | |
1751 | your program. You may wish to move setting of environment variables to | |
1752 | files that are only run when you sign on, such as @file{.login} or | |
1753 | @file{.profile}. | |
1754 | ||
6d2ebf8b | 1755 | @node Working Directory |
c906108c SS |
1756 | @section Your program's working directory |
1757 | ||
1758 | @cindex working directory (of your program) | |
1759 | Each time you start your program with @code{run}, it inherits its | |
1760 | working directory from the current working directory of @value{GDBN}. | |
1761 | The @value{GDBN} working directory is initially whatever it inherited | |
1762 | from its parent process (typically the shell), but you can specify a new | |
1763 | working directory in @value{GDBN} with the @code{cd} command. | |
1764 | ||
1765 | The @value{GDBN} working directory also serves as a default for the commands | |
1766 | that specify files for @value{GDBN} to operate on. @xref{Files, ,Commands to | |
1767 | specify files}. | |
1768 | ||
1769 | @table @code | |
1770 | @kindex cd | |
1771 | @item cd @var{directory} | |
1772 | Set the @value{GDBN} working directory to @var{directory}. | |
1773 | ||
1774 | @kindex pwd | |
1775 | @item pwd | |
1776 | Print the @value{GDBN} working directory. | |
1777 | @end table | |
1778 | ||
6d2ebf8b | 1779 | @node Input/Output |
c906108c SS |
1780 | @section Your program's input and output |
1781 | ||
1782 | @cindex redirection | |
1783 | @cindex i/o | |
1784 | @cindex terminal | |
1785 | By default, the program you run under @value{GDBN} does input and output to | |
5d161b24 | 1786 | the same terminal that @value{GDBN} uses. @value{GDBN} switches the terminal |
c906108c SS |
1787 | to its own terminal modes to interact with you, but it records the terminal |
1788 | modes your program was using and switches back to them when you continue | |
1789 | running your program. | |
1790 | ||
1791 | @table @code | |
1792 | @kindex info terminal | |
1793 | @item info terminal | |
1794 | Displays information recorded by @value{GDBN} about the terminal modes your | |
1795 | program is using. | |
1796 | @end table | |
1797 | ||
1798 | You can redirect your program's input and/or output using shell | |
1799 | redirection with the @code{run} command. For example, | |
1800 | ||
1801 | @example | |
1802 | run > outfile | |
1803 | @end example | |
1804 | ||
1805 | @noindent | |
1806 | starts your program, diverting its output to the file @file{outfile}. | |
1807 | ||
1808 | @kindex tty | |
1809 | @cindex controlling terminal | |
1810 | Another way to specify where your program should do input and output is | |
1811 | with the @code{tty} command. This command accepts a file name as | |
1812 | argument, and causes this file to be the default for future @code{run} | |
1813 | commands. It also resets the controlling terminal for the child | |
1814 | process, for future @code{run} commands. For example, | |
1815 | ||
1816 | @example | |
1817 | tty /dev/ttyb | |
1818 | @end example | |
1819 | ||
1820 | @noindent | |
1821 | directs that processes started with subsequent @code{run} commands | |
1822 | default to do input and output on the terminal @file{/dev/ttyb} and have | |
1823 | that as their controlling terminal. | |
1824 | ||
1825 | An explicit redirection in @code{run} overrides the @code{tty} command's | |
1826 | effect on the input/output device, but not its effect on the controlling | |
1827 | terminal. | |
1828 | ||
1829 | When you use the @code{tty} command or redirect input in the @code{run} | |
1830 | command, only the input @emph{for your program} is affected. The input | |
1831 | for @value{GDBN} still comes from your terminal. | |
1832 | ||
6d2ebf8b | 1833 | @node Attach |
c906108c SS |
1834 | @section Debugging an already-running process |
1835 | @kindex attach | |
1836 | @cindex attach | |
1837 | ||
1838 | @table @code | |
1839 | @item attach @var{process-id} | |
1840 | This command attaches to a running process---one that was started | |
1841 | outside @value{GDBN}. (@code{info files} shows your active | |
1842 | targets.) The command takes as argument a process ID. The usual way to | |
1843 | find out the process-id of a Unix process is with the @code{ps} utility, | |
1844 | or with the @samp{jobs -l} shell command. | |
1845 | ||
1846 | @code{attach} does not repeat if you press @key{RET} a second time after | |
1847 | executing the command. | |
1848 | @end table | |
1849 | ||
1850 | To use @code{attach}, your program must be running in an environment | |
1851 | which supports processes; for example, @code{attach} does not work for | |
1852 | programs on bare-board targets that lack an operating system. You must | |
1853 | also have permission to send the process a signal. | |
1854 | ||
1855 | When you use @code{attach}, the debugger finds the program running in | |
1856 | the process first by looking in the current working directory, then (if | |
1857 | the program is not found) by using the source file search path | |
1858 | (@pxref{Source Path, ,Specifying source directories}). You can also use | |
1859 | the @code{file} command to load the program. @xref{Files, ,Commands to | |
1860 | Specify Files}. | |
1861 | ||
1862 | The first thing @value{GDBN} does after arranging to debug the specified | |
1863 | process is to stop it. You can examine and modify an attached process | |
53a5351d JM |
1864 | with all the @value{GDBN} commands that are ordinarily available when |
1865 | you start processes with @code{run}. You can insert breakpoints; you | |
1866 | can step and continue; you can modify storage. If you would rather the | |
1867 | process continue running, you may use the @code{continue} command after | |
c906108c SS |
1868 | attaching @value{GDBN} to the process. |
1869 | ||
1870 | @table @code | |
1871 | @kindex detach | |
1872 | @item detach | |
1873 | When you have finished debugging the attached process, you can use the | |
1874 | @code{detach} command to release it from @value{GDBN} control. Detaching | |
1875 | the process continues its execution. After the @code{detach} command, | |
1876 | that process and @value{GDBN} become completely independent once more, and you | |
1877 | are ready to @code{attach} another process or start one with @code{run}. | |
1878 | @code{detach} does not repeat if you press @key{RET} again after | |
1879 | executing the command. | |
1880 | @end table | |
1881 | ||
1882 | If you exit @value{GDBN} or use the @code{run} command while you have an | |
1883 | attached process, you kill that process. By default, @value{GDBN} asks | |
1884 | for confirmation if you try to do either of these things; you can | |
1885 | control whether or not you need to confirm by using the @code{set | |
1886 | confirm} command (@pxref{Messages/Warnings, ,Optional warnings and | |
1887 | messages}). | |
1888 | ||
6d2ebf8b | 1889 | @node Kill Process |
c906108c | 1890 | @section Killing the child process |
c906108c SS |
1891 | |
1892 | @table @code | |
1893 | @kindex kill | |
1894 | @item kill | |
1895 | Kill the child process in which your program is running under @value{GDBN}. | |
1896 | @end table | |
1897 | ||
1898 | This command is useful if you wish to debug a core dump instead of a | |
1899 | running process. @value{GDBN} ignores any core dump file while your program | |
1900 | is running. | |
1901 | ||
1902 | On some operating systems, a program cannot be executed outside @value{GDBN} | |
1903 | while you have breakpoints set on it inside @value{GDBN}. You can use the | |
1904 | @code{kill} command in this situation to permit running your program | |
1905 | outside the debugger. | |
1906 | ||
1907 | The @code{kill} command is also useful if you wish to recompile and | |
1908 | relink your program, since on many systems it is impossible to modify an | |
1909 | executable file while it is running in a process. In this case, when you | |
1910 | next type @code{run}, @value{GDBN} notices that the file has changed, and | |
1911 | reads the symbol table again (while trying to preserve your current | |
1912 | breakpoint settings). | |
1913 | ||
6d2ebf8b | 1914 | @node Threads |
c906108c | 1915 | @section Debugging programs with multiple threads |
c906108c SS |
1916 | |
1917 | @cindex threads of execution | |
1918 | @cindex multiple threads | |
1919 | @cindex switching threads | |
1920 | In some operating systems, such as HP-UX and Solaris, a single program | |
1921 | may have more than one @dfn{thread} of execution. The precise semantics | |
1922 | of threads differ from one operating system to another, but in general | |
1923 | the threads of a single program are akin to multiple processes---except | |
1924 | that they share one address space (that is, they can all examine and | |
1925 | modify the same variables). On the other hand, each thread has its own | |
1926 | registers and execution stack, and perhaps private memory. | |
1927 | ||
1928 | @value{GDBN} provides these facilities for debugging multi-thread | |
1929 | programs: | |
1930 | ||
1931 | @itemize @bullet | |
1932 | @item automatic notification of new threads | |
1933 | @item @samp{thread @var{threadno}}, a command to switch among threads | |
1934 | @item @samp{info threads}, a command to inquire about existing threads | |
5d161b24 | 1935 | @item @samp{thread apply [@var{threadno}] [@var{all}] @var{args}}, |
c906108c SS |
1936 | a command to apply a command to a list of threads |
1937 | @item thread-specific breakpoints | |
1938 | @end itemize | |
1939 | ||
c906108c SS |
1940 | @quotation |
1941 | @emph{Warning:} These facilities are not yet available on every | |
1942 | @value{GDBN} configuration where the operating system supports threads. | |
1943 | If your @value{GDBN} does not support threads, these commands have no | |
1944 | effect. For example, a system without thread support shows no output | |
1945 | from @samp{info threads}, and always rejects the @code{thread} command, | |
1946 | like this: | |
1947 | ||
1948 | @smallexample | |
1949 | (@value{GDBP}) info threads | |
1950 | (@value{GDBP}) thread 1 | |
1951 | Thread ID 1 not known. Use the "info threads" command to | |
1952 | see the IDs of currently known threads. | |
1953 | @end smallexample | |
1954 | @c FIXME to implementors: how hard would it be to say "sorry, this GDB | |
1955 | @c doesn't support threads"? | |
1956 | @end quotation | |
c906108c SS |
1957 | |
1958 | @cindex focus of debugging | |
1959 | @cindex current thread | |
1960 | The @value{GDBN} thread debugging facility allows you to observe all | |
1961 | threads while your program runs---but whenever @value{GDBN} takes | |
1962 | control, one thread in particular is always the focus of debugging. | |
1963 | This thread is called the @dfn{current thread}. Debugging commands show | |
1964 | program information from the perspective of the current thread. | |
1965 | ||
41afff9a | 1966 | @cindex @code{New} @var{systag} message |
c906108c SS |
1967 | @cindex thread identifier (system) |
1968 | @c FIXME-implementors!! It would be more helpful if the [New...] message | |
1969 | @c included GDB's numeric thread handle, so you could just go to that | |
1970 | @c thread without first checking `info threads'. | |
1971 | Whenever @value{GDBN} detects a new thread in your program, it displays | |
1972 | the target system's identification for the thread with a message in the | |
1973 | form @samp{[New @var{systag}]}. @var{systag} is a thread identifier | |
1974 | whose form varies depending on the particular system. For example, on | |
1975 | LynxOS, you might see | |
1976 | ||
1977 | @example | |
1978 | [New process 35 thread 27] | |
1979 | @end example | |
1980 | ||
1981 | @noindent | |
1982 | when @value{GDBN} notices a new thread. In contrast, on an SGI system, | |
1983 | the @var{systag} is simply something like @samp{process 368}, with no | |
1984 | further qualifier. | |
1985 | ||
1986 | @c FIXME!! (1) Does the [New...] message appear even for the very first | |
1987 | @c thread of a program, or does it only appear for the | |
1988 | @c second---i.e., when it becomes obvious we have a multithread | |
1989 | @c program? | |
1990 | @c (2) *Is* there necessarily a first thread always? Or do some | |
1991 | @c multithread systems permit starting a program with multiple | |
5d161b24 | 1992 | @c threads ab initio? |
c906108c SS |
1993 | |
1994 | @cindex thread number | |
1995 | @cindex thread identifier (GDB) | |
1996 | For debugging purposes, @value{GDBN} associates its own thread | |
1997 | number---always a single integer---with each thread in your program. | |
1998 | ||
1999 | @table @code | |
2000 | @kindex info threads | |
2001 | @item info threads | |
2002 | Display a summary of all threads currently in your | |
2003 | program. @value{GDBN} displays for each thread (in this order): | |
2004 | ||
2005 | @enumerate | |
2006 | @item the thread number assigned by @value{GDBN} | |
2007 | ||
2008 | @item the target system's thread identifier (@var{systag}) | |
2009 | ||
2010 | @item the current stack frame summary for that thread | |
2011 | @end enumerate | |
2012 | ||
2013 | @noindent | |
2014 | An asterisk @samp{*} to the left of the @value{GDBN} thread number | |
2015 | indicates the current thread. | |
2016 | ||
5d161b24 | 2017 | For example, |
c906108c SS |
2018 | @end table |
2019 | @c end table here to get a little more width for example | |
2020 | ||
2021 | @smallexample | |
2022 | (@value{GDBP}) info threads | |
2023 | 3 process 35 thread 27 0x34e5 in sigpause () | |
2024 | 2 process 35 thread 23 0x34e5 in sigpause () | |
2025 | * 1 process 35 thread 13 main (argc=1, argv=0x7ffffff8) | |
2026 | at threadtest.c:68 | |
2027 | @end smallexample | |
53a5351d JM |
2028 | |
2029 | On HP-UX systems: | |
c906108c SS |
2030 | |
2031 | @cindex thread number | |
2032 | @cindex thread identifier (GDB) | |
2033 | For debugging purposes, @value{GDBN} associates its own thread | |
2034 | number---a small integer assigned in thread-creation order---with each | |
2035 | thread in your program. | |
2036 | ||
41afff9a EZ |
2037 | @cindex @code{New} @var{systag} message, on HP-UX |
2038 | @cindex thread identifier (system), on HP-UX | |
c906108c SS |
2039 | @c FIXME-implementors!! It would be more helpful if the [New...] message |
2040 | @c included GDB's numeric thread handle, so you could just go to that | |
2041 | @c thread without first checking `info threads'. | |
2042 | Whenever @value{GDBN} detects a new thread in your program, it displays | |
2043 | both @value{GDBN}'s thread number and the target system's identification for the thread with a message in the | |
2044 | form @samp{[New @var{systag}]}. @var{systag} is a thread identifier | |
2045 | whose form varies depending on the particular system. For example, on | |
2046 | HP-UX, you see | |
2047 | ||
2048 | @example | |
2049 | [New thread 2 (system thread 26594)] | |
2050 | @end example | |
2051 | ||
2052 | @noindent | |
5d161b24 | 2053 | when @value{GDBN} notices a new thread. |
c906108c SS |
2054 | |
2055 | @table @code | |
2056 | @kindex info threads | |
2057 | @item info threads | |
2058 | Display a summary of all threads currently in your | |
2059 | program. @value{GDBN} displays for each thread (in this order): | |
2060 | ||
2061 | @enumerate | |
2062 | @item the thread number assigned by @value{GDBN} | |
2063 | ||
2064 | @item the target system's thread identifier (@var{systag}) | |
2065 | ||
2066 | @item the current stack frame summary for that thread | |
2067 | @end enumerate | |
2068 | ||
2069 | @noindent | |
2070 | An asterisk @samp{*} to the left of the @value{GDBN} thread number | |
2071 | indicates the current thread. | |
2072 | ||
5d161b24 | 2073 | For example, |
c906108c SS |
2074 | @end table |
2075 | @c end table here to get a little more width for example | |
2076 | ||
2077 | @example | |
2078 | (@value{GDBP}) info threads | |
6d2ebf8b SS |
2079 | * 3 system thread 26607 worker (wptr=0x7b09c318 "@@") \@* |
2080 | at quicksort.c:137 | |
2081 | 2 system thread 26606 0x7b0030d8 in __ksleep () \@* | |
2082 | from /usr/lib/libc.2 | |
2083 | 1 system thread 27905 0x7b003498 in _brk () \@* | |
2084 | from /usr/lib/libc.2 | |
c906108c | 2085 | @end example |
c906108c SS |
2086 | |
2087 | @table @code | |
2088 | @kindex thread @var{threadno} | |
2089 | @item thread @var{threadno} | |
2090 | Make thread number @var{threadno} the current thread. The command | |
2091 | argument @var{threadno} is the internal @value{GDBN} thread number, as | |
2092 | shown in the first field of the @samp{info threads} display. | |
2093 | @value{GDBN} responds by displaying the system identifier of the thread | |
2094 | you selected, and its current stack frame summary: | |
2095 | ||
2096 | @smallexample | |
2097 | @c FIXME!! This example made up; find a @value{GDBN} w/threads and get real one | |
2098 | (@value{GDBP}) thread 2 | |
c906108c | 2099 | [Switching to process 35 thread 23] |
c906108c SS |
2100 | 0x34e5 in sigpause () |
2101 | @end smallexample | |
2102 | ||
2103 | @noindent | |
2104 | As with the @samp{[New @dots{}]} message, the form of the text after | |
2105 | @samp{Switching to} depends on your system's conventions for identifying | |
5d161b24 | 2106 | threads. |
c906108c SS |
2107 | |
2108 | @kindex thread apply | |
2109 | @item thread apply [@var{threadno}] [@var{all}] @var{args} | |
2110 | The @code{thread apply} command allows you to apply a command to one or | |
2111 | more threads. Specify the numbers of the threads that you want affected | |
2112 | with the command argument @var{threadno}. @var{threadno} is the internal | |
2113 | @value{GDBN} thread number, as shown in the first field of the @samp{info | |
5d161b24 DB |
2114 | threads} display. To apply a command to all threads, use |
2115 | @code{thread apply all} @var{args}. | |
c906108c SS |
2116 | @end table |
2117 | ||
2118 | @cindex automatic thread selection | |
2119 | @cindex switching threads automatically | |
2120 | @cindex threads, automatic switching | |
2121 | Whenever @value{GDBN} stops your program, due to a breakpoint or a | |
2122 | signal, it automatically selects the thread where that breakpoint or | |
2123 | signal happened. @value{GDBN} alerts you to the context switch with a | |
2124 | message of the form @samp{[Switching to @var{systag}]} to identify the | |
2125 | thread. | |
2126 | ||
2127 | @xref{Thread Stops,,Stopping and starting multi-thread programs}, for | |
2128 | more information about how @value{GDBN} behaves when you stop and start | |
2129 | programs with multiple threads. | |
2130 | ||
2131 | @xref{Set Watchpoints,,Setting watchpoints}, for information about | |
2132 | watchpoints in programs with multiple threads. | |
c906108c | 2133 | |
6d2ebf8b | 2134 | @node Processes |
c906108c SS |
2135 | @section Debugging programs with multiple processes |
2136 | ||
2137 | @cindex fork, debugging programs which call | |
2138 | @cindex multiple processes | |
2139 | @cindex processes, multiple | |
53a5351d JM |
2140 | On most systems, @value{GDBN} has no special support for debugging |
2141 | programs which create additional processes using the @code{fork} | |
2142 | function. When a program forks, @value{GDBN} will continue to debug the | |
2143 | parent process and the child process will run unimpeded. If you have | |
2144 | set a breakpoint in any code which the child then executes, the child | |
2145 | will get a @code{SIGTRAP} signal which (unless it catches the signal) | |
2146 | will cause it to terminate. | |
c906108c SS |
2147 | |
2148 | However, if you want to debug the child process there is a workaround | |
2149 | which isn't too painful. Put a call to @code{sleep} in the code which | |
2150 | the child process executes after the fork. It may be useful to sleep | |
2151 | only if a certain environment variable is set, or a certain file exists, | |
2152 | so that the delay need not occur when you don't want to run @value{GDBN} | |
2153 | on the child. While the child is sleeping, use the @code{ps} program to | |
2154 | get its process ID. Then tell @value{GDBN} (a new invocation of | |
2155 | @value{GDBN} if you are also debugging the parent process) to attach to | |
d4f3574e | 2156 | the child process (@pxref{Attach}). From that point on you can debug |
c906108c | 2157 | the child process just like any other process which you attached to. |
c906108c | 2158 | |
53a5351d JM |
2159 | On HP-UX (11.x and later only?), @value{GDBN} provides support for |
2160 | debugging programs that create additional processes using the | |
2161 | @code{fork} or @code{vfork} function. | |
c906108c SS |
2162 | |
2163 | By default, when a program forks, @value{GDBN} will continue to debug | |
2164 | the parent process and the child process will run unimpeded. | |
2165 | ||
2166 | If you want to follow the child process instead of the parent process, | |
2167 | use the command @w{@code{set follow-fork-mode}}. | |
2168 | ||
2169 | @table @code | |
2170 | @kindex set follow-fork-mode | |
2171 | @item set follow-fork-mode @var{mode} | |
2172 | Set the debugger response to a program call of @code{fork} or | |
2173 | @code{vfork}. A call to @code{fork} or @code{vfork} creates a new | |
2174 | process. The @var{mode} can be: | |
2175 | ||
2176 | @table @code | |
2177 | @item parent | |
2178 | The original process is debugged after a fork. The child process runs | |
2df3850c | 2179 | unimpeded. This is the default. |
c906108c SS |
2180 | |
2181 | @item child | |
2182 | The new process is debugged after a fork. The parent process runs | |
2183 | unimpeded. | |
2184 | ||
2185 | @item ask | |
2186 | The debugger will ask for one of the above choices. | |
2187 | @end table | |
2188 | ||
2189 | @item show follow-fork-mode | |
2df3850c | 2190 | Display the current debugger response to a @code{fork} or @code{vfork} call. |
c906108c SS |
2191 | @end table |
2192 | ||
2193 | If you ask to debug a child process and a @code{vfork} is followed by an | |
2194 | @code{exec}, @value{GDBN} executes the new target up to the first | |
2195 | breakpoint in the new target. If you have a breakpoint set on | |
2196 | @code{main} in your original program, the breakpoint will also be set on | |
2197 | the child process's @code{main}. | |
2198 | ||
2199 | When a child process is spawned by @code{vfork}, you cannot debug the | |
2200 | child or parent until an @code{exec} call completes. | |
2201 | ||
2202 | If you issue a @code{run} command to @value{GDBN} after an @code{exec} | |
2203 | call executes, the new target restarts. To restart the parent process, | |
2204 | use the @code{file} command with the parent executable name as its | |
2205 | argument. | |
2206 | ||
2207 | You can use the @code{catch} command to make @value{GDBN} stop whenever | |
2208 | a @code{fork}, @code{vfork}, or @code{exec} call is made. @xref{Set | |
2209 | Catchpoints, ,Setting catchpoints}. | |
c906108c | 2210 | |
6d2ebf8b | 2211 | @node Stopping |
c906108c SS |
2212 | @chapter Stopping and Continuing |
2213 | ||
2214 | The principal purposes of using a debugger are so that you can stop your | |
2215 | program before it terminates; or so that, if your program runs into | |
2216 | trouble, you can investigate and find out why. | |
2217 | ||
7a292a7a SS |
2218 | Inside @value{GDBN}, your program may stop for any of several reasons, |
2219 | such as a signal, a breakpoint, or reaching a new line after a | |
2220 | @value{GDBN} command such as @code{step}. You may then examine and | |
2221 | change variables, set new breakpoints or remove old ones, and then | |
2222 | continue execution. Usually, the messages shown by @value{GDBN} provide | |
2223 | ample explanation of the status of your program---but you can also | |
2224 | explicitly request this information at any time. | |
c906108c SS |
2225 | |
2226 | @table @code | |
2227 | @kindex info program | |
2228 | @item info program | |
2229 | Display information about the status of your program: whether it is | |
7a292a7a | 2230 | running or not, what process it is, and why it stopped. |
c906108c SS |
2231 | @end table |
2232 | ||
2233 | @menu | |
2234 | * Breakpoints:: Breakpoints, watchpoints, and catchpoints | |
2235 | * Continuing and Stepping:: Resuming execution | |
c906108c | 2236 | * Signals:: Signals |
c906108c | 2237 | * Thread Stops:: Stopping and starting multi-thread programs |
c906108c SS |
2238 | @end menu |
2239 | ||
6d2ebf8b | 2240 | @node Breakpoints |
c906108c SS |
2241 | @section Breakpoints, watchpoints, and catchpoints |
2242 | ||
2243 | @cindex breakpoints | |
2244 | A @dfn{breakpoint} makes your program stop whenever a certain point in | |
2245 | the program is reached. For each breakpoint, you can add conditions to | |
2246 | control in finer detail whether your program stops. You can set | |
2247 | breakpoints with the @code{break} command and its variants (@pxref{Set | |
2248 | Breaks, ,Setting breakpoints}), to specify the place where your program | |
2249 | should stop by line number, function name or exact address in the | |
2250 | program. | |
2251 | ||
2252 | In HP-UX, SunOS 4.x, SVR4, and Alpha OSF/1 configurations, you can set | |
2253 | breakpoints in shared libraries before the executable is run. There is | |
2254 | a minor limitation on HP-UX systems: you must wait until the executable | |
2255 | is run in order to set breakpoints in shared library routines that are | |
2256 | not called directly by the program (for example, routines that are | |
2257 | arguments in a @code{pthread_create} call). | |
2258 | ||
2259 | @cindex watchpoints | |
2260 | @cindex memory tracing | |
2261 | @cindex breakpoint on memory address | |
2262 | @cindex breakpoint on variable modification | |
2263 | A @dfn{watchpoint} is a special breakpoint that stops your program | |
2264 | when the value of an expression changes. You must use a different | |
2265 | command to set watchpoints (@pxref{Set Watchpoints, ,Setting | |
2266 | watchpoints}), but aside from that, you can manage a watchpoint like | |
2267 | any other breakpoint: you enable, disable, and delete both breakpoints | |
2268 | and watchpoints using the same commands. | |
2269 | ||
2270 | You can arrange to have values from your program displayed automatically | |
2271 | whenever @value{GDBN} stops at a breakpoint. @xref{Auto Display,, | |
2272 | Automatic display}. | |
2273 | ||
2274 | @cindex catchpoints | |
2275 | @cindex breakpoint on events | |
2276 | A @dfn{catchpoint} is another special breakpoint that stops your program | |
2277 | when a certain kind of event occurs, such as the throwing of a C++ | |
2278 | exception or the loading of a library. As with watchpoints, you use a | |
2279 | different command to set a catchpoint (@pxref{Set Catchpoints, ,Setting | |
2280 | catchpoints}), but aside from that, you can manage a catchpoint like any | |
2281 | other breakpoint. (To stop when your program receives a signal, use the | |
d4f3574e | 2282 | @code{handle} command; see @ref{Signals, ,Signals}.) |
c906108c SS |
2283 | |
2284 | @cindex breakpoint numbers | |
2285 | @cindex numbers for breakpoints | |
2286 | @value{GDBN} assigns a number to each breakpoint, watchpoint, or | |
2287 | catchpoint when you create it; these numbers are successive integers | |
2288 | starting with one. In many of the commands for controlling various | |
2289 | features of breakpoints you use the breakpoint number to say which | |
2290 | breakpoint you want to change. Each breakpoint may be @dfn{enabled} or | |
2291 | @dfn{disabled}; if disabled, it has no effect on your program until you | |
2292 | enable it again. | |
2293 | ||
c5394b80 JM |
2294 | @cindex breakpoint ranges |
2295 | @cindex ranges of breakpoints | |
2296 | Some @value{GDBN} commands accept a range of breakpoints on which to | |
2297 | operate. A breakpoint range is either a single breakpoint number, like | |
2298 | @samp{5}, or two such numbers, in increasing order, separated by a | |
2299 | hyphen, like @samp{5-7}. When a breakpoint range is given to a command, | |
2300 | all breakpoint in that range are operated on. | |
2301 | ||
c906108c SS |
2302 | @menu |
2303 | * Set Breaks:: Setting breakpoints | |
2304 | * Set Watchpoints:: Setting watchpoints | |
2305 | * Set Catchpoints:: Setting catchpoints | |
2306 | * Delete Breaks:: Deleting breakpoints | |
2307 | * Disabling:: Disabling breakpoints | |
2308 | * Conditions:: Break conditions | |
2309 | * Break Commands:: Breakpoint command lists | |
c906108c | 2310 | * Breakpoint Menus:: Breakpoint menus |
d4f3574e | 2311 | * Error in Breakpoints:: ``Cannot insert breakpoints'' |
c906108c SS |
2312 | @end menu |
2313 | ||
6d2ebf8b | 2314 | @node Set Breaks |
c906108c SS |
2315 | @subsection Setting breakpoints |
2316 | ||
5d161b24 | 2317 | @c FIXME LMB what does GDB do if no code on line of breakpt? |
c906108c SS |
2318 | @c consider in particular declaration with/without initialization. |
2319 | @c | |
2320 | @c FIXME 2 is there stuff on this already? break at fun start, already init? | |
2321 | ||
2322 | @kindex break | |
41afff9a EZ |
2323 | @kindex b @r{(@code{break})} |
2324 | @vindex $bpnum@r{, convenience variable} | |
c906108c SS |
2325 | @cindex latest breakpoint |
2326 | Breakpoints are set with the @code{break} command (abbreviated | |
5d161b24 | 2327 | @code{b}). The debugger convenience variable @samp{$bpnum} records the |
f3b28801 | 2328 | number of the breakpoint you've set most recently; see @ref{Convenience |
c906108c SS |
2329 | Vars,, Convenience variables}, for a discussion of what you can do with |
2330 | convenience variables. | |
2331 | ||
2332 | You have several ways to say where the breakpoint should go. | |
2333 | ||
2334 | @table @code | |
2335 | @item break @var{function} | |
5d161b24 | 2336 | Set a breakpoint at entry to function @var{function}. |
c906108c SS |
2337 | When using source languages that permit overloading of symbols, such as |
2338 | C++, @var{function} may refer to more than one possible place to break. | |
2339 | @xref{Breakpoint Menus,,Breakpoint menus}, for a discussion of that situation. | |
c906108c SS |
2340 | |
2341 | @item break +@var{offset} | |
2342 | @itemx break -@var{offset} | |
2343 | Set a breakpoint some number of lines forward or back from the position | |
d4f3574e | 2344 | at which execution stopped in the currently selected @dfn{stack frame}. |
2df3850c | 2345 | (@xref{Frames, ,Frames}, for a description of stack frames.) |
c906108c SS |
2346 | |
2347 | @item break @var{linenum} | |
2348 | Set a breakpoint at line @var{linenum} in the current source file. | |
d4f3574e SS |
2349 | The current source file is the last file whose source text was printed. |
2350 | The breakpoint will stop your program just before it executes any of the | |
c906108c SS |
2351 | code on that line. |
2352 | ||
2353 | @item break @var{filename}:@var{linenum} | |
2354 | Set a breakpoint at line @var{linenum} in source file @var{filename}. | |
2355 | ||
2356 | @item break @var{filename}:@var{function} | |
2357 | Set a breakpoint at entry to function @var{function} found in file | |
2358 | @var{filename}. Specifying a file name as well as a function name is | |
2359 | superfluous except when multiple files contain similarly named | |
2360 | functions. | |
2361 | ||
2362 | @item break *@var{address} | |
2363 | Set a breakpoint at address @var{address}. You can use this to set | |
2364 | breakpoints in parts of your program which do not have debugging | |
2365 | information or source files. | |
2366 | ||
2367 | @item break | |
2368 | When called without any arguments, @code{break} sets a breakpoint at | |
2369 | the next instruction to be executed in the selected stack frame | |
2370 | (@pxref{Stack, ,Examining the Stack}). In any selected frame but the | |
2371 | innermost, this makes your program stop as soon as control | |
2372 | returns to that frame. This is similar to the effect of a | |
2373 | @code{finish} command in the frame inside the selected frame---except | |
2374 | that @code{finish} does not leave an active breakpoint. If you use | |
2375 | @code{break} without an argument in the innermost frame, @value{GDBN} stops | |
2376 | the next time it reaches the current location; this may be useful | |
2377 | inside loops. | |
2378 | ||
2379 | @value{GDBN} normally ignores breakpoints when it resumes execution, until at | |
2380 | least one instruction has been executed. If it did not do this, you | |
2381 | would be unable to proceed past a breakpoint without first disabling the | |
2382 | breakpoint. This rule applies whether or not the breakpoint already | |
2383 | existed when your program stopped. | |
2384 | ||
2385 | @item break @dots{} if @var{cond} | |
2386 | Set a breakpoint with condition @var{cond}; evaluate the expression | |
2387 | @var{cond} each time the breakpoint is reached, and stop only if the | |
2388 | value is nonzero---that is, if @var{cond} evaluates as true. | |
2389 | @samp{@dots{}} stands for one of the possible arguments described | |
2390 | above (or no argument) specifying where to break. @xref{Conditions, | |
2391 | ,Break conditions}, for more information on breakpoint conditions. | |
2392 | ||
2393 | @kindex tbreak | |
2394 | @item tbreak @var{args} | |
2395 | Set a breakpoint enabled only for one stop. @var{args} are the | |
2396 | same as for the @code{break} command, and the breakpoint is set in the same | |
2397 | way, but the breakpoint is automatically deleted after the first time your | |
2398 | program stops there. @xref{Disabling, ,Disabling breakpoints}. | |
2399 | ||
c906108c SS |
2400 | @kindex hbreak |
2401 | @item hbreak @var{args} | |
d4f3574e SS |
2402 | Set a hardware-assisted breakpoint. @var{args} are the same as for the |
2403 | @code{break} command and the breakpoint is set in the same way, but the | |
c906108c SS |
2404 | breakpoint requires hardware support and some target hardware may not |
2405 | have this support. The main purpose of this is EPROM/ROM code | |
d4f3574e SS |
2406 | debugging, so you can set a breakpoint at an instruction without |
2407 | changing the instruction. This can be used with the new trap-generation | |
2408 | provided by SPARClite DSU and some x86-based targets. These targets | |
2409 | will generate traps when a program accesses some data or instruction | |
2410 | address that is assigned to the debug registers. However the hardware | |
2411 | breakpoint registers can take a limited number of breakpoints. For | |
2412 | example, on the DSU, only two data breakpoints can be set at a time, and | |
2413 | @value{GDBN} will reject this command if more than two are used. Delete | |
2414 | or disable unused hardware breakpoints before setting new ones | |
2415 | (@pxref{Disabling, ,Disabling}). @xref{Conditions, ,Break conditions}. | |
c906108c SS |
2416 | |
2417 | @kindex thbreak | |
2418 | @item thbreak @var{args} | |
2419 | Set a hardware-assisted breakpoint enabled only for one stop. @var{args} | |
2420 | are the same as for the @code{hbreak} command and the breakpoint is set in | |
5d161b24 | 2421 | the same way. However, like the @code{tbreak} command, |
c906108c SS |
2422 | the breakpoint is automatically deleted after the |
2423 | first time your program stops there. Also, like the @code{hbreak} | |
5d161b24 DB |
2424 | command, the breakpoint requires hardware support and some target hardware |
2425 | may not have this support. @xref{Disabling, ,Disabling breakpoints}. | |
d4f3574e | 2426 | See also @ref{Conditions, ,Break conditions}. |
c906108c SS |
2427 | |
2428 | @kindex rbreak | |
2429 | @cindex regular expression | |
2430 | @item rbreak @var{regex} | |
c906108c | 2431 | Set breakpoints on all functions matching the regular expression |
11cf8741 JM |
2432 | @var{regex}. This command sets an unconditional breakpoint on all |
2433 | matches, printing a list of all breakpoints it set. Once these | |
2434 | breakpoints are set, they are treated just like the breakpoints set with | |
2435 | the @code{break} command. You can delete them, disable them, or make | |
2436 | them conditional the same way as any other breakpoint. | |
2437 | ||
2438 | The syntax of the regular expression is the standard one used with tools | |
2439 | like @file{grep}. Note that this is different from the syntax used by | |
2440 | shells, so for instance @code{foo*} matches all functions that include | |
2441 | an @code{fo} followed by zero or more @code{o}s. There is an implicit | |
2442 | @code{.*} leading and trailing the regular expression you supply, so to | |
2443 | match only functions that begin with @code{foo}, use @code{^foo}. | |
c906108c | 2444 | |
c906108c SS |
2445 | When debugging C++ programs, @code{rbreak} is useful for setting |
2446 | breakpoints on overloaded functions that are not members of any special | |
2447 | classes. | |
c906108c SS |
2448 | |
2449 | @kindex info breakpoints | |
2450 | @cindex @code{$_} and @code{info breakpoints} | |
2451 | @item info breakpoints @r{[}@var{n}@r{]} | |
2452 | @itemx info break @r{[}@var{n}@r{]} | |
2453 | @itemx info watchpoints @r{[}@var{n}@r{]} | |
2454 | Print a table of all breakpoints, watchpoints, and catchpoints set and | |
2455 | not deleted, with the following columns for each breakpoint: | |
2456 | ||
2457 | @table @emph | |
2458 | @item Breakpoint Numbers | |
2459 | @item Type | |
2460 | Breakpoint, watchpoint, or catchpoint. | |
2461 | @item Disposition | |
2462 | Whether the breakpoint is marked to be disabled or deleted when hit. | |
2463 | @item Enabled or Disabled | |
2464 | Enabled breakpoints are marked with @samp{y}. @samp{n} marks breakpoints | |
2465 | that are not enabled. | |
2466 | @item Address | |
2df3850c | 2467 | Where the breakpoint is in your program, as a memory address. |
c906108c SS |
2468 | @item What |
2469 | Where the breakpoint is in the source for your program, as a file and | |
2470 | line number. | |
2471 | @end table | |
2472 | ||
2473 | @noindent | |
2474 | If a breakpoint is conditional, @code{info break} shows the condition on | |
2475 | the line following the affected breakpoint; breakpoint commands, if any, | |
2476 | are listed after that. | |
2477 | ||
2478 | @noindent | |
2479 | @code{info break} with a breakpoint | |
2480 | number @var{n} as argument lists only that breakpoint. The | |
2481 | convenience variable @code{$_} and the default examining-address for | |
2482 | the @code{x} command are set to the address of the last breakpoint | |
5d161b24 | 2483 | listed (@pxref{Memory, ,Examining memory}). |
c906108c SS |
2484 | |
2485 | @noindent | |
2486 | @code{info break} displays a count of the number of times the breakpoint | |
2487 | has been hit. This is especially useful in conjunction with the | |
2488 | @code{ignore} command. You can ignore a large number of breakpoint | |
2489 | hits, look at the breakpoint info to see how many times the breakpoint | |
2490 | was hit, and then run again, ignoring one less than that number. This | |
2491 | will get you quickly to the last hit of that breakpoint. | |
2492 | @end table | |
2493 | ||
2494 | @value{GDBN} allows you to set any number of breakpoints at the same place in | |
2495 | your program. There is nothing silly or meaningless about this. When | |
2496 | the breakpoints are conditional, this is even useful | |
2497 | (@pxref{Conditions, ,Break conditions}). | |
2498 | ||
2499 | @cindex negative breakpoint numbers | |
2500 | @cindex internal @value{GDBN} breakpoints | |
2501 | @value{GDBN} itself sometimes sets breakpoints in your program for special | |
2502 | purposes, such as proper handling of @code{longjmp} (in C programs). | |
2503 | These internal breakpoints are assigned negative numbers, starting with | |
2504 | @code{-1}; @samp{info breakpoints} does not display them. | |
2505 | ||
2506 | You can see these breakpoints with the @value{GDBN} maintenance command | |
2507 | @samp{maint info breakpoints}. | |
2508 | ||
2509 | @table @code | |
2510 | @kindex maint info breakpoints | |
2511 | @item maint info breakpoints | |
2512 | Using the same format as @samp{info breakpoints}, display both the | |
2513 | breakpoints you've set explicitly, and those @value{GDBN} is using for | |
2514 | internal purposes. Internal breakpoints are shown with negative | |
2515 | breakpoint numbers. The type column identifies what kind of breakpoint | |
2516 | is shown: | |
2517 | ||
2518 | @table @code | |
2519 | @item breakpoint | |
2520 | Normal, explicitly set breakpoint. | |
2521 | ||
2522 | @item watchpoint | |
2523 | Normal, explicitly set watchpoint. | |
2524 | ||
2525 | @item longjmp | |
2526 | Internal breakpoint, used to handle correctly stepping through | |
2527 | @code{longjmp} calls. | |
2528 | ||
2529 | @item longjmp resume | |
2530 | Internal breakpoint at the target of a @code{longjmp}. | |
2531 | ||
2532 | @item until | |
2533 | Temporary internal breakpoint used by the @value{GDBN} @code{until} command. | |
2534 | ||
2535 | @item finish | |
2536 | Temporary internal breakpoint used by the @value{GDBN} @code{finish} command. | |
2537 | ||
c906108c SS |
2538 | @item shlib events |
2539 | Shared library events. | |
53a5351d | 2540 | |
c906108c | 2541 | @end table |
53a5351d | 2542 | |
c906108c SS |
2543 | @end table |
2544 | ||
2545 | ||
6d2ebf8b | 2546 | @node Set Watchpoints |
c906108c SS |
2547 | @subsection Setting watchpoints |
2548 | ||
2549 | @cindex setting watchpoints | |
2550 | @cindex software watchpoints | |
2551 | @cindex hardware watchpoints | |
2552 | You can use a watchpoint to stop execution whenever the value of an | |
2553 | expression changes, without having to predict a particular place where | |
2554 | this may happen. | |
2555 | ||
2556 | Depending on your system, watchpoints may be implemented in software or | |
2df3850c | 2557 | hardware. @value{GDBN} does software watchpointing by single-stepping your |
c906108c SS |
2558 | program and testing the variable's value each time, which is hundreds of |
2559 | times slower than normal execution. (But this may still be worth it, to | |
2560 | catch errors where you have no clue what part of your program is the | |
2561 | culprit.) | |
2562 | ||
d4f3574e | 2563 | On some systems, such as HP-UX, Linux and some other x86-based targets, |
2df3850c | 2564 | @value{GDBN} includes support for |
c906108c SS |
2565 | hardware watchpoints, which do not slow down the running of your |
2566 | program. | |
2567 | ||
2568 | @table @code | |
2569 | @kindex watch | |
2570 | @item watch @var{expr} | |
2571 | Set a watchpoint for an expression. @value{GDBN} will break when @var{expr} | |
2572 | is written into by the program and its value changes. | |
2573 | ||
2574 | @kindex rwatch | |
2575 | @item rwatch @var{expr} | |
2576 | Set a watchpoint that will break when watch @var{expr} is read by the program. | |
c906108c SS |
2577 | |
2578 | @kindex awatch | |
2579 | @item awatch @var{expr} | |
2df3850c | 2580 | Set a watchpoint that will break when @var{expr} is either read or written into |
7be570e7 | 2581 | by the program. |
c906108c SS |
2582 | |
2583 | @kindex info watchpoints | |
2584 | @item info watchpoints | |
2585 | This command prints a list of watchpoints, breakpoints, and catchpoints; | |
2586 | it is the same as @code{info break}. | |
2587 | @end table | |
2588 | ||
2589 | @value{GDBN} sets a @dfn{hardware watchpoint} if possible. Hardware | |
2590 | watchpoints execute very quickly, and the debugger reports a change in | |
2591 | value at the exact instruction where the change occurs. If @value{GDBN} | |
2592 | cannot set a hardware watchpoint, it sets a software watchpoint, which | |
2593 | executes more slowly and reports the change in value at the next | |
2594 | statement, not the instruction, after the change occurs. | |
2595 | ||
2596 | When you issue the @code{watch} command, @value{GDBN} reports | |
2597 | ||
2598 | @example | |
2599 | Hardware watchpoint @var{num}: @var{expr} | |
2600 | @end example | |
2601 | ||
2602 | @noindent | |
2603 | if it was able to set a hardware watchpoint. | |
2604 | ||
7be570e7 JM |
2605 | Currently, the @code{awatch} and @code{rwatch} commands can only set |
2606 | hardware watchpoints, because accesses to data that don't change the | |
2607 | value of the watched expression cannot be detected without examining | |
2608 | every instruction as it is being executed, and @value{GDBN} does not do | |
2609 | that currently. If @value{GDBN} finds that it is unable to set a | |
2610 | hardware breakpoint with the @code{awatch} or @code{rwatch} command, it | |
2611 | will print a message like this: | |
2612 | ||
2613 | @smallexample | |
2614 | Expression cannot be implemented with read/access watchpoint. | |
2615 | @end smallexample | |
2616 | ||
2617 | Sometimes, @value{GDBN} cannot set a hardware watchpoint because the | |
2618 | data type of the watched expression is wider than what a hardware | |
2619 | watchpoint on the target machine can handle. For example, some systems | |
2620 | can only watch regions that are up to 4 bytes wide; on such systems you | |
2621 | cannot set hardware watchpoints for an expression that yields a | |
2622 | double-precision floating-point number (which is typically 8 bytes | |
2623 | wide). As a work-around, it might be possible to break the large region | |
2624 | into a series of smaller ones and watch them with separate watchpoints. | |
2625 | ||
2626 | If you set too many hardware watchpoints, @value{GDBN} might be unable | |
2627 | to insert all of them when you resume the execution of your program. | |
2628 | Since the precise number of active watchpoints is unknown until such | |
2629 | time as the program is about to be resumed, @value{GDBN} might not be | |
2630 | able to warn you about this when you set the watchpoints, and the | |
2631 | warning will be printed only when the program is resumed: | |
2632 | ||
2633 | @smallexample | |
2634 | Hardware watchpoint @var{num}: Could not insert watchpoint | |
2635 | @end smallexample | |
2636 | ||
2637 | @noindent | |
2638 | If this happens, delete or disable some of the watchpoints. | |
2639 | ||
2640 | The SPARClite DSU will generate traps when a program accesses some data | |
2641 | or instruction address that is assigned to the debug registers. For the | |
2642 | data addresses, DSU facilitates the @code{watch} command. However the | |
2643 | hardware breakpoint registers can only take two data watchpoints, and | |
2644 | both watchpoints must be the same kind. For example, you can set two | |
2645 | watchpoints with @code{watch} commands, two with @code{rwatch} commands, | |
2646 | @strong{or} two with @code{awatch} commands, but you cannot set one | |
2647 | watchpoint with one command and the other with a different command. | |
c906108c SS |
2648 | @value{GDBN} will reject the command if you try to mix watchpoints. |
2649 | Delete or disable unused watchpoint commands before setting new ones. | |
2650 | ||
2651 | If you call a function interactively using @code{print} or @code{call}, | |
2df3850c | 2652 | any watchpoints you have set will be inactive until @value{GDBN} reaches another |
c906108c SS |
2653 | kind of breakpoint or the call completes. |
2654 | ||
7be570e7 JM |
2655 | @value{GDBN} automatically deletes watchpoints that watch local |
2656 | (automatic) variables, or expressions that involve such variables, when | |
2657 | they go out of scope, that is, when the execution leaves the block in | |
2658 | which these variables were defined. In particular, when the program | |
2659 | being debugged terminates, @emph{all} local variables go out of scope, | |
2660 | and so only watchpoints that watch global variables remain set. If you | |
2661 | rerun the program, you will need to set all such watchpoints again. One | |
2662 | way of doing that would be to set a code breakpoint at the entry to the | |
2663 | @code{main} function and when it breaks, set all the watchpoints. | |
2664 | ||
c906108c SS |
2665 | @quotation |
2666 | @cindex watchpoints and threads | |
2667 | @cindex threads and watchpoints | |
c906108c SS |
2668 | @emph{Warning:} In multi-thread programs, watchpoints have only limited |
2669 | usefulness. With the current watchpoint implementation, @value{GDBN} | |
2670 | can only watch the value of an expression @emph{in a single thread}. If | |
2671 | you are confident that the expression can only change due to the current | |
2672 | thread's activity (and if you are also confident that no other thread | |
2673 | can become current), then you can use watchpoints as usual. However, | |
2674 | @value{GDBN} may not notice when a non-current thread's activity changes | |
2675 | the expression. | |
53a5351d | 2676 | |
d4f3574e | 2677 | @c FIXME: this is almost identical to the previous paragraph. |
53a5351d JM |
2678 | @emph{HP-UX Warning:} In multi-thread programs, software watchpoints |
2679 | have only limited usefulness. If @value{GDBN} creates a software | |
2680 | watchpoint, it can only watch the value of an expression @emph{in a | |
2681 | single thread}. If you are confident that the expression can only | |
2682 | change due to the current thread's activity (and if you are also | |
2683 | confident that no other thread can become current), then you can use | |
2684 | software watchpoints as usual. However, @value{GDBN} may not notice | |
2685 | when a non-current thread's activity changes the expression. (Hardware | |
2686 | watchpoints, in contrast, watch an expression in all threads.) | |
c906108c | 2687 | @end quotation |
c906108c | 2688 | |
6d2ebf8b | 2689 | @node Set Catchpoints |
c906108c | 2690 | @subsection Setting catchpoints |
d4f3574e | 2691 | @cindex catchpoints, setting |
c906108c SS |
2692 | @cindex exception handlers |
2693 | @cindex event handling | |
2694 | ||
2695 | You can use @dfn{catchpoints} to cause the debugger to stop for certain | |
2696 | kinds of program events, such as C++ exceptions or the loading of a | |
2697 | shared library. Use the @code{catch} command to set a catchpoint. | |
2698 | ||
2699 | @table @code | |
2700 | @kindex catch | |
2701 | @item catch @var{event} | |
2702 | Stop when @var{event} occurs. @var{event} can be any of the following: | |
2703 | @table @code | |
2704 | @item throw | |
2705 | @kindex catch throw | |
2706 | The throwing of a C++ exception. | |
2707 | ||
2708 | @item catch | |
2709 | @kindex catch catch | |
2710 | The catching of a C++ exception. | |
2711 | ||
2712 | @item exec | |
2713 | @kindex catch exec | |
2714 | A call to @code{exec}. This is currently only available for HP-UX. | |
2715 | ||
2716 | @item fork | |
2717 | @kindex catch fork | |
2718 | A call to @code{fork}. This is currently only available for HP-UX. | |
2719 | ||
2720 | @item vfork | |
2721 | @kindex catch vfork | |
2722 | A call to @code{vfork}. This is currently only available for HP-UX. | |
2723 | ||
2724 | @item load | |
2725 | @itemx load @var{libname} | |
2726 | @kindex catch load | |
2727 | The dynamic loading of any shared library, or the loading of the library | |
2728 | @var{libname}. This is currently only available for HP-UX. | |
2729 | ||
2730 | @item unload | |
2731 | @itemx unload @var{libname} | |
2732 | @kindex catch unload | |
2733 | The unloading of any dynamically loaded shared library, or the unloading | |
2734 | of the library @var{libname}. This is currently only available for HP-UX. | |
2735 | @end table | |
2736 | ||
2737 | @item tcatch @var{event} | |
2738 | Set a catchpoint that is enabled only for one stop. The catchpoint is | |
2739 | automatically deleted after the first time the event is caught. | |
2740 | ||
2741 | @end table | |
2742 | ||
2743 | Use the @code{info break} command to list the current catchpoints. | |
2744 | ||
2745 | There are currently some limitations to C++ exception handling | |
2746 | (@code{catch throw} and @code{catch catch}) in @value{GDBN}: | |
2747 | ||
2748 | @itemize @bullet | |
2749 | @item | |
2750 | If you call a function interactively, @value{GDBN} normally returns | |
2751 | control to you when the function has finished executing. If the call | |
2752 | raises an exception, however, the call may bypass the mechanism that | |
2753 | returns control to you and cause your program either to abort or to | |
2754 | simply continue running until it hits a breakpoint, catches a signal | |
2755 | that @value{GDBN} is listening for, or exits. This is the case even if | |
2756 | you set a catchpoint for the exception; catchpoints on exceptions are | |
2757 | disabled within interactive calls. | |
2758 | ||
2759 | @item | |
2760 | You cannot raise an exception interactively. | |
2761 | ||
2762 | @item | |
2763 | You cannot install an exception handler interactively. | |
2764 | @end itemize | |
2765 | ||
2766 | @cindex raise exceptions | |
2767 | Sometimes @code{catch} is not the best way to debug exception handling: | |
2768 | if you need to know exactly where an exception is raised, it is better to | |
2769 | stop @emph{before} the exception handler is called, since that way you | |
2770 | can see the stack before any unwinding takes place. If you set a | |
2771 | breakpoint in an exception handler instead, it may not be easy to find | |
2772 | out where the exception was raised. | |
2773 | ||
2774 | To stop just before an exception handler is called, you need some | |
2775 | knowledge of the implementation. In the case of @sc{gnu} C++, exceptions are | |
2776 | raised by calling a library function named @code{__raise_exception} | |
2777 | which has the following ANSI C interface: | |
2778 | ||
2779 | @example | |
2780 | /* @var{addr} is where the exception identifier is stored. | |
d4f3574e SS |
2781 | @var{id} is the exception identifier. */ |
2782 | void __raise_exception (void **addr, void *id); | |
c906108c SS |
2783 | @end example |
2784 | ||
2785 | @noindent | |
2786 | To make the debugger catch all exceptions before any stack | |
2787 | unwinding takes place, set a breakpoint on @code{__raise_exception} | |
2788 | (@pxref{Breakpoints, ,Breakpoints; watchpoints; and exceptions}). | |
2789 | ||
2790 | With a conditional breakpoint (@pxref{Conditions, ,Break conditions}) | |
2791 | that depends on the value of @var{id}, you can stop your program when | |
2792 | a specific exception is raised. You can use multiple conditional | |
2793 | breakpoints to stop your program when any of a number of exceptions are | |
2794 | raised. | |
2795 | ||
2796 | ||
6d2ebf8b | 2797 | @node Delete Breaks |
c906108c SS |
2798 | @subsection Deleting breakpoints |
2799 | ||
2800 | @cindex clearing breakpoints, watchpoints, catchpoints | |
2801 | @cindex deleting breakpoints, watchpoints, catchpoints | |
2802 | It is often necessary to eliminate a breakpoint, watchpoint, or | |
2803 | catchpoint once it has done its job and you no longer want your program | |
2804 | to stop there. This is called @dfn{deleting} the breakpoint. A | |
2805 | breakpoint that has been deleted no longer exists; it is forgotten. | |
2806 | ||
2807 | With the @code{clear} command you can delete breakpoints according to | |
2808 | where they are in your program. With the @code{delete} command you can | |
2809 | delete individual breakpoints, watchpoints, or catchpoints by specifying | |
2810 | their breakpoint numbers. | |
2811 | ||
2812 | It is not necessary to delete a breakpoint to proceed past it. @value{GDBN} | |
2813 | automatically ignores breakpoints on the first instruction to be executed | |
2814 | when you continue execution without changing the execution address. | |
2815 | ||
2816 | @table @code | |
2817 | @kindex clear | |
2818 | @item clear | |
2819 | Delete any breakpoints at the next instruction to be executed in the | |
2820 | selected stack frame (@pxref{Selection, ,Selecting a frame}). When | |
2821 | the innermost frame is selected, this is a good way to delete a | |
2822 | breakpoint where your program just stopped. | |
2823 | ||
2824 | @item clear @var{function} | |
2825 | @itemx clear @var{filename}:@var{function} | |
2826 | Delete any breakpoints set at entry to the function @var{function}. | |
2827 | ||
2828 | @item clear @var{linenum} | |
2829 | @itemx clear @var{filename}:@var{linenum} | |
2830 | Delete any breakpoints set at or within the code of the specified line. | |
2831 | ||
2832 | @cindex delete breakpoints | |
2833 | @kindex delete | |
41afff9a | 2834 | @kindex d @r{(@code{delete})} |
c5394b80 JM |
2835 | @item delete @r{[}breakpoints@r{]} @r{[}@var{range}@dots{}@r{]} |
2836 | Delete the breakpoints, watchpoints, or catchpoints of the breakpoint | |
2837 | ranges specified as arguments. If no argument is specified, delete all | |
c906108c SS |
2838 | breakpoints (@value{GDBN} asks confirmation, unless you have @code{set |
2839 | confirm off}). You can abbreviate this command as @code{d}. | |
2840 | @end table | |
2841 | ||
6d2ebf8b | 2842 | @node Disabling |
c906108c SS |
2843 | @subsection Disabling breakpoints |
2844 | ||
2845 | @kindex disable breakpoints | |
2846 | @kindex enable breakpoints | |
2847 | Rather than deleting a breakpoint, watchpoint, or catchpoint, you might | |
2848 | prefer to @dfn{disable} it. This makes the breakpoint inoperative as if | |
2849 | it had been deleted, but remembers the information on the breakpoint so | |
2850 | that you can @dfn{enable} it again later. | |
2851 | ||
2852 | You disable and enable breakpoints, watchpoints, and catchpoints with | |
2853 | the @code{enable} and @code{disable} commands, optionally specifying one | |
2854 | or more breakpoint numbers as arguments. Use @code{info break} or | |
2855 | @code{info watch} to print a list of breakpoints, watchpoints, and | |
2856 | catchpoints if you do not know which numbers to use. | |
2857 | ||
2858 | A breakpoint, watchpoint, or catchpoint can have any of four different | |
2859 | states of enablement: | |
2860 | ||
2861 | @itemize @bullet | |
2862 | @item | |
2863 | Enabled. The breakpoint stops your program. A breakpoint set | |
2864 | with the @code{break} command starts out in this state. | |
2865 | @item | |
2866 | Disabled. The breakpoint has no effect on your program. | |
2867 | @item | |
2868 | Enabled once. The breakpoint stops your program, but then becomes | |
d4f3574e | 2869 | disabled. |
c906108c SS |
2870 | @item |
2871 | Enabled for deletion. The breakpoint stops your program, but | |
d4f3574e SS |
2872 | immediately after it does so it is deleted permanently. A breakpoint |
2873 | set with the @code{tbreak} command starts out in this state. | |
c906108c SS |
2874 | @end itemize |
2875 | ||
2876 | You can use the following commands to enable or disable breakpoints, | |
2877 | watchpoints, and catchpoints: | |
2878 | ||
2879 | @table @code | |
2880 | @kindex disable breakpoints | |
2881 | @kindex disable | |
41afff9a | 2882 | @kindex dis @r{(@code{disable})} |
c5394b80 | 2883 | @item disable @r{[}breakpoints@r{]} @r{[}@var{range}@dots{}@r{]} |
c906108c SS |
2884 | Disable the specified breakpoints---or all breakpoints, if none are |
2885 | listed. A disabled breakpoint has no effect but is not forgotten. All | |
2886 | options such as ignore-counts, conditions and commands are remembered in | |
2887 | case the breakpoint is enabled again later. You may abbreviate | |
2888 | @code{disable} as @code{dis}. | |
2889 | ||
2890 | @kindex enable breakpoints | |
2891 | @kindex enable | |
c5394b80 | 2892 | @item enable @r{[}breakpoints@r{]} @r{[}@var{range}@dots{}@r{]} |
c906108c SS |
2893 | Enable the specified breakpoints (or all defined breakpoints). They |
2894 | become effective once again in stopping your program. | |
2895 | ||
c5394b80 | 2896 | @item enable @r{[}breakpoints@r{]} once @var{range}@dots{} |
c906108c SS |
2897 | Enable the specified breakpoints temporarily. @value{GDBN} disables any |
2898 | of these breakpoints immediately after stopping your program. | |
2899 | ||
c5394b80 | 2900 | @item enable @r{[}breakpoints@r{]} delete @var{range}@dots{} |
c906108c SS |
2901 | Enable the specified breakpoints to work once, then die. @value{GDBN} |
2902 | deletes any of these breakpoints as soon as your program stops there. | |
2903 | @end table | |
2904 | ||
d4f3574e SS |
2905 | @c FIXME: I think the following ``Except for [...] @code{tbreak}'' is |
2906 | @c confusing: tbreak is also initially enabled. | |
c906108c SS |
2907 | Except for a breakpoint set with @code{tbreak} (@pxref{Set Breaks, |
2908 | ,Setting breakpoints}), breakpoints that you set are initially enabled; | |
2909 | subsequently, they become disabled or enabled only when you use one of | |
2910 | the commands above. (The command @code{until} can set and delete a | |
2911 | breakpoint of its own, but it does not change the state of your other | |
2912 | breakpoints; see @ref{Continuing and Stepping, ,Continuing and | |
2913 | stepping}.) | |
2914 | ||
6d2ebf8b | 2915 | @node Conditions |
c906108c SS |
2916 | @subsection Break conditions |
2917 | @cindex conditional breakpoints | |
2918 | @cindex breakpoint conditions | |
2919 | ||
2920 | @c FIXME what is scope of break condition expr? Context where wanted? | |
5d161b24 | 2921 | @c in particular for a watchpoint? |
c906108c SS |
2922 | The simplest sort of breakpoint breaks every time your program reaches a |
2923 | specified place. You can also specify a @dfn{condition} for a | |
2924 | breakpoint. A condition is just a Boolean expression in your | |
2925 | programming language (@pxref{Expressions, ,Expressions}). A breakpoint with | |
2926 | a condition evaluates the expression each time your program reaches it, | |
2927 | and your program stops only if the condition is @emph{true}. | |
2928 | ||
2929 | This is the converse of using assertions for program validation; in that | |
2930 | situation, you want to stop when the assertion is violated---that is, | |
2931 | when the condition is false. In C, if you want to test an assertion expressed | |
2932 | by the condition @var{assert}, you should set the condition | |
2933 | @samp{! @var{assert}} on the appropriate breakpoint. | |
2934 | ||
2935 | Conditions are also accepted for watchpoints; you may not need them, | |
2936 | since a watchpoint is inspecting the value of an expression anyhow---but | |
2937 | it might be simpler, say, to just set a watchpoint on a variable name, | |
2938 | and specify a condition that tests whether the new value is an interesting | |
2939 | one. | |
2940 | ||
2941 | Break conditions can have side effects, and may even call functions in | |
2942 | your program. This can be useful, for example, to activate functions | |
2943 | that log program progress, or to use your own print functions to | |
2944 | format special data structures. The effects are completely predictable | |
2945 | unless there is another enabled breakpoint at the same address. (In | |
2946 | that case, @value{GDBN} might see the other breakpoint first and stop your | |
2947 | program without checking the condition of this one.) Note that | |
d4f3574e SS |
2948 | breakpoint commands are usually more convenient and flexible than break |
2949 | conditions for the | |
c906108c SS |
2950 | purpose of performing side effects when a breakpoint is reached |
2951 | (@pxref{Break Commands, ,Breakpoint command lists}). | |
2952 | ||
2953 | Break conditions can be specified when a breakpoint is set, by using | |
2954 | @samp{if} in the arguments to the @code{break} command. @xref{Set | |
2955 | Breaks, ,Setting breakpoints}. They can also be changed at any time | |
2956 | with the @code{condition} command. | |
53a5351d | 2957 | |
c906108c SS |
2958 | You can also use the @code{if} keyword with the @code{watch} command. |
2959 | The @code{catch} command does not recognize the @code{if} keyword; | |
2960 | @code{condition} is the only way to impose a further condition on a | |
2961 | catchpoint. | |
c906108c SS |
2962 | |
2963 | @table @code | |
2964 | @kindex condition | |
2965 | @item condition @var{bnum} @var{expression} | |
2966 | Specify @var{expression} as the break condition for breakpoint, | |
2967 | watchpoint, or catchpoint number @var{bnum}. After you set a condition, | |
2968 | breakpoint @var{bnum} stops your program only if the value of | |
2969 | @var{expression} is true (nonzero, in C). When you use | |
2970 | @code{condition}, @value{GDBN} checks @var{expression} immediately for | |
2971 | syntactic correctness, and to determine whether symbols in it have | |
d4f3574e SS |
2972 | referents in the context of your breakpoint. If @var{expression} uses |
2973 | symbols not referenced in the context of the breakpoint, @value{GDBN} | |
2974 | prints an error message: | |
2975 | ||
2976 | @example | |
2977 | No symbol "foo" in current context. | |
2978 | @end example | |
2979 | ||
2980 | @noindent | |
c906108c SS |
2981 | @value{GDBN} does |
2982 | not actually evaluate @var{expression} at the time the @code{condition} | |
d4f3574e SS |
2983 | command (or a command that sets a breakpoint with a condition, like |
2984 | @code{break if @dots{}}) is given, however. @xref{Expressions, ,Expressions}. | |
c906108c SS |
2985 | |
2986 | @item condition @var{bnum} | |
2987 | Remove the condition from breakpoint number @var{bnum}. It becomes | |
2988 | an ordinary unconditional breakpoint. | |
2989 | @end table | |
2990 | ||
2991 | @cindex ignore count (of breakpoint) | |
2992 | A special case of a breakpoint condition is to stop only when the | |
2993 | breakpoint has been reached a certain number of times. This is so | |
2994 | useful that there is a special way to do it, using the @dfn{ignore | |
2995 | count} of the breakpoint. Every breakpoint has an ignore count, which | |
2996 | is an integer. Most of the time, the ignore count is zero, and | |
2997 | therefore has no effect. But if your program reaches a breakpoint whose | |
2998 | ignore count is positive, then instead of stopping, it just decrements | |
2999 | the ignore count by one and continues. As a result, if the ignore count | |
3000 | value is @var{n}, the breakpoint does not stop the next @var{n} times | |
3001 | your program reaches it. | |
3002 | ||
3003 | @table @code | |
3004 | @kindex ignore | |
3005 | @item ignore @var{bnum} @var{count} | |
3006 | Set the ignore count of breakpoint number @var{bnum} to @var{count}. | |
3007 | The next @var{count} times the breakpoint is reached, your program's | |
3008 | execution does not stop; other than to decrement the ignore count, @value{GDBN} | |
3009 | takes no action. | |
3010 | ||
3011 | To make the breakpoint stop the next time it is reached, specify | |
3012 | a count of zero. | |
3013 | ||
3014 | When you use @code{continue} to resume execution of your program from a | |
3015 | breakpoint, you can specify an ignore count directly as an argument to | |
3016 | @code{continue}, rather than using @code{ignore}. @xref{Continuing and | |
3017 | Stepping,,Continuing and stepping}. | |
3018 | ||
3019 | If a breakpoint has a positive ignore count and a condition, the | |
3020 | condition is not checked. Once the ignore count reaches zero, | |
3021 | @value{GDBN} resumes checking the condition. | |
3022 | ||
3023 | You could achieve the effect of the ignore count with a condition such | |
3024 | as @w{@samp{$foo-- <= 0}} using a debugger convenience variable that | |
3025 | is decremented each time. @xref{Convenience Vars, ,Convenience | |
3026 | variables}. | |
3027 | @end table | |
3028 | ||
3029 | Ignore counts apply to breakpoints, watchpoints, and catchpoints. | |
3030 | ||
3031 | ||
6d2ebf8b | 3032 | @node Break Commands |
c906108c SS |
3033 | @subsection Breakpoint command lists |
3034 | ||
3035 | @cindex breakpoint commands | |
3036 | You can give any breakpoint (or watchpoint or catchpoint) a series of | |
3037 | commands to execute when your program stops due to that breakpoint. For | |
3038 | example, you might want to print the values of certain expressions, or | |
3039 | enable other breakpoints. | |
3040 | ||
3041 | @table @code | |
3042 | @kindex commands | |
3043 | @kindex end | |
3044 | @item commands @r{[}@var{bnum}@r{]} | |
3045 | @itemx @dots{} @var{command-list} @dots{} | |
3046 | @itemx end | |
3047 | Specify a list of commands for breakpoint number @var{bnum}. The commands | |
3048 | themselves appear on the following lines. Type a line containing just | |
3049 | @code{end} to terminate the commands. | |
3050 | ||
3051 | To remove all commands from a breakpoint, type @code{commands} and | |
3052 | follow it immediately with @code{end}; that is, give no commands. | |
3053 | ||
3054 | With no @var{bnum} argument, @code{commands} refers to the last | |
3055 | breakpoint, watchpoint, or catchpoint set (not to the breakpoint most | |
3056 | recently encountered). | |
3057 | @end table | |
3058 | ||
3059 | Pressing @key{RET} as a means of repeating the last @value{GDBN} command is | |
3060 | disabled within a @var{command-list}. | |
3061 | ||
3062 | You can use breakpoint commands to start your program up again. Simply | |
3063 | use the @code{continue} command, or @code{step}, or any other command | |
3064 | that resumes execution. | |
3065 | ||
3066 | Any other commands in the command list, after a command that resumes | |
3067 | execution, are ignored. This is because any time you resume execution | |
3068 | (even with a simple @code{next} or @code{step}), you may encounter | |
3069 | another breakpoint---which could have its own command list, leading to | |
3070 | ambiguities about which list to execute. | |
3071 | ||
3072 | @kindex silent | |
3073 | If the first command you specify in a command list is @code{silent}, the | |
3074 | usual message about stopping at a breakpoint is not printed. This may | |
3075 | be desirable for breakpoints that are to print a specific message and | |
3076 | then continue. If none of the remaining commands print anything, you | |
3077 | see no sign that the breakpoint was reached. @code{silent} is | |
3078 | meaningful only at the beginning of a breakpoint command list. | |
3079 | ||
3080 | The commands @code{echo}, @code{output}, and @code{printf} allow you to | |
3081 | print precisely controlled output, and are often useful in silent | |
3082 | breakpoints. @xref{Output, ,Commands for controlled output}. | |
3083 | ||
3084 | For example, here is how you could use breakpoint commands to print the | |
3085 | value of @code{x} at entry to @code{foo} whenever @code{x} is positive. | |
3086 | ||
3087 | @example | |
3088 | break foo if x>0 | |
3089 | commands | |
3090 | silent | |
3091 | printf "x is %d\n",x | |
3092 | cont | |
3093 | end | |
3094 | @end example | |
3095 | ||
3096 | One application for breakpoint commands is to compensate for one bug so | |
3097 | you can test for another. Put a breakpoint just after the erroneous line | |
3098 | of code, give it a condition to detect the case in which something | |
3099 | erroneous has been done, and give it commands to assign correct values | |
3100 | to any variables that need them. End with the @code{continue} command | |
3101 | so that your program does not stop, and start with the @code{silent} | |
3102 | command so that no output is produced. Here is an example: | |
3103 | ||
3104 | @example | |
3105 | break 403 | |
3106 | commands | |
3107 | silent | |
3108 | set x = y + 4 | |
3109 | cont | |
3110 | end | |
3111 | @end example | |
3112 | ||
6d2ebf8b | 3113 | @node Breakpoint Menus |
c906108c SS |
3114 | @subsection Breakpoint menus |
3115 | @cindex overloading | |
3116 | @cindex symbol overloading | |
3117 | ||
3118 | Some programming languages (notably C++) permit a single function name | |
3119 | to be defined several times, for application in different contexts. | |
3120 | This is called @dfn{overloading}. When a function name is overloaded, | |
3121 | @samp{break @var{function}} is not enough to tell @value{GDBN} where you want | |
3122 | a breakpoint. If you realize this is a problem, you can use | |
3123 | something like @samp{break @var{function}(@var{types})} to specify which | |
3124 | particular version of the function you want. Otherwise, @value{GDBN} offers | |
3125 | you a menu of numbered choices for different possible breakpoints, and | |
3126 | waits for your selection with the prompt @samp{>}. The first two | |
3127 | options are always @samp{[0] cancel} and @samp{[1] all}. Typing @kbd{1} | |
3128 | sets a breakpoint at each definition of @var{function}, and typing | |
3129 | @kbd{0} aborts the @code{break} command without setting any new | |
3130 | breakpoints. | |
3131 | ||
3132 | For example, the following session excerpt shows an attempt to set a | |
3133 | breakpoint at the overloaded symbol @code{String::after}. | |
3134 | We choose three particular definitions of that function name: | |
3135 | ||
3136 | @c FIXME! This is likely to change to show arg type lists, at least | |
3137 | @smallexample | |
3138 | @group | |
3139 | (@value{GDBP}) b String::after | |
3140 | [0] cancel | |
3141 | [1] all | |
3142 | [2] file:String.cc; line number:867 | |
3143 | [3] file:String.cc; line number:860 | |
3144 | [4] file:String.cc; line number:875 | |
3145 | [5] file:String.cc; line number:853 | |
3146 | [6] file:String.cc; line number:846 | |
3147 | [7] file:String.cc; line number:735 | |
3148 | > 2 4 6 | |
3149 | Breakpoint 1 at 0xb26c: file String.cc, line 867. | |
3150 | Breakpoint 2 at 0xb344: file String.cc, line 875. | |
3151 | Breakpoint 3 at 0xafcc: file String.cc, line 846. | |
3152 | Multiple breakpoints were set. | |
3153 | Use the "delete" command to delete unwanted | |
3154 | breakpoints. | |
3155 | (@value{GDBP}) | |
3156 | @end group | |
3157 | @end smallexample | |
c906108c SS |
3158 | |
3159 | @c @ifclear BARETARGET | |
6d2ebf8b | 3160 | @node Error in Breakpoints |
d4f3574e | 3161 | @subsection ``Cannot insert breakpoints'' |
c906108c SS |
3162 | @c |
3163 | @c FIXME!! 14/6/95 Is there a real example of this? Let's use it. | |
3164 | @c | |
d4f3574e SS |
3165 | Under some operating systems, breakpoints cannot be used in a program if |
3166 | any other process is running that program. In this situation, | |
5d161b24 | 3167 | attempting to run or continue a program with a breakpoint causes |
d4f3574e SS |
3168 | @value{GDBN} to print an error message: |
3169 | ||
3170 | @example | |
3171 | Cannot insert breakpoints. | |
3172 | The same program may be running in another process. | |
3173 | @end example | |
3174 | ||
3175 | When this happens, you have three ways to proceed: | |
3176 | ||
3177 | @enumerate | |
3178 | @item | |
3179 | Remove or disable the breakpoints, then continue. | |
3180 | ||
3181 | @item | |
5d161b24 | 3182 | Suspend @value{GDBN}, and copy the file containing your program to a new |
d4f3574e | 3183 | name. Resume @value{GDBN} and use the @code{exec-file} command to specify |
5d161b24 | 3184 | that @value{GDBN} should run your program under that name. |
d4f3574e SS |
3185 | Then start your program again. |
3186 | ||
3187 | @item | |
3188 | Relink your program so that the text segment is nonsharable, using the | |
3189 | linker option @samp{-N}. The operating system limitation may not apply | |
3190 | to nonsharable executables. | |
3191 | @end enumerate | |
c906108c SS |
3192 | @c @end ifclear |
3193 | ||
d4f3574e SS |
3194 | A similar message can be printed if you request too many active |
3195 | hardware-assisted breakpoints and watchpoints: | |
3196 | ||
3197 | @c FIXME: the precise wording of this message may change; the relevant | |
3198 | @c source change is not committed yet (Sep 3, 1999). | |
3199 | @smallexample | |
3200 | Stopped; cannot insert breakpoints. | |
3201 | You may have requested too many hardware breakpoints and watchpoints. | |
3202 | @end smallexample | |
3203 | ||
3204 | @noindent | |
3205 | This message is printed when you attempt to resume the program, since | |
3206 | only then @value{GDBN} knows exactly how many hardware breakpoints and | |
3207 | watchpoints it needs to insert. | |
3208 | ||
3209 | When this message is printed, you need to disable or remove some of the | |
3210 | hardware-assisted breakpoints and watchpoints, and then continue. | |
3211 | ||
3212 | ||
6d2ebf8b | 3213 | @node Continuing and Stepping |
c906108c SS |
3214 | @section Continuing and stepping |
3215 | ||
3216 | @cindex stepping | |
3217 | @cindex continuing | |
3218 | @cindex resuming execution | |
3219 | @dfn{Continuing} means resuming program execution until your program | |
3220 | completes normally. In contrast, @dfn{stepping} means executing just | |
3221 | one more ``step'' of your program, where ``step'' may mean either one | |
3222 | line of source code, or one machine instruction (depending on what | |
7a292a7a SS |
3223 | particular command you use). Either when continuing or when stepping, |
3224 | your program may stop even sooner, due to a breakpoint or a signal. (If | |
d4f3574e SS |
3225 | it stops due to a signal, you may want to use @code{handle}, or use |
3226 | @samp{signal 0} to resume execution. @xref{Signals, ,Signals}.) | |
c906108c SS |
3227 | |
3228 | @table @code | |
3229 | @kindex continue | |
41afff9a EZ |
3230 | @kindex c @r{(@code{continue})} |
3231 | @kindex fg @r{(resume foreground execution)} | |
c906108c SS |
3232 | @item continue @r{[}@var{ignore-count}@r{]} |
3233 | @itemx c @r{[}@var{ignore-count}@r{]} | |
3234 | @itemx fg @r{[}@var{ignore-count}@r{]} | |
3235 | Resume program execution, at the address where your program last stopped; | |
3236 | any breakpoints set at that address are bypassed. The optional argument | |
3237 | @var{ignore-count} allows you to specify a further number of times to | |
3238 | ignore a breakpoint at this location; its effect is like that of | |
3239 | @code{ignore} (@pxref{Conditions, ,Break conditions}). | |
3240 | ||
3241 | The argument @var{ignore-count} is meaningful only when your program | |
3242 | stopped due to a breakpoint. At other times, the argument to | |
3243 | @code{continue} is ignored. | |
3244 | ||
d4f3574e SS |
3245 | The synonyms @code{c} and @code{fg} (for @dfn{foreground}, as the |
3246 | debugged program is deemed to be the foreground program) are provided | |
3247 | purely for convenience, and have exactly the same behavior as | |
3248 | @code{continue}. | |
c906108c SS |
3249 | @end table |
3250 | ||
3251 | To resume execution at a different place, you can use @code{return} | |
3252 | (@pxref{Returning, ,Returning from a function}) to go back to the | |
3253 | calling function; or @code{jump} (@pxref{Jumping, ,Continuing at a | |
3254 | different address}) to go to an arbitrary location in your program. | |
3255 | ||
3256 | A typical technique for using stepping is to set a breakpoint | |
3257 | (@pxref{Breakpoints, ,Breakpoints; watchpoints; and catchpoints}) at the | |
3258 | beginning of the function or the section of your program where a problem | |
3259 | is believed to lie, run your program until it stops at that breakpoint, | |
3260 | and then step through the suspect area, examining the variables that are | |
3261 | interesting, until you see the problem happen. | |
3262 | ||
3263 | @table @code | |
3264 | @kindex step | |
41afff9a | 3265 | @kindex s @r{(@code{step})} |
c906108c SS |
3266 | @item step |
3267 | Continue running your program until control reaches a different source | |
3268 | line, then stop it and return control to @value{GDBN}. This command is | |
3269 | abbreviated @code{s}. | |
3270 | ||
3271 | @quotation | |
3272 | @c "without debugging information" is imprecise; actually "without line | |
3273 | @c numbers in the debugging information". (gcc -g1 has debugging info but | |
3274 | @c not line numbers). But it seems complex to try to make that | |
3275 | @c distinction here. | |
3276 | @emph{Warning:} If you use the @code{step} command while control is | |
3277 | within a function that was compiled without debugging information, | |
3278 | execution proceeds until control reaches a function that does have | |
3279 | debugging information. Likewise, it will not step into a function which | |
3280 | is compiled without debugging information. To step through functions | |
3281 | without debugging information, use the @code{stepi} command, described | |
3282 | below. | |
3283 | @end quotation | |
3284 | ||
4a92d011 EZ |
3285 | The @code{step} command only stops at the first instruction of a source |
3286 | line. This prevents the multiple stops that could otherwise occur in | |
3287 | @code{switch} statements, @code{for} loops, etc. @code{step} continues | |
3288 | to stop if a function that has debugging information is called within | |
3289 | the line. In other words, @code{step} @emph{steps inside} any functions | |
3290 | called within the line. | |
c906108c | 3291 | |
d4f3574e SS |
3292 | Also, the @code{step} command only enters a function if there is line |
3293 | number information for the function. Otherwise it acts like the | |
5d161b24 | 3294 | @code{next} command. This avoids problems when using @code{cc -gl} |
c906108c | 3295 | on MIPS machines. Previously, @code{step} entered subroutines if there |
5d161b24 | 3296 | was any debugging information about the routine. |
c906108c SS |
3297 | |
3298 | @item step @var{count} | |
3299 | Continue running as in @code{step}, but do so @var{count} times. If a | |
7a292a7a SS |
3300 | breakpoint is reached, or a signal not related to stepping occurs before |
3301 | @var{count} steps, stepping stops right away. | |
c906108c SS |
3302 | |
3303 | @kindex next | |
41afff9a | 3304 | @kindex n @r{(@code{next})} |
c906108c SS |
3305 | @item next @r{[}@var{count}@r{]} |
3306 | Continue to the next source line in the current (innermost) stack frame. | |
7a292a7a SS |
3307 | This is similar to @code{step}, but function calls that appear within |
3308 | the line of code are executed without stopping. Execution stops when | |
3309 | control reaches a different line of code at the original stack level | |
3310 | that was executing when you gave the @code{next} command. This command | |
3311 | is abbreviated @code{n}. | |
c906108c SS |
3312 | |
3313 | An argument @var{count} is a repeat count, as for @code{step}. | |
3314 | ||
3315 | ||
3316 | @c FIX ME!! Do we delete this, or is there a way it fits in with | |
3317 | @c the following paragraph? --- Vctoria | |
3318 | @c | |
3319 | @c @code{next} within a function that lacks debugging information acts like | |
3320 | @c @code{step}, but any function calls appearing within the code of the | |
3321 | @c function are executed without stopping. | |
3322 | ||
d4f3574e SS |
3323 | The @code{next} command only stops at the first instruction of a |
3324 | source line. This prevents multiple stops that could otherwise occur in | |
4a92d011 | 3325 | @code{switch} statements, @code{for} loops, etc. |
c906108c | 3326 | |
b90a5f51 CF |
3327 | @kindex set step-mode |
3328 | @item set step-mode | |
3329 | @cindex functions without line info, and stepping | |
3330 | @cindex stepping into functions with no line info | |
3331 | @itemx set step-mode on | |
4a92d011 | 3332 | The @code{set step-mode on} command causes the @code{step} command to |
b90a5f51 CF |
3333 | stop at the first instruction of a function which contains no debug line |
3334 | information rather than stepping over it. | |
3335 | ||
4a92d011 EZ |
3336 | This is useful in cases where you may be interested in inspecting the |
3337 | machine instructions of a function which has no symbolic info and do not | |
3338 | want @value{GDBN} to automatically skip over this function. | |
b90a5f51 CF |
3339 | |
3340 | @item set step-mode off | |
4a92d011 | 3341 | Causes the @code{step} command to step over any functions which contains no |
b90a5f51 CF |
3342 | debug information. This is the default. |
3343 | ||
c906108c SS |
3344 | @kindex finish |
3345 | @item finish | |
3346 | Continue running until just after function in the selected stack frame | |
3347 | returns. Print the returned value (if any). | |
3348 | ||
3349 | Contrast this with the @code{return} command (@pxref{Returning, | |
3350 | ,Returning from a function}). | |
3351 | ||
3352 | @kindex until | |
41afff9a | 3353 | @kindex u @r{(@code{until})} |
c906108c SS |
3354 | @item until |
3355 | @itemx u | |
3356 | Continue running until a source line past the current line, in the | |
3357 | current stack frame, is reached. This command is used to avoid single | |
3358 | stepping through a loop more than once. It is like the @code{next} | |
3359 | command, except that when @code{until} encounters a jump, it | |
3360 | automatically continues execution until the program counter is greater | |
3361 | than the address of the jump. | |
3362 | ||
3363 | This means that when you reach the end of a loop after single stepping | |
3364 | though it, @code{until} makes your program continue execution until it | |
3365 | exits the loop. In contrast, a @code{next} command at the end of a loop | |
3366 | simply steps back to the beginning of the loop, which forces you to step | |
3367 | through the next iteration. | |
3368 | ||
3369 | @code{until} always stops your program if it attempts to exit the current | |
3370 | stack frame. | |
3371 | ||
3372 | @code{until} may produce somewhat counterintuitive results if the order | |
3373 | of machine code does not match the order of the source lines. For | |
3374 | example, in the following excerpt from a debugging session, the @code{f} | |
3375 | (@code{frame}) command shows that execution is stopped at line | |
3376 | @code{206}; yet when we use @code{until}, we get to line @code{195}: | |
3377 | ||
3378 | @example | |
3379 | (@value{GDBP}) f | |
3380 | #0 main (argc=4, argv=0xf7fffae8) at m4.c:206 | |
3381 | 206 expand_input(); | |
3382 | (@value{GDBP}) until | |
3383 | 195 for ( ; argc > 0; NEXTARG) @{ | |
3384 | @end example | |
3385 | ||
3386 | This happened because, for execution efficiency, the compiler had | |
3387 | generated code for the loop closure test at the end, rather than the | |
3388 | start, of the loop---even though the test in a C @code{for}-loop is | |
3389 | written before the body of the loop. The @code{until} command appeared | |
3390 | to step back to the beginning of the loop when it advanced to this | |
3391 | expression; however, it has not really gone to an earlier | |
3392 | statement---not in terms of the actual machine code. | |
3393 | ||
3394 | @code{until} with no argument works by means of single | |
3395 | instruction stepping, and hence is slower than @code{until} with an | |
3396 | argument. | |
3397 | ||
3398 | @item until @var{location} | |
3399 | @itemx u @var{location} | |
3400 | Continue running your program until either the specified location is | |
3401 | reached, or the current stack frame returns. @var{location} is any of | |
3402 | the forms of argument acceptable to @code{break} (@pxref{Set Breaks, | |
3403 | ,Setting breakpoints}). This form of the command uses breakpoints, | |
3404 | and hence is quicker than @code{until} without an argument. | |
3405 | ||
3406 | @kindex stepi | |
41afff9a | 3407 | @kindex si @r{(@code{stepi})} |
c906108c | 3408 | @item stepi |
96a2c332 | 3409 | @itemx stepi @var{arg} |
c906108c SS |
3410 | @itemx si |
3411 | Execute one machine instruction, then stop and return to the debugger. | |
3412 | ||
3413 | It is often useful to do @samp{display/i $pc} when stepping by machine | |
3414 | instructions. This makes @value{GDBN} automatically display the next | |
3415 | instruction to be executed, each time your program stops. @xref{Auto | |
3416 | Display,, Automatic display}. | |
3417 | ||
3418 | An argument is a repeat count, as in @code{step}. | |
3419 | ||
3420 | @need 750 | |
3421 | @kindex nexti | |
41afff9a | 3422 | @kindex ni @r{(@code{nexti})} |
c906108c | 3423 | @item nexti |
96a2c332 | 3424 | @itemx nexti @var{arg} |
c906108c SS |
3425 | @itemx ni |
3426 | Execute one machine instruction, but if it is a function call, | |
3427 | proceed until the function returns. | |
3428 | ||
3429 | An argument is a repeat count, as in @code{next}. | |
3430 | @end table | |
3431 | ||
6d2ebf8b | 3432 | @node Signals |
c906108c SS |
3433 | @section Signals |
3434 | @cindex signals | |
3435 | ||
3436 | A signal is an asynchronous event that can happen in a program. The | |
3437 | operating system defines the possible kinds of signals, and gives each | |
3438 | kind a name and a number. For example, in Unix @code{SIGINT} is the | |
d4f3574e | 3439 | signal a program gets when you type an interrupt character (often @kbd{C-c}); |
c906108c SS |
3440 | @code{SIGSEGV} is the signal a program gets from referencing a place in |
3441 | memory far away from all the areas in use; @code{SIGALRM} occurs when | |
3442 | the alarm clock timer goes off (which happens only if your program has | |
3443 | requested an alarm). | |
3444 | ||
3445 | @cindex fatal signals | |
3446 | Some signals, including @code{SIGALRM}, are a normal part of the | |
3447 | functioning of your program. Others, such as @code{SIGSEGV}, indicate | |
d4f3574e | 3448 | errors; these signals are @dfn{fatal} (they kill your program immediately) if the |
c906108c SS |
3449 | program has not specified in advance some other way to handle the signal. |
3450 | @code{SIGINT} does not indicate an error in your program, but it is normally | |
3451 | fatal so it can carry out the purpose of the interrupt: to kill the program. | |
3452 | ||
3453 | @value{GDBN} has the ability to detect any occurrence of a signal in your | |
3454 | program. You can tell @value{GDBN} in advance what to do for each kind of | |
3455 | signal. | |
3456 | ||
3457 | @cindex handling signals | |
3458 | Normally, @value{GDBN} is set up to ignore non-erroneous signals like @code{SIGALRM} | |
3459 | (so as not to interfere with their role in the functioning of your program) | |
3460 | but to stop your program immediately whenever an error signal happens. | |
3461 | You can change these settings with the @code{handle} command. | |
3462 | ||
3463 | @table @code | |
3464 | @kindex info signals | |
3465 | @item info signals | |
96a2c332 | 3466 | @itemx info handle |
c906108c SS |
3467 | Print a table of all the kinds of signals and how @value{GDBN} has been told to |
3468 | handle each one. You can use this to see the signal numbers of all | |
3469 | the defined types of signals. | |
3470 | ||
d4f3574e | 3471 | @code{info handle} is an alias for @code{info signals}. |
c906108c SS |
3472 | |
3473 | @kindex handle | |
3474 | @item handle @var{signal} @var{keywords}@dots{} | |
5d161b24 | 3475 | Change the way @value{GDBN} handles signal @var{signal}. @var{signal} can |
c906108c SS |
3476 | be the number of a signal or its name (with or without the @samp{SIG} at the |
3477 | beginning). The @var{keywords} say what change to make. | |
3478 | @end table | |
3479 | ||
3480 | @c @group | |
3481 | The keywords allowed by the @code{handle} command can be abbreviated. | |
3482 | Their full names are: | |
3483 | ||
3484 | @table @code | |
3485 | @item nostop | |
3486 | @value{GDBN} should not stop your program when this signal happens. It may | |
3487 | still print a message telling you that the signal has come in. | |
3488 | ||
3489 | @item stop | |
3490 | @value{GDBN} should stop your program when this signal happens. This implies | |
3491 | the @code{print} keyword as well. | |
3492 | ||
3493 | @item print | |
3494 | @value{GDBN} should print a message when this signal happens. | |
3495 | ||
3496 | @item noprint | |
3497 | @value{GDBN} should not mention the occurrence of the signal at all. This | |
3498 | implies the @code{nostop} keyword as well. | |
3499 | ||
3500 | @item pass | |
3501 | @value{GDBN} should allow your program to see this signal; your program | |
3502 | can handle the signal, or else it may terminate if the signal is fatal | |
3503 | and not handled. | |
3504 | ||
3505 | @item nopass | |
3506 | @value{GDBN} should not allow your program to see this signal. | |
3507 | @end table | |
3508 | @c @end group | |
3509 | ||
d4f3574e SS |
3510 | When a signal stops your program, the signal is not visible to the |
3511 | program until you | |
c906108c SS |
3512 | continue. Your program sees the signal then, if @code{pass} is in |
3513 | effect for the signal in question @emph{at that time}. In other words, | |
3514 | after @value{GDBN} reports a signal, you can use the @code{handle} | |
3515 | command with @code{pass} or @code{nopass} to control whether your | |
3516 | program sees that signal when you continue. | |
3517 | ||
3518 | You can also use the @code{signal} command to prevent your program from | |
3519 | seeing a signal, or cause it to see a signal it normally would not see, | |
3520 | or to give it any signal at any time. For example, if your program stopped | |
3521 | due to some sort of memory reference error, you might store correct | |
3522 | values into the erroneous variables and continue, hoping to see more | |
3523 | execution; but your program would probably terminate immediately as | |
3524 | a result of the fatal signal once it saw the signal. To prevent this, | |
3525 | you can continue with @samp{signal 0}. @xref{Signaling, ,Giving your | |
5d161b24 | 3526 | program a signal}. |
c906108c | 3527 | |
6d2ebf8b | 3528 | @node Thread Stops |
c906108c SS |
3529 | @section Stopping and starting multi-thread programs |
3530 | ||
3531 | When your program has multiple threads (@pxref{Threads,, Debugging | |
3532 | programs with multiple threads}), you can choose whether to set | |
3533 | breakpoints on all threads, or on a particular thread. | |
3534 | ||
3535 | @table @code | |
3536 | @cindex breakpoints and threads | |
3537 | @cindex thread breakpoints | |
3538 | @kindex break @dots{} thread @var{threadno} | |
3539 | @item break @var{linespec} thread @var{threadno} | |
3540 | @itemx break @var{linespec} thread @var{threadno} if @dots{} | |
3541 | @var{linespec} specifies source lines; there are several ways of | |
3542 | writing them, but the effect is always to specify some source line. | |
3543 | ||
3544 | Use the qualifier @samp{thread @var{threadno}} with a breakpoint command | |
3545 | to specify that you only want @value{GDBN} to stop the program when a | |
3546 | particular thread reaches this breakpoint. @var{threadno} is one of the | |
3547 | numeric thread identifiers assigned by @value{GDBN}, shown in the first | |
3548 | column of the @samp{info threads} display. | |
3549 | ||
3550 | If you do not specify @samp{thread @var{threadno}} when you set a | |
3551 | breakpoint, the breakpoint applies to @emph{all} threads of your | |
3552 | program. | |
3553 | ||
3554 | You can use the @code{thread} qualifier on conditional breakpoints as | |
3555 | well; in this case, place @samp{thread @var{threadno}} before the | |
3556 | breakpoint condition, like this: | |
3557 | ||
3558 | @smallexample | |
2df3850c | 3559 | (@value{GDBP}) break frik.c:13 thread 28 if bartab > lim |
c906108c SS |
3560 | @end smallexample |
3561 | ||
3562 | @end table | |
3563 | ||
3564 | @cindex stopped threads | |
3565 | @cindex threads, stopped | |
3566 | Whenever your program stops under @value{GDBN} for any reason, | |
3567 | @emph{all} threads of execution stop, not just the current thread. This | |
3568 | allows you to examine the overall state of the program, including | |
3569 | switching between threads, without worrying that things may change | |
3570 | underfoot. | |
3571 | ||
3572 | @cindex continuing threads | |
3573 | @cindex threads, continuing | |
3574 | Conversely, whenever you restart the program, @emph{all} threads start | |
3575 | executing. @emph{This is true even when single-stepping} with commands | |
5d161b24 | 3576 | like @code{step} or @code{next}. |
c906108c SS |
3577 | |
3578 | In particular, @value{GDBN} cannot single-step all threads in lockstep. | |
3579 | Since thread scheduling is up to your debugging target's operating | |
3580 | system (not controlled by @value{GDBN}), other threads may | |
3581 | execute more than one statement while the current thread completes a | |
3582 | single step. Moreover, in general other threads stop in the middle of a | |
3583 | statement, rather than at a clean statement boundary, when the program | |
3584 | stops. | |
3585 | ||
3586 | You might even find your program stopped in another thread after | |
3587 | continuing or even single-stepping. This happens whenever some other | |
3588 | thread runs into a breakpoint, a signal, or an exception before the | |
3589 | first thread completes whatever you requested. | |
3590 | ||
3591 | On some OSes, you can lock the OS scheduler and thus allow only a single | |
3592 | thread to run. | |
3593 | ||
3594 | @table @code | |
3595 | @item set scheduler-locking @var{mode} | |
3596 | Set the scheduler locking mode. If it is @code{off}, then there is no | |
3597 | locking and any thread may run at any time. If @code{on}, then only the | |
3598 | current thread may run when the inferior is resumed. The @code{step} | |
3599 | mode optimizes for single-stepping. It stops other threads from | |
3600 | ``seizing the prompt'' by preempting the current thread while you are | |
3601 | stepping. Other threads will only rarely (or never) get a chance to run | |
d4f3574e | 3602 | when you step. They are more likely to run when you @samp{next} over a |
c906108c | 3603 | function call, and they are completely free to run when you use commands |
d4f3574e | 3604 | like @samp{continue}, @samp{until}, or @samp{finish}. However, unless another |
c906108c | 3605 | thread hits a breakpoint during its timeslice, they will never steal the |
2df3850c | 3606 | @value{GDBN} prompt away from the thread that you are debugging. |
c906108c SS |
3607 | |
3608 | @item show scheduler-locking | |
3609 | Display the current scheduler locking mode. | |
3610 | @end table | |
3611 | ||
c906108c | 3612 | |
6d2ebf8b | 3613 | @node Stack |
c906108c SS |
3614 | @chapter Examining the Stack |
3615 | ||
3616 | When your program has stopped, the first thing you need to know is where it | |
3617 | stopped and how it got there. | |
3618 | ||
3619 | @cindex call stack | |
5d161b24 DB |
3620 | Each time your program performs a function call, information about the call |
3621 | is generated. | |
3622 | That information includes the location of the call in your program, | |
3623 | the arguments of the call, | |
c906108c | 3624 | and the local variables of the function being called. |
5d161b24 | 3625 | The information is saved in a block of data called a @dfn{stack frame}. |
c906108c SS |
3626 | The stack frames are allocated in a region of memory called the @dfn{call |
3627 | stack}. | |
3628 | ||
3629 | When your program stops, the @value{GDBN} commands for examining the | |
3630 | stack allow you to see all of this information. | |
3631 | ||
3632 | @cindex selected frame | |
3633 | One of the stack frames is @dfn{selected} by @value{GDBN} and many | |
3634 | @value{GDBN} commands refer implicitly to the selected frame. In | |
3635 | particular, whenever you ask @value{GDBN} for the value of a variable in | |
3636 | your program, the value is found in the selected frame. There are | |
3637 | special @value{GDBN} commands to select whichever frame you are | |
3638 | interested in. @xref{Selection, ,Selecting a frame}. | |
3639 | ||
3640 | When your program stops, @value{GDBN} automatically selects the | |
5d161b24 | 3641 | currently executing frame and describes it briefly, similar to the |
c906108c SS |
3642 | @code{frame} command (@pxref{Frame Info, ,Information about a frame}). |
3643 | ||
3644 | @menu | |
3645 | * Frames:: Stack frames | |
3646 | * Backtrace:: Backtraces | |
3647 | * Selection:: Selecting a frame | |
3648 | * Frame Info:: Information on a frame | |
c906108c SS |
3649 | |
3650 | @end menu | |
3651 | ||
6d2ebf8b | 3652 | @node Frames |
c906108c SS |
3653 | @section Stack frames |
3654 | ||
d4f3574e | 3655 | @cindex frame, definition |
c906108c SS |
3656 | @cindex stack frame |
3657 | The call stack is divided up into contiguous pieces called @dfn{stack | |
3658 | frames}, or @dfn{frames} for short; each frame is the data associated | |
3659 | with one call to one function. The frame contains the arguments given | |
3660 | to the function, the function's local variables, and the address at | |
3661 | which the function is executing. | |
3662 | ||
3663 | @cindex initial frame | |
3664 | @cindex outermost frame | |
3665 | @cindex innermost frame | |
3666 | When your program is started, the stack has only one frame, that of the | |
3667 | function @code{main}. This is called the @dfn{initial} frame or the | |
3668 | @dfn{outermost} frame. Each time a function is called, a new frame is | |
3669 | made. Each time a function returns, the frame for that function invocation | |
3670 | is eliminated. If a function is recursive, there can be many frames for | |
3671 | the same function. The frame for the function in which execution is | |
3672 | actually occurring is called the @dfn{innermost} frame. This is the most | |
3673 | recently created of all the stack frames that still exist. | |
3674 | ||
3675 | @cindex frame pointer | |
3676 | Inside your program, stack frames are identified by their addresses. A | |
3677 | stack frame consists of many bytes, each of which has its own address; each | |
3678 | kind of computer has a convention for choosing one byte whose | |
3679 | address serves as the address of the frame. Usually this address is kept | |
3680 | in a register called the @dfn{frame pointer register} while execution is | |
3681 | going on in that frame. | |
3682 | ||
3683 | @cindex frame number | |
3684 | @value{GDBN} assigns numbers to all existing stack frames, starting with | |
3685 | zero for the innermost frame, one for the frame that called it, | |
3686 | and so on upward. These numbers do not really exist in your program; | |
3687 | they are assigned by @value{GDBN} to give you a way of designating stack | |
3688 | frames in @value{GDBN} commands. | |
3689 | ||
6d2ebf8b SS |
3690 | @c The -fomit-frame-pointer below perennially causes hbox overflow |
3691 | @c underflow problems. | |
c906108c SS |
3692 | @cindex frameless execution |
3693 | Some compilers provide a way to compile functions so that they operate | |
6d2ebf8b SS |
3694 | without stack frames. (For example, the @value{GCC} option |
3695 | @example | |
3696 | @samp{-fomit-frame-pointer} | |
3697 | @end example | |
3698 | generates functions without a frame.) | |
c906108c SS |
3699 | This is occasionally done with heavily used library functions to save |
3700 | the frame setup time. @value{GDBN} has limited facilities for dealing | |
3701 | with these function invocations. If the innermost function invocation | |
3702 | has no stack frame, @value{GDBN} nevertheless regards it as though | |
3703 | it had a separate frame, which is numbered zero as usual, allowing | |
3704 | correct tracing of the function call chain. However, @value{GDBN} has | |
3705 | no provision for frameless functions elsewhere in the stack. | |
3706 | ||
3707 | @table @code | |
d4f3574e | 3708 | @kindex frame@r{, command} |
41afff9a | 3709 | @cindex current stack frame |
c906108c | 3710 | @item frame @var{args} |
5d161b24 | 3711 | The @code{frame} command allows you to move from one stack frame to another, |
c906108c | 3712 | and to print the stack frame you select. @var{args} may be either the |
5d161b24 DB |
3713 | address of the frame or the stack frame number. Without an argument, |
3714 | @code{frame} prints the current stack frame. | |
c906108c SS |
3715 | |
3716 | @kindex select-frame | |
41afff9a | 3717 | @cindex selecting frame silently |
c906108c SS |
3718 | @item select-frame |
3719 | The @code{select-frame} command allows you to move from one stack frame | |
3720 | to another without printing the frame. This is the silent version of | |
3721 | @code{frame}. | |
3722 | @end table | |
3723 | ||
6d2ebf8b | 3724 | @node Backtrace |
c906108c SS |
3725 | @section Backtraces |
3726 | ||
3727 | @cindex backtraces | |
3728 | @cindex tracebacks | |
3729 | @cindex stack traces | |
3730 | A backtrace is a summary of how your program got where it is. It shows one | |
3731 | line per frame, for many frames, starting with the currently executing | |
3732 | frame (frame zero), followed by its caller (frame one), and on up the | |
3733 | stack. | |
3734 | ||
3735 | @table @code | |
3736 | @kindex backtrace | |
41afff9a | 3737 | @kindex bt @r{(@code{backtrace})} |
c906108c SS |
3738 | @item backtrace |
3739 | @itemx bt | |
3740 | Print a backtrace of the entire stack: one line per frame for all | |
3741 | frames in the stack. | |
3742 | ||
3743 | You can stop the backtrace at any time by typing the system interrupt | |
3744 | character, normally @kbd{C-c}. | |
3745 | ||
3746 | @item backtrace @var{n} | |
3747 | @itemx bt @var{n} | |
3748 | Similar, but print only the innermost @var{n} frames. | |
3749 | ||
3750 | @item backtrace -@var{n} | |
3751 | @itemx bt -@var{n} | |
3752 | Similar, but print only the outermost @var{n} frames. | |
3753 | @end table | |
3754 | ||
3755 | @kindex where | |
3756 | @kindex info stack | |
41afff9a | 3757 | @kindex info s @r{(@code{info stack})} |
c906108c SS |
3758 | The names @code{where} and @code{info stack} (abbreviated @code{info s}) |
3759 | are additional aliases for @code{backtrace}. | |
3760 | ||
3761 | Each line in the backtrace shows the frame number and the function name. | |
3762 | The program counter value is also shown---unless you use @code{set | |
3763 | print address off}. The backtrace also shows the source file name and | |
3764 | line number, as well as the arguments to the function. The program | |
3765 | counter value is omitted if it is at the beginning of the code for that | |
3766 | line number. | |
3767 | ||
3768 | Here is an example of a backtrace. It was made with the command | |
3769 | @samp{bt 3}, so it shows the innermost three frames. | |
3770 | ||
3771 | @smallexample | |
3772 | @group | |
5d161b24 | 3773 | #0 m4_traceon (obs=0x24eb0, argc=1, argv=0x2b8c8) |
c906108c SS |
3774 | at builtin.c:993 |
3775 | #1 0x6e38 in expand_macro (sym=0x2b600) at macro.c:242 | |
3776 | #2 0x6840 in expand_token (obs=0x0, t=177664, td=0xf7fffb08) | |
3777 | at macro.c:71 | |
3778 | (More stack frames follow...) | |
3779 | @end group | |
3780 | @end smallexample | |
3781 | ||
3782 | @noindent | |
3783 | The display for frame zero does not begin with a program counter | |
3784 | value, indicating that your program has stopped at the beginning of the | |
3785 | code for line @code{993} of @code{builtin.c}. | |
3786 | ||
6d2ebf8b | 3787 | @node Selection |
c906108c SS |
3788 | @section Selecting a frame |
3789 | ||
3790 | Most commands for examining the stack and other data in your program work on | |
3791 | whichever stack frame is selected at the moment. Here are the commands for | |
3792 | selecting a stack frame; all of them finish by printing a brief description | |
3793 | of the stack frame just selected. | |
3794 | ||
3795 | @table @code | |
d4f3574e | 3796 | @kindex frame@r{, selecting} |
41afff9a | 3797 | @kindex f @r{(@code{frame})} |
c906108c SS |
3798 | @item frame @var{n} |
3799 | @itemx f @var{n} | |
3800 | Select frame number @var{n}. Recall that frame zero is the innermost | |
3801 | (currently executing) frame, frame one is the frame that called the | |
3802 | innermost one, and so on. The highest-numbered frame is the one for | |
3803 | @code{main}. | |
3804 | ||
3805 | @item frame @var{addr} | |
3806 | @itemx f @var{addr} | |
3807 | Select the frame at address @var{addr}. This is useful mainly if the | |
3808 | chaining of stack frames has been damaged by a bug, making it | |
3809 | impossible for @value{GDBN} to assign numbers properly to all frames. In | |
3810 | addition, this can be useful when your program has multiple stacks and | |
3811 | switches between them. | |
3812 | ||
c906108c SS |
3813 | On the SPARC architecture, @code{frame} needs two addresses to |
3814 | select an arbitrary frame: a frame pointer and a stack pointer. | |
3815 | ||
3816 | On the MIPS and Alpha architecture, it needs two addresses: a stack | |
3817 | pointer and a program counter. | |
3818 | ||
3819 | On the 29k architecture, it needs three addresses: a register stack | |
3820 | pointer, a program counter, and a memory stack pointer. | |
3821 | @c note to future updaters: this is conditioned on a flag | |
3822 | @c SETUP_ARBITRARY_FRAME in the tm-*.h files. The above is up to date | |
3823 | @c as of 27 Jan 1994. | |
c906108c SS |
3824 | |
3825 | @kindex up | |
3826 | @item up @var{n} | |
3827 | Move @var{n} frames up the stack. For positive numbers @var{n}, this | |
3828 | advances toward the outermost frame, to higher frame numbers, to frames | |
3829 | that have existed longer. @var{n} defaults to one. | |
3830 | ||
3831 | @kindex down | |
41afff9a | 3832 | @kindex do @r{(@code{down})} |
c906108c SS |
3833 | @item down @var{n} |
3834 | Move @var{n} frames down the stack. For positive numbers @var{n}, this | |
3835 | advances toward the innermost frame, to lower frame numbers, to frames | |
3836 | that were created more recently. @var{n} defaults to one. You may | |
3837 | abbreviate @code{down} as @code{do}. | |
3838 | @end table | |
3839 | ||
3840 | All of these commands end by printing two lines of output describing the | |
3841 | frame. The first line shows the frame number, the function name, the | |
3842 | arguments, and the source file and line number of execution in that | |
5d161b24 | 3843 | frame. The second line shows the text of that source line. |
c906108c SS |
3844 | |
3845 | @need 1000 | |
3846 | For example: | |
3847 | ||
3848 | @smallexample | |
3849 | @group | |
3850 | (@value{GDBP}) up | |
3851 | #1 0x22f0 in main (argc=1, argv=0xf7fffbf4, env=0xf7fffbfc) | |
3852 | at env.c:10 | |
3853 | 10 read_input_file (argv[i]); | |
3854 | @end group | |
3855 | @end smallexample | |
3856 | ||
3857 | After such a printout, the @code{list} command with no arguments | |
3858 | prints ten lines centered on the point of execution in the frame. | |
3859 | @xref{List, ,Printing source lines}. | |
3860 | ||
3861 | @table @code | |
3862 | @kindex down-silently | |
3863 | @kindex up-silently | |
3864 | @item up-silently @var{n} | |
3865 | @itemx down-silently @var{n} | |
3866 | These two commands are variants of @code{up} and @code{down}, | |
3867 | respectively; they differ in that they do their work silently, without | |
3868 | causing display of the new frame. They are intended primarily for use | |
3869 | in @value{GDBN} command scripts, where the output might be unnecessary and | |
3870 | distracting. | |
3871 | @end table | |
3872 | ||
6d2ebf8b | 3873 | @node Frame Info |
c906108c SS |
3874 | @section Information about a frame |
3875 | ||
3876 | There are several other commands to print information about the selected | |
3877 | stack frame. | |
3878 | ||
3879 | @table @code | |
3880 | @item frame | |
3881 | @itemx f | |
3882 | When used without any argument, this command does not change which | |
3883 | frame is selected, but prints a brief description of the currently | |
3884 | selected stack frame. It can be abbreviated @code{f}. With an | |
3885 | argument, this command is used to select a stack frame. | |
3886 | @xref{Selection, ,Selecting a frame}. | |
3887 | ||
3888 | @kindex info frame | |
41afff9a | 3889 | @kindex info f @r{(@code{info frame})} |
c906108c SS |
3890 | @item info frame |
3891 | @itemx info f | |
3892 | This command prints a verbose description of the selected stack frame, | |
3893 | including: | |
3894 | ||
3895 | @itemize @bullet | |
5d161b24 DB |
3896 | @item |
3897 | the address of the frame | |
c906108c SS |
3898 | @item |
3899 | the address of the next frame down (called by this frame) | |
3900 | @item | |
3901 | the address of the next frame up (caller of this frame) | |
3902 | @item | |
3903 | the language in which the source code corresponding to this frame is written | |
3904 | @item | |
3905 | the address of the frame's arguments | |
3906 | @item | |
d4f3574e SS |
3907 | the address of the frame's local variables |
3908 | @item | |
c906108c SS |
3909 | the program counter saved in it (the address of execution in the caller frame) |
3910 | @item | |
3911 | which registers were saved in the frame | |
3912 | @end itemize | |
3913 | ||
3914 | @noindent The verbose description is useful when | |
3915 | something has gone wrong that has made the stack format fail to fit | |
3916 | the usual conventions. | |
3917 | ||
3918 | @item info frame @var{addr} | |
3919 | @itemx info f @var{addr} | |
3920 | Print a verbose description of the frame at address @var{addr}, without | |
3921 | selecting that frame. The selected frame remains unchanged by this | |
3922 | command. This requires the same kind of address (more than one for some | |
3923 | architectures) that you specify in the @code{frame} command. | |
3924 | @xref{Selection, ,Selecting a frame}. | |
3925 | ||
3926 | @kindex info args | |
3927 | @item info args | |
3928 | Print the arguments of the selected frame, each on a separate line. | |
3929 | ||
3930 | @item info locals | |
3931 | @kindex info locals | |
3932 | Print the local variables of the selected frame, each on a separate | |
3933 | line. These are all variables (declared either static or automatic) | |
3934 | accessible at the point of execution of the selected frame. | |
3935 | ||
c906108c | 3936 | @kindex info catch |
d4f3574e SS |
3937 | @cindex catch exceptions, list active handlers |
3938 | @cindex exception handlers, how to list | |
c906108c SS |
3939 | @item info catch |
3940 | Print a list of all the exception handlers that are active in the | |
3941 | current stack frame at the current point of execution. To see other | |
3942 | exception handlers, visit the associated frame (using the @code{up}, | |
3943 | @code{down}, or @code{frame} commands); then type @code{info catch}. | |
3944 | @xref{Set Catchpoints, , Setting catchpoints}. | |
53a5351d | 3945 | |
c906108c SS |
3946 | @end table |
3947 | ||
c906108c | 3948 | |
6d2ebf8b | 3949 | @node Source |
c906108c SS |
3950 | @chapter Examining Source Files |
3951 | ||
3952 | @value{GDBN} can print parts of your program's source, since the debugging | |
3953 | information recorded in the program tells @value{GDBN} what source files were | |
3954 | used to build it. When your program stops, @value{GDBN} spontaneously prints | |
3955 | the line where it stopped. Likewise, when you select a stack frame | |
3956 | (@pxref{Selection, ,Selecting a frame}), @value{GDBN} prints the line where | |
3957 | execution in that frame has stopped. You can print other portions of | |
3958 | source files by explicit command. | |
3959 | ||
7a292a7a | 3960 | If you use @value{GDBN} through its @sc{gnu} Emacs interface, you may |
d4f3574e | 3961 | prefer to use Emacs facilities to view source; see @ref{Emacs, ,Using |
7a292a7a | 3962 | @value{GDBN} under @sc{gnu} Emacs}. |
c906108c SS |
3963 | |
3964 | @menu | |
3965 | * List:: Printing source lines | |
c906108c | 3966 | * Search:: Searching source files |
c906108c SS |
3967 | * Source Path:: Specifying source directories |
3968 | * Machine Code:: Source and machine code | |
3969 | @end menu | |
3970 | ||
6d2ebf8b | 3971 | @node List |
c906108c SS |
3972 | @section Printing source lines |
3973 | ||
3974 | @kindex list | |
41afff9a | 3975 | @kindex l @r{(@code{list})} |
c906108c | 3976 | To print lines from a source file, use the @code{list} command |
5d161b24 | 3977 | (abbreviated @code{l}). By default, ten lines are printed. |
c906108c SS |
3978 | There are several ways to specify what part of the file you want to print. |
3979 | ||
3980 | Here are the forms of the @code{list} command most commonly used: | |
3981 | ||
3982 | @table @code | |
3983 | @item list @var{linenum} | |
3984 | Print lines centered around line number @var{linenum} in the | |
3985 | current source file. | |
3986 | ||
3987 | @item list @var{function} | |
3988 | Print lines centered around the beginning of function | |
3989 | @var{function}. | |
3990 | ||
3991 | @item list | |
3992 | Print more lines. If the last lines printed were printed with a | |
3993 | @code{list} command, this prints lines following the last lines | |
3994 | printed; however, if the last line printed was a solitary line printed | |
3995 | as part of displaying a stack frame (@pxref{Stack, ,Examining the | |
3996 | Stack}), this prints lines centered around that line. | |
3997 | ||
3998 | @item list - | |
3999 | Print lines just before the lines last printed. | |
4000 | @end table | |
4001 | ||
4002 | By default, @value{GDBN} prints ten source lines with any of these forms of | |
4003 | the @code{list} command. You can change this using @code{set listsize}: | |
4004 | ||
4005 | @table @code | |
4006 | @kindex set listsize | |
4007 | @item set listsize @var{count} | |
4008 | Make the @code{list} command display @var{count} source lines (unless | |
4009 | the @code{list} argument explicitly specifies some other number). | |
4010 | ||
4011 | @kindex show listsize | |
4012 | @item show listsize | |
4013 | Display the number of lines that @code{list} prints. | |
4014 | @end table | |
4015 | ||
4016 | Repeating a @code{list} command with @key{RET} discards the argument, | |
4017 | so it is equivalent to typing just @code{list}. This is more useful | |
4018 | than listing the same lines again. An exception is made for an | |
4019 | argument of @samp{-}; that argument is preserved in repetition so that | |
4020 | each repetition moves up in the source file. | |
4021 | ||
4022 | @cindex linespec | |
4023 | In general, the @code{list} command expects you to supply zero, one or two | |
4024 | @dfn{linespecs}. Linespecs specify source lines; there are several ways | |
d4f3574e | 4025 | of writing them, but the effect is always to specify some source line. |
c906108c SS |
4026 | Here is a complete description of the possible arguments for @code{list}: |
4027 | ||
4028 | @table @code | |
4029 | @item list @var{linespec} | |
4030 | Print lines centered around the line specified by @var{linespec}. | |
4031 | ||
4032 | @item list @var{first},@var{last} | |
4033 | Print lines from @var{first} to @var{last}. Both arguments are | |
4034 | linespecs. | |
4035 | ||
4036 | @item list ,@var{last} | |
4037 | Print lines ending with @var{last}. | |
4038 | ||
4039 | @item list @var{first}, | |
4040 | Print lines starting with @var{first}. | |
4041 | ||
4042 | @item list + | |
4043 | Print lines just after the lines last printed. | |
4044 | ||
4045 | @item list - | |
4046 | Print lines just before the lines last printed. | |
4047 | ||
4048 | @item list | |
4049 | As described in the preceding table. | |
4050 | @end table | |
4051 | ||
4052 | Here are the ways of specifying a single source line---all the | |
4053 | kinds of linespec. | |
4054 | ||
4055 | @table @code | |
4056 | @item @var{number} | |
4057 | Specifies line @var{number} of the current source file. | |
4058 | When a @code{list} command has two linespecs, this refers to | |
4059 | the same source file as the first linespec. | |
4060 | ||
4061 | @item +@var{offset} | |
4062 | Specifies the line @var{offset} lines after the last line printed. | |
4063 | When used as the second linespec in a @code{list} command that has | |
4064 | two, this specifies the line @var{offset} lines down from the | |
4065 | first linespec. | |
4066 | ||
4067 | @item -@var{offset} | |
4068 | Specifies the line @var{offset} lines before the last line printed. | |
4069 | ||
4070 | @item @var{filename}:@var{number} | |
4071 | Specifies line @var{number} in the source file @var{filename}. | |
4072 | ||
4073 | @item @var{function} | |
4074 | Specifies the line that begins the body of the function @var{function}. | |
4075 | For example: in C, this is the line with the open brace. | |
4076 | ||
4077 | @item @var{filename}:@var{function} | |
4078 | Specifies the line of the open-brace that begins the body of the | |
4079 | function @var{function} in the file @var{filename}. You only need the | |
4080 | file name with a function name to avoid ambiguity when there are | |
4081 | identically named functions in different source files. | |
4082 | ||
4083 | @item *@var{address} | |
4084 | Specifies the line containing the program address @var{address}. | |
4085 | @var{address} may be any expression. | |
4086 | @end table | |
4087 | ||
6d2ebf8b | 4088 | @node Search |
c906108c SS |
4089 | @section Searching source files |
4090 | @cindex searching | |
4091 | @kindex reverse-search | |
4092 | ||
4093 | There are two commands for searching through the current source file for a | |
4094 | regular expression. | |
4095 | ||
4096 | @table @code | |
4097 | @kindex search | |
4098 | @kindex forward-search | |
4099 | @item forward-search @var{regexp} | |
4100 | @itemx search @var{regexp} | |
4101 | The command @samp{forward-search @var{regexp}} checks each line, | |
4102 | starting with the one following the last line listed, for a match for | |
5d161b24 | 4103 | @var{regexp}. It lists the line that is found. You can use the |
c906108c SS |
4104 | synonym @samp{search @var{regexp}} or abbreviate the command name as |
4105 | @code{fo}. | |
4106 | ||
4107 | @item reverse-search @var{regexp} | |
4108 | The command @samp{reverse-search @var{regexp}} checks each line, starting | |
4109 | with the one before the last line listed and going backward, for a match | |
4110 | for @var{regexp}. It lists the line that is found. You can abbreviate | |
4111 | this command as @code{rev}. | |
4112 | @end table | |
c906108c | 4113 | |
6d2ebf8b | 4114 | @node Source Path |
c906108c SS |
4115 | @section Specifying source directories |
4116 | ||
4117 | @cindex source path | |
4118 | @cindex directories for source files | |
4119 | Executable programs sometimes do not record the directories of the source | |
4120 | files from which they were compiled, just the names. Even when they do, | |
4121 | the directories could be moved between the compilation and your debugging | |
4122 | session. @value{GDBN} has a list of directories to search for source files; | |
4123 | this is called the @dfn{source path}. Each time @value{GDBN} wants a source file, | |
4124 | it tries all the directories in the list, in the order they are present | |
4125 | in the list, until it finds a file with the desired name. Note that | |
4126 | the executable search path is @emph{not} used for this purpose. Neither is | |
4127 | the current working directory, unless it happens to be in the source | |
4128 | path. | |
4129 | ||
4130 | If @value{GDBN} cannot find a source file in the source path, and the | |
4131 | object program records a directory, @value{GDBN} tries that directory | |
4132 | too. If the source path is empty, and there is no record of the | |
4133 | compilation directory, @value{GDBN} looks in the current directory as a | |
4134 | last resort. | |
4135 | ||
4136 | Whenever you reset or rearrange the source path, @value{GDBN} clears out | |
4137 | any information it has cached about where source files are found and where | |
4138 | each line is in the file. | |
4139 | ||
4140 | @kindex directory | |
4141 | @kindex dir | |
d4f3574e SS |
4142 | When you start @value{GDBN}, its source path includes only @samp{cdir} |
4143 | and @samp{cwd}, in that order. | |
c906108c SS |
4144 | To add other directories, use the @code{directory} command. |
4145 | ||
4146 | @table @code | |
4147 | @item directory @var{dirname} @dots{} | |
4148 | @item dir @var{dirname} @dots{} | |
4149 | Add directory @var{dirname} to the front of the source path. Several | |
d4f3574e SS |
4150 | directory names may be given to this command, separated by @samp{:} |
4151 | (@samp{;} on MS-DOS and MS-Windows, where @samp{:} usually appears as | |
4152 | part of absolute file names) or | |
c906108c SS |
4153 | whitespace. You may specify a directory that is already in the source |
4154 | path; this moves it forward, so @value{GDBN} searches it sooner. | |
4155 | ||
4156 | @kindex cdir | |
4157 | @kindex cwd | |
41afff9a EZ |
4158 | @vindex $cdir@r{, convenience variable} |
4159 | @vindex $cwdr@r{, convenience variable} | |
c906108c SS |
4160 | @cindex compilation directory |
4161 | @cindex current directory | |
4162 | @cindex working directory | |
4163 | @cindex directory, current | |
4164 | @cindex directory, compilation | |
4165 | You can use the string @samp{$cdir} to refer to the compilation | |
4166 | directory (if one is recorded), and @samp{$cwd} to refer to the current | |
4167 | working directory. @samp{$cwd} is not the same as @samp{.}---the former | |
4168 | tracks the current working directory as it changes during your @value{GDBN} | |
4169 | session, while the latter is immediately expanded to the current | |
4170 | directory at the time you add an entry to the source path. | |
4171 | ||
4172 | @item directory | |
4173 | Reset the source path to empty again. This requires confirmation. | |
4174 | ||
4175 | @c RET-repeat for @code{directory} is explicitly disabled, but since | |
4176 | @c repeating it would be a no-op we do not say that. (thanks to RMS) | |
4177 | ||
4178 | @item show directories | |
4179 | @kindex show directories | |
4180 | Print the source path: show which directories it contains. | |
4181 | @end table | |
4182 | ||
4183 | If your source path is cluttered with directories that are no longer of | |
4184 | interest, @value{GDBN} may sometimes cause confusion by finding the wrong | |
4185 | versions of source. You can correct the situation as follows: | |
4186 | ||
4187 | @enumerate | |
4188 | @item | |
4189 | Use @code{directory} with no argument to reset the source path to empty. | |
4190 | ||
4191 | @item | |
4192 | Use @code{directory} with suitable arguments to reinstall the | |
4193 | directories you want in the source path. You can add all the | |
4194 | directories in one command. | |
4195 | @end enumerate | |
4196 | ||
6d2ebf8b | 4197 | @node Machine Code |
c906108c SS |
4198 | @section Source and machine code |
4199 | ||
4200 | You can use the command @code{info line} to map source lines to program | |
4201 | addresses (and vice versa), and the command @code{disassemble} to display | |
4202 | a range of addresses as machine instructions. When run under @sc{gnu} Emacs | |
d4f3574e | 4203 | mode, the @code{info line} command causes the arrow to point to the |
5d161b24 | 4204 | line specified. Also, @code{info line} prints addresses in symbolic form as |
c906108c SS |
4205 | well as hex. |
4206 | ||
4207 | @table @code | |
4208 | @kindex info line | |
4209 | @item info line @var{linespec} | |
4210 | Print the starting and ending addresses of the compiled code for | |
4211 | source line @var{linespec}. You can specify source lines in any of | |
4212 | the ways understood by the @code{list} command (@pxref{List, ,Printing | |
4213 | source lines}). | |
4214 | @end table | |
4215 | ||
4216 | For example, we can use @code{info line} to discover the location of | |
4217 | the object code for the first line of function | |
4218 | @code{m4_changequote}: | |
4219 | ||
d4f3574e SS |
4220 | @c FIXME: I think this example should also show the addresses in |
4221 | @c symbolic form, as they usually would be displayed. | |
c906108c | 4222 | @smallexample |
96a2c332 | 4223 | (@value{GDBP}) info line m4_changequote |
c906108c SS |
4224 | Line 895 of "builtin.c" starts at pc 0x634c and ends at 0x6350. |
4225 | @end smallexample | |
4226 | ||
4227 | @noindent | |
4228 | We can also inquire (using @code{*@var{addr}} as the form for | |
4229 | @var{linespec}) what source line covers a particular address: | |
4230 | @smallexample | |
4231 | (@value{GDBP}) info line *0x63ff | |
4232 | Line 926 of "builtin.c" starts at pc 0x63e4 and ends at 0x6404. | |
4233 | @end smallexample | |
4234 | ||
4235 | @cindex @code{$_} and @code{info line} | |
41afff9a | 4236 | @kindex x@r{(examine), and} info line |
c906108c SS |
4237 | After @code{info line}, the default address for the @code{x} command |
4238 | is changed to the starting address of the line, so that @samp{x/i} is | |
4239 | sufficient to begin examining the machine code (@pxref{Memory, | |
4240 | ,Examining memory}). Also, this address is saved as the value of the | |
4241 | convenience variable @code{$_} (@pxref{Convenience Vars, ,Convenience | |
4242 | variables}). | |
4243 | ||
4244 | @table @code | |
4245 | @kindex disassemble | |
4246 | @cindex assembly instructions | |
4247 | @cindex instructions, assembly | |
4248 | @cindex machine instructions | |
4249 | @cindex listing machine instructions | |
4250 | @item disassemble | |
4251 | This specialized command dumps a range of memory as machine | |
4252 | instructions. The default memory range is the function surrounding the | |
4253 | program counter of the selected frame. A single argument to this | |
4254 | command is a program counter value; @value{GDBN} dumps the function | |
4255 | surrounding this value. Two arguments specify a range of addresses | |
4256 | (first inclusive, second exclusive) to dump. | |
4257 | @end table | |
4258 | ||
c906108c SS |
4259 | The following example shows the disassembly of a range of addresses of |
4260 | HP PA-RISC 2.0 code: | |
4261 | ||
4262 | @smallexample | |
4263 | (@value{GDBP}) disas 0x32c4 0x32e4 | |
4264 | Dump of assembler code from 0x32c4 to 0x32e4: | |
4265 | 0x32c4 <main+204>: addil 0,dp | |
4266 | 0x32c8 <main+208>: ldw 0x22c(sr0,r1),r26 | |
4267 | 0x32cc <main+212>: ldil 0x3000,r31 | |
4268 | 0x32d0 <main+216>: ble 0x3f8(sr4,r31) | |
4269 | 0x32d4 <main+220>: ldo 0(r31),rp | |
4270 | 0x32d8 <main+224>: addil -0x800,dp | |
4271 | 0x32dc <main+228>: ldo 0x588(r1),r26 | |
4272 | 0x32e0 <main+232>: ldil 0x3000,r31 | |
4273 | End of assembler dump. | |
4274 | @end smallexample | |
c906108c SS |
4275 | |
4276 | Some architectures have more than one commonly-used set of instruction | |
4277 | mnemonics or other syntax. | |
4278 | ||
4279 | @table @code | |
d4f3574e | 4280 | @kindex set disassembly-flavor |
c906108c SS |
4281 | @cindex assembly instructions |
4282 | @cindex instructions, assembly | |
4283 | @cindex machine instructions | |
4284 | @cindex listing machine instructions | |
d4f3574e SS |
4285 | @cindex Intel disassembly flavor |
4286 | @cindex AT&T disassembly flavor | |
4287 | @item set disassembly-flavor @var{instruction-set} | |
c906108c SS |
4288 | Select the instruction set to use when disassembling the |
4289 | program via the @code{disassemble} or @code{x/i} commands. | |
4290 | ||
4291 | Currently this command is only defined for the Intel x86 family. You | |
d4f3574e SS |
4292 | can set @var{instruction-set} to either @code{intel} or @code{att}. |
4293 | The default is @code{att}, the AT&T flavor used by default by Unix | |
4294 | assemblers for x86-based targets. | |
c906108c SS |
4295 | @end table |
4296 | ||
4297 | ||
6d2ebf8b | 4298 | @node Data |
c906108c SS |
4299 | @chapter Examining Data |
4300 | ||
4301 | @cindex printing data | |
4302 | @cindex examining data | |
4303 | @kindex print | |
4304 | @kindex inspect | |
4305 | @c "inspect" is not quite a synonym if you are using Epoch, which we do not | |
4306 | @c document because it is nonstandard... Under Epoch it displays in a | |
4307 | @c different window or something like that. | |
4308 | The usual way to examine data in your program is with the @code{print} | |
7a292a7a SS |
4309 | command (abbreviated @code{p}), or its synonym @code{inspect}. It |
4310 | evaluates and prints the value of an expression of the language your | |
4311 | program is written in (@pxref{Languages, ,Using @value{GDBN} with | |
4312 | Different Languages}). | |
c906108c SS |
4313 | |
4314 | @table @code | |
d4f3574e SS |
4315 | @item print @var{expr} |
4316 | @itemx print /@var{f} @var{expr} | |
4317 | @var{expr} is an expression (in the source language). By default the | |
4318 | value of @var{expr} is printed in a format appropriate to its data type; | |
c906108c | 4319 | you can choose a different format by specifying @samp{/@var{f}}, where |
d4f3574e | 4320 | @var{f} is a letter specifying the format; see @ref{Output Formats,,Output |
c906108c SS |
4321 | formats}. |
4322 | ||
4323 | @item print | |
4324 | @itemx print /@var{f} | |
d4f3574e | 4325 | If you omit @var{expr}, @value{GDBN} displays the last value again (from the |
c906108c SS |
4326 | @dfn{value history}; @pxref{Value History, ,Value history}). This allows you to |
4327 | conveniently inspect the same value in an alternative format. | |
4328 | @end table | |
4329 | ||
4330 | A more low-level way of examining data is with the @code{x} command. | |
4331 | It examines data in memory at a specified address and prints it in a | |
4332 | specified format. @xref{Memory, ,Examining memory}. | |
4333 | ||
7a292a7a | 4334 | If you are interested in information about types, or about how the |
d4f3574e SS |
4335 | fields of a struct or a class are declared, use the @code{ptype @var{exp}} |
4336 | command rather than @code{print}. @xref{Symbols, ,Examining the Symbol | |
7a292a7a | 4337 | Table}. |
c906108c SS |
4338 | |
4339 | @menu | |
4340 | * Expressions:: Expressions | |
4341 | * Variables:: Program variables | |
4342 | * Arrays:: Artificial arrays | |
4343 | * Output Formats:: Output formats | |
4344 | * Memory:: Examining memory | |
4345 | * Auto Display:: Automatic display | |
4346 | * Print Settings:: Print settings | |
4347 | * Value History:: Value history | |
4348 | * Convenience Vars:: Convenience variables | |
4349 | * Registers:: Registers | |
c906108c | 4350 | * Floating Point Hardware:: Floating point hardware |
29e57380 | 4351 | * Memory Region Attributes:: Memory region attributes |
c906108c SS |
4352 | @end menu |
4353 | ||
6d2ebf8b | 4354 | @node Expressions |
c906108c SS |
4355 | @section Expressions |
4356 | ||
4357 | @cindex expressions | |
4358 | @code{print} and many other @value{GDBN} commands accept an expression and | |
4359 | compute its value. Any kind of constant, variable or operator defined | |
4360 | by the programming language you are using is valid in an expression in | |
4361 | @value{GDBN}. This includes conditional expressions, function calls, casts | |
4362 | and string constants. It unfortunately does not include symbols defined | |
4363 | by preprocessor @code{#define} commands. | |
4364 | ||
d4f3574e SS |
4365 | @value{GDBN} supports array constants in expressions input by |
4366 | the user. The syntax is @{@var{element}, @var{element}@dots{}@}. For example, | |
5d161b24 | 4367 | you can use the command @code{print @{1, 2, 3@}} to build up an array in |
d4f3574e | 4368 | memory that is @code{malloc}ed in the target program. |
c906108c | 4369 | |
c906108c SS |
4370 | Because C is so widespread, most of the expressions shown in examples in |
4371 | this manual are in C. @xref{Languages, , Using @value{GDBN} with Different | |
4372 | Languages}, for information on how to use expressions in other | |
4373 | languages. | |
4374 | ||
4375 | In this section, we discuss operators that you can use in @value{GDBN} | |
4376 | expressions regardless of your programming language. | |
4377 | ||
4378 | Casts are supported in all languages, not just in C, because it is so | |
4379 | useful to cast a number into a pointer in order to examine a structure | |
4380 | at that address in memory. | |
4381 | @c FIXME: casts supported---Mod2 true? | |
c906108c SS |
4382 | |
4383 | @value{GDBN} supports these operators, in addition to those common | |
4384 | to programming languages: | |
4385 | ||
4386 | @table @code | |
4387 | @item @@ | |
4388 | @samp{@@} is a binary operator for treating parts of memory as arrays. | |
4389 | @xref{Arrays, ,Artificial arrays}, for more information. | |
4390 | ||
4391 | @item :: | |
4392 | @samp{::} allows you to specify a variable in terms of the file or | |
4393 | function where it is defined. @xref{Variables, ,Program variables}. | |
4394 | ||
4395 | @cindex @{@var{type}@} | |
4396 | @cindex type casting memory | |
4397 | @cindex memory, viewing as typed object | |
4398 | @cindex casts, to view memory | |
4399 | @item @{@var{type}@} @var{addr} | |
4400 | Refers to an object of type @var{type} stored at address @var{addr} in | |
4401 | memory. @var{addr} may be any expression whose value is an integer or | |
4402 | pointer (but parentheses are required around binary operators, just as in | |
4403 | a cast). This construct is allowed regardless of what kind of data is | |
4404 | normally supposed to reside at @var{addr}. | |
4405 | @end table | |
4406 | ||
6d2ebf8b | 4407 | @node Variables |
c906108c SS |
4408 | @section Program variables |
4409 | ||
4410 | The most common kind of expression to use is the name of a variable | |
4411 | in your program. | |
4412 | ||
4413 | Variables in expressions are understood in the selected stack frame | |
4414 | (@pxref{Selection, ,Selecting a frame}); they must be either: | |
4415 | ||
4416 | @itemize @bullet | |
4417 | @item | |
4418 | global (or file-static) | |
4419 | @end itemize | |
4420 | ||
5d161b24 | 4421 | @noindent or |
c906108c SS |
4422 | |
4423 | @itemize @bullet | |
4424 | @item | |
4425 | visible according to the scope rules of the | |
4426 | programming language from the point of execution in that frame | |
5d161b24 | 4427 | @end itemize |
c906108c SS |
4428 | |
4429 | @noindent This means that in the function | |
4430 | ||
4431 | @example | |
4432 | foo (a) | |
4433 | int a; | |
4434 | @{ | |
4435 | bar (a); | |
4436 | @{ | |
4437 | int b = test (); | |
4438 | bar (b); | |
4439 | @} | |
4440 | @} | |
4441 | @end example | |
4442 | ||
4443 | @noindent | |
4444 | you can examine and use the variable @code{a} whenever your program is | |
4445 | executing within the function @code{foo}, but you can only use or | |
4446 | examine the variable @code{b} while your program is executing inside | |
4447 | the block where @code{b} is declared. | |
4448 | ||
4449 | @cindex variable name conflict | |
4450 | There is an exception: you can refer to a variable or function whose | |
4451 | scope is a single source file even if the current execution point is not | |
4452 | in this file. But it is possible to have more than one such variable or | |
4453 | function with the same name (in different source files). If that | |
4454 | happens, referring to that name has unpredictable effects. If you wish, | |
4455 | you can specify a static variable in a particular function or file, | |
4456 | using the colon-colon notation: | |
4457 | ||
d4f3574e | 4458 | @cindex colon-colon, context for variables/functions |
c906108c SS |
4459 | @iftex |
4460 | @c info cannot cope with a :: index entry, but why deprive hard copy readers? | |
41afff9a | 4461 | @cindex @code{::}, context for variables/functions |
c906108c SS |
4462 | @end iftex |
4463 | @example | |
4464 | @var{file}::@var{variable} | |
4465 | @var{function}::@var{variable} | |
4466 | @end example | |
4467 | ||
4468 | @noindent | |
4469 | Here @var{file} or @var{function} is the name of the context for the | |
4470 | static @var{variable}. In the case of file names, you can use quotes to | |
4471 | make sure @value{GDBN} parses the file name as a single word---for example, | |
4472 | to print a global value of @code{x} defined in @file{f2.c}: | |
4473 | ||
4474 | @example | |
4475 | (@value{GDBP}) p 'f2.c'::x | |
4476 | @end example | |
4477 | ||
c906108c SS |
4478 | @cindex C++ scope resolution |
4479 | This use of @samp{::} is very rarely in conflict with the very similar | |
4480 | use of the same notation in C++. @value{GDBN} also supports use of the C++ | |
4481 | scope resolution operator in @value{GDBN} expressions. | |
4482 | @c FIXME: Um, so what happens in one of those rare cases where it's in | |
4483 | @c conflict?? --mew | |
c906108c SS |
4484 | |
4485 | @cindex wrong values | |
4486 | @cindex variable values, wrong | |
4487 | @quotation | |
4488 | @emph{Warning:} Occasionally, a local variable may appear to have the | |
4489 | wrong value at certain points in a function---just after entry to a new | |
4490 | scope, and just before exit. | |
4491 | @end quotation | |
4492 | You may see this problem when you are stepping by machine instructions. | |
4493 | This is because, on most machines, it takes more than one instruction to | |
4494 | set up a stack frame (including local variable definitions); if you are | |
4495 | stepping by machine instructions, variables may appear to have the wrong | |
4496 | values until the stack frame is completely built. On exit, it usually | |
4497 | also takes more than one machine instruction to destroy a stack frame; | |
4498 | after you begin stepping through that group of instructions, local | |
4499 | variable definitions may be gone. | |
4500 | ||
4501 | This may also happen when the compiler does significant optimizations. | |
4502 | To be sure of always seeing accurate values, turn off all optimization | |
4503 | when compiling. | |
4504 | ||
d4f3574e SS |
4505 | @cindex ``No symbol "foo" in current context'' |
4506 | Another possible effect of compiler optimizations is to optimize | |
4507 | unused variables out of existence, or assign variables to registers (as | |
4508 | opposed to memory addresses). Depending on the support for such cases | |
4509 | offered by the debug info format used by the compiler, @value{GDBN} | |
4510 | might not be able to display values for such local variables. If that | |
4511 | happens, @value{GDBN} will print a message like this: | |
4512 | ||
4513 | @example | |
4514 | No symbol "foo" in current context. | |
4515 | @end example | |
4516 | ||
4517 | To solve such problems, either recompile without optimizations, or use a | |
4518 | different debug info format, if the compiler supports several such | |
4519 | formats. For example, @value{NGCC}, the @sc{gnu} C/C++ compiler usually | |
4520 | supports the @samp{-gstabs} option. @samp{-gstabs} produces debug info | |
4521 | in a format that is superior to formats such as COFF. You may be able | |
96c405b3 | 4522 | to use DWARF2 (@samp{-gdwarf-2}), which is also an effective form for |
d4f3574e SS |
4523 | debug info. See @ref{Debugging Options,,Options for Debugging Your |
4524 | Program or @sc{gnu} CC, gcc.info, Using @sc{gnu} CC}, for more | |
4525 | information. | |
4526 | ||
4527 | ||
6d2ebf8b | 4528 | @node Arrays |
c906108c SS |
4529 | @section Artificial arrays |
4530 | ||
4531 | @cindex artificial array | |
41afff9a | 4532 | @kindex @@@r{, referencing memory as an array} |
c906108c SS |
4533 | It is often useful to print out several successive objects of the |
4534 | same type in memory; a section of an array, or an array of | |
4535 | dynamically determined size for which only a pointer exists in the | |
4536 | program. | |
4537 | ||
4538 | You can do this by referring to a contiguous span of memory as an | |
4539 | @dfn{artificial array}, using the binary operator @samp{@@}. The left | |
4540 | operand of @samp{@@} should be the first element of the desired array | |
4541 | and be an individual object. The right operand should be the desired length | |
4542 | of the array. The result is an array value whose elements are all of | |
4543 | the type of the left argument. The first element is actually the left | |
4544 | argument; the second element comes from bytes of memory immediately | |
4545 | following those that hold the first element, and so on. Here is an | |
4546 | example. If a program says | |
4547 | ||
4548 | @example | |
4549 | int *array = (int *) malloc (len * sizeof (int)); | |
4550 | @end example | |
4551 | ||
4552 | @noindent | |
4553 | you can print the contents of @code{array} with | |
4554 | ||
4555 | @example | |
4556 | p *array@@len | |
4557 | @end example | |
4558 | ||
4559 | The left operand of @samp{@@} must reside in memory. Array values made | |
4560 | with @samp{@@} in this way behave just like other arrays in terms of | |
4561 | subscripting, and are coerced to pointers when used in expressions. | |
4562 | Artificial arrays most often appear in expressions via the value history | |
4563 | (@pxref{Value History, ,Value history}), after printing one out. | |
4564 | ||
4565 | Another way to create an artificial array is to use a cast. | |
4566 | This re-interprets a value as if it were an array. | |
4567 | The value need not be in memory: | |
4568 | @example | |
4569 | (@value{GDBP}) p/x (short[2])0x12345678 | |
4570 | $1 = @{0x1234, 0x5678@} | |
4571 | @end example | |
4572 | ||
4573 | As a convenience, if you leave the array length out (as in | |
c3f6f71d | 4574 | @samp{(@var{type}[])@var{value}}) @value{GDBN} calculates the size to fill |
c906108c SS |
4575 | the value (as @samp{sizeof(@var{value})/sizeof(@var{type})}: |
4576 | @example | |
4577 | (@value{GDBP}) p/x (short[])0x12345678 | |
4578 | $2 = @{0x1234, 0x5678@} | |
4579 | @end example | |
4580 | ||
4581 | Sometimes the artificial array mechanism is not quite enough; in | |
4582 | moderately complex data structures, the elements of interest may not | |
4583 | actually be adjacent---for example, if you are interested in the values | |
4584 | of pointers in an array. One useful work-around in this situation is | |
4585 | to use a convenience variable (@pxref{Convenience Vars, ,Convenience | |
4586 | variables}) as a counter in an expression that prints the first | |
4587 | interesting value, and then repeat that expression via @key{RET}. For | |
4588 | instance, suppose you have an array @code{dtab} of pointers to | |
4589 | structures, and you are interested in the values of a field @code{fv} | |
4590 | in each structure. Here is an example of what you might type: | |
4591 | ||
4592 | @example | |
4593 | set $i = 0 | |
4594 | p dtab[$i++]->fv | |
4595 | @key{RET} | |
4596 | @key{RET} | |
4597 | @dots{} | |
4598 | @end example | |
4599 | ||
6d2ebf8b | 4600 | @node Output Formats |
c906108c SS |
4601 | @section Output formats |
4602 | ||
4603 | @cindex formatted output | |
4604 | @cindex output formats | |
4605 | By default, @value{GDBN} prints a value according to its data type. Sometimes | |
4606 | this is not what you want. For example, you might want to print a number | |
4607 | in hex, or a pointer in decimal. Or you might want to view data in memory | |
4608 | at a certain address as a character string or as an instruction. To do | |
4609 | these things, specify an @dfn{output format} when you print a value. | |
4610 | ||
4611 | The simplest use of output formats is to say how to print a value | |
4612 | already computed. This is done by starting the arguments of the | |
4613 | @code{print} command with a slash and a format letter. The format | |
4614 | letters supported are: | |
4615 | ||
4616 | @table @code | |
4617 | @item x | |
4618 | Regard the bits of the value as an integer, and print the integer in | |
4619 | hexadecimal. | |
4620 | ||
4621 | @item d | |
4622 | Print as integer in signed decimal. | |
4623 | ||
4624 | @item u | |
4625 | Print as integer in unsigned decimal. | |
4626 | ||
4627 | @item o | |
4628 | Print as integer in octal. | |
4629 | ||
4630 | @item t | |
4631 | Print as integer in binary. The letter @samp{t} stands for ``two''. | |
4632 | @footnote{@samp{b} cannot be used because these format letters are also | |
4633 | used with the @code{x} command, where @samp{b} stands for ``byte''; | |
d4f3574e | 4634 | see @ref{Memory,,Examining memory}.} |
c906108c SS |
4635 | |
4636 | @item a | |
4637 | @cindex unknown address, locating | |
4638 | Print as an address, both absolute in hexadecimal and as an offset from | |
4639 | the nearest preceding symbol. You can use this format used to discover | |
4640 | where (in what function) an unknown address is located: | |
4641 | ||
4642 | @example | |
4643 | (@value{GDBP}) p/a 0x54320 | |
4644 | $3 = 0x54320 <_initialize_vx+396> | |
4645 | @end example | |
4646 | ||
4647 | @item c | |
4648 | Regard as an integer and print it as a character constant. | |
4649 | ||
4650 | @item f | |
4651 | Regard the bits of the value as a floating point number and print | |
4652 | using typical floating point syntax. | |
4653 | @end table | |
4654 | ||
4655 | For example, to print the program counter in hex (@pxref{Registers}), type | |
4656 | ||
4657 | @example | |
4658 | p/x $pc | |
4659 | @end example | |
4660 | ||
4661 | @noindent | |
4662 | Note that no space is required before the slash; this is because command | |
4663 | names in @value{GDBN} cannot contain a slash. | |
4664 | ||
4665 | To reprint the last value in the value history with a different format, | |
4666 | you can use the @code{print} command with just a format and no | |
4667 | expression. For example, @samp{p/x} reprints the last value in hex. | |
4668 | ||
6d2ebf8b | 4669 | @node Memory |
c906108c SS |
4670 | @section Examining memory |
4671 | ||
4672 | You can use the command @code{x} (for ``examine'') to examine memory in | |
4673 | any of several formats, independently of your program's data types. | |
4674 | ||
4675 | @cindex examining memory | |
4676 | @table @code | |
41afff9a | 4677 | @kindex x @r{(examine memory)} |
c906108c SS |
4678 | @item x/@var{nfu} @var{addr} |
4679 | @itemx x @var{addr} | |
4680 | @itemx x | |
4681 | Use the @code{x} command to examine memory. | |
4682 | @end table | |
4683 | ||
4684 | @var{n}, @var{f}, and @var{u} are all optional parameters that specify how | |
4685 | much memory to display and how to format it; @var{addr} is an | |
4686 | expression giving the address where you want to start displaying memory. | |
4687 | If you use defaults for @var{nfu}, you need not type the slash @samp{/}. | |
4688 | Several commands set convenient defaults for @var{addr}. | |
4689 | ||
4690 | @table @r | |
4691 | @item @var{n}, the repeat count | |
4692 | The repeat count is a decimal integer; the default is 1. It specifies | |
4693 | how much memory (counting by units @var{u}) to display. | |
4694 | @c This really is **decimal**; unaffected by 'set radix' as of GDB | |
4695 | @c 4.1.2. | |
4696 | ||
4697 | @item @var{f}, the display format | |
4698 | The display format is one of the formats used by @code{print}, | |
4699 | @samp{s} (null-terminated string), or @samp{i} (machine instruction). | |
4700 | The default is @samp{x} (hexadecimal) initially. | |
4701 | The default changes each time you use either @code{x} or @code{print}. | |
4702 | ||
4703 | @item @var{u}, the unit size | |
4704 | The unit size is any of | |
4705 | ||
4706 | @table @code | |
4707 | @item b | |
4708 | Bytes. | |
4709 | @item h | |
4710 | Halfwords (two bytes). | |
4711 | @item w | |
4712 | Words (four bytes). This is the initial default. | |
4713 | @item g | |
4714 | Giant words (eight bytes). | |
4715 | @end table | |
4716 | ||
4717 | Each time you specify a unit size with @code{x}, that size becomes the | |
4718 | default unit the next time you use @code{x}. (For the @samp{s} and | |
4719 | @samp{i} formats, the unit size is ignored and is normally not written.) | |
4720 | ||
4721 | @item @var{addr}, starting display address | |
4722 | @var{addr} is the address where you want @value{GDBN} to begin displaying | |
4723 | memory. The expression need not have a pointer value (though it may); | |
4724 | it is always interpreted as an integer address of a byte of memory. | |
4725 | @xref{Expressions, ,Expressions}, for more information on expressions. The default for | |
4726 | @var{addr} is usually just after the last address examined---but several | |
4727 | other commands also set the default address: @code{info breakpoints} (to | |
4728 | the address of the last breakpoint listed), @code{info line} (to the | |
4729 | starting address of a line), and @code{print} (if you use it to display | |
4730 | a value from memory). | |
4731 | @end table | |
4732 | ||
4733 | For example, @samp{x/3uh 0x54320} is a request to display three halfwords | |
4734 | (@code{h}) of memory, formatted as unsigned decimal integers (@samp{u}), | |
4735 | starting at address @code{0x54320}. @samp{x/4xw $sp} prints the four | |
4736 | words (@samp{w}) of memory above the stack pointer (here, @samp{$sp}; | |
d4f3574e | 4737 | @pxref{Registers, ,Registers}) in hexadecimal (@samp{x}). |
c906108c SS |
4738 | |
4739 | Since the letters indicating unit sizes are all distinct from the | |
4740 | letters specifying output formats, you do not have to remember whether | |
4741 | unit size or format comes first; either order works. The output | |
4742 | specifications @samp{4xw} and @samp{4wx} mean exactly the same thing. | |
4743 | (However, the count @var{n} must come first; @samp{wx4} does not work.) | |
4744 | ||
4745 | Even though the unit size @var{u} is ignored for the formats @samp{s} | |
4746 | and @samp{i}, you might still want to use a count @var{n}; for example, | |
4747 | @samp{3i} specifies that you want to see three machine instructions, | |
4748 | including any operands. The command @code{disassemble} gives an | |
d4f3574e | 4749 | alternative way of inspecting machine instructions; see @ref{Machine |
c906108c SS |
4750 | Code,,Source and machine code}. |
4751 | ||
4752 | All the defaults for the arguments to @code{x} are designed to make it | |
4753 | easy to continue scanning memory with minimal specifications each time | |
4754 | you use @code{x}. For example, after you have inspected three machine | |
4755 | instructions with @samp{x/3i @var{addr}}, you can inspect the next seven | |
4756 | with just @samp{x/7}. If you use @key{RET} to repeat the @code{x} command, | |
4757 | the repeat count @var{n} is used again; the other arguments default as | |
4758 | for successive uses of @code{x}. | |
4759 | ||
4760 | @cindex @code{$_}, @code{$__}, and value history | |
4761 | The addresses and contents printed by the @code{x} command are not saved | |
4762 | in the value history because there is often too much of them and they | |
4763 | would get in the way. Instead, @value{GDBN} makes these values available for | |
4764 | subsequent use in expressions as values of the convenience variables | |
4765 | @code{$_} and @code{$__}. After an @code{x} command, the last address | |
4766 | examined is available for use in expressions in the convenience variable | |
4767 | @code{$_}. The contents of that address, as examined, are available in | |
4768 | the convenience variable @code{$__}. | |
4769 | ||
4770 | If the @code{x} command has a repeat count, the address and contents saved | |
4771 | are from the last memory unit printed; this is not the same as the last | |
4772 | address printed if several units were printed on the last line of output. | |
4773 | ||
6d2ebf8b | 4774 | @node Auto Display |
c906108c SS |
4775 | @section Automatic display |
4776 | @cindex automatic display | |
4777 | @cindex display of expressions | |
4778 | ||
4779 | If you find that you want to print the value of an expression frequently | |
4780 | (to see how it changes), you might want to add it to the @dfn{automatic | |
4781 | display list} so that @value{GDBN} prints its value each time your program stops. | |
4782 | Each expression added to the list is given a number to identify it; | |
4783 | to remove an expression from the list, you specify that number. | |
4784 | The automatic display looks like this: | |
4785 | ||
4786 | @example | |
4787 | 2: foo = 38 | |
4788 | 3: bar[5] = (struct hack *) 0x3804 | |
4789 | @end example | |
4790 | ||
4791 | @noindent | |
4792 | This display shows item numbers, expressions and their current values. As with | |
4793 | displays you request manually using @code{x} or @code{print}, you can | |
4794 | specify the output format you prefer; in fact, @code{display} decides | |
4795 | whether to use @code{print} or @code{x} depending on how elaborate your | |
4796 | format specification is---it uses @code{x} if you specify a unit size, | |
4797 | or one of the two formats (@samp{i} and @samp{s}) that are only | |
4798 | supported by @code{x}; otherwise it uses @code{print}. | |
4799 | ||
4800 | @table @code | |
4801 | @kindex display | |
d4f3574e SS |
4802 | @item display @var{expr} |
4803 | Add the expression @var{expr} to the list of expressions to display | |
c906108c SS |
4804 | each time your program stops. @xref{Expressions, ,Expressions}. |
4805 | ||
4806 | @code{display} does not repeat if you press @key{RET} again after using it. | |
4807 | ||
d4f3574e | 4808 | @item display/@var{fmt} @var{expr} |
c906108c | 4809 | For @var{fmt} specifying only a display format and not a size or |
d4f3574e | 4810 | count, add the expression @var{expr} to the auto-display list but |
c906108c SS |
4811 | arrange to display it each time in the specified format @var{fmt}. |
4812 | @xref{Output Formats,,Output formats}. | |
4813 | ||
4814 | @item display/@var{fmt} @var{addr} | |
4815 | For @var{fmt} @samp{i} or @samp{s}, or including a unit-size or a | |
4816 | number of units, add the expression @var{addr} as a memory address to | |
4817 | be examined each time your program stops. Examining means in effect | |
4818 | doing @samp{x/@var{fmt} @var{addr}}. @xref{Memory, ,Examining memory}. | |
4819 | @end table | |
4820 | ||
4821 | For example, @samp{display/i $pc} can be helpful, to see the machine | |
4822 | instruction about to be executed each time execution stops (@samp{$pc} | |
d4f3574e | 4823 | is a common name for the program counter; @pxref{Registers, ,Registers}). |
c906108c SS |
4824 | |
4825 | @table @code | |
4826 | @kindex delete display | |
4827 | @kindex undisplay | |
4828 | @item undisplay @var{dnums}@dots{} | |
4829 | @itemx delete display @var{dnums}@dots{} | |
4830 | Remove item numbers @var{dnums} from the list of expressions to display. | |
4831 | ||
4832 | @code{undisplay} does not repeat if you press @key{RET} after using it. | |
4833 | (Otherwise you would just get the error @samp{No display number @dots{}}.) | |
4834 | ||
4835 | @kindex disable display | |
4836 | @item disable display @var{dnums}@dots{} | |
4837 | Disable the display of item numbers @var{dnums}. A disabled display | |
4838 | item is not printed automatically, but is not forgotten. It may be | |
4839 | enabled again later. | |
4840 | ||
4841 | @kindex enable display | |
4842 | @item enable display @var{dnums}@dots{} | |
4843 | Enable display of item numbers @var{dnums}. It becomes effective once | |
4844 | again in auto display of its expression, until you specify otherwise. | |
4845 | ||
4846 | @item display | |
4847 | Display the current values of the expressions on the list, just as is | |
4848 | done when your program stops. | |
4849 | ||
4850 | @kindex info display | |
4851 | @item info display | |
4852 | Print the list of expressions previously set up to display | |
4853 | automatically, each one with its item number, but without showing the | |
4854 | values. This includes disabled expressions, which are marked as such. | |
4855 | It also includes expressions which would not be displayed right now | |
4856 | because they refer to automatic variables not currently available. | |
4857 | @end table | |
4858 | ||
4859 | If a display expression refers to local variables, then it does not make | |
4860 | sense outside the lexical context for which it was set up. Such an | |
4861 | expression is disabled when execution enters a context where one of its | |
4862 | variables is not defined. For example, if you give the command | |
4863 | @code{display last_char} while inside a function with an argument | |
4864 | @code{last_char}, @value{GDBN} displays this argument while your program | |
4865 | continues to stop inside that function. When it stops elsewhere---where | |
4866 | there is no variable @code{last_char}---the display is disabled | |
4867 | automatically. The next time your program stops where @code{last_char} | |
4868 | is meaningful, you can enable the display expression once again. | |
4869 | ||
6d2ebf8b | 4870 | @node Print Settings |
c906108c SS |
4871 | @section Print settings |
4872 | ||
4873 | @cindex format options | |
4874 | @cindex print settings | |
4875 | @value{GDBN} provides the following ways to control how arrays, structures, | |
4876 | and symbols are printed. | |
4877 | ||
4878 | @noindent | |
4879 | These settings are useful for debugging programs in any language: | |
4880 | ||
4881 | @table @code | |
4882 | @kindex set print address | |
4883 | @item set print address | |
4884 | @itemx set print address on | |
4885 | @value{GDBN} prints memory addresses showing the location of stack | |
4886 | traces, structure values, pointer values, breakpoints, and so forth, | |
4887 | even when it also displays the contents of those addresses. The default | |
4888 | is @code{on}. For example, this is what a stack frame display looks like with | |
4889 | @code{set print address on}: | |
4890 | ||
4891 | @smallexample | |
4892 | @group | |
4893 | (@value{GDBP}) f | |
4894 | #0 set_quotes (lq=0x34c78 "<<", rq=0x34c88 ">>") | |
4895 | at input.c:530 | |
4896 | 530 if (lquote != def_lquote) | |
4897 | @end group | |
4898 | @end smallexample | |
4899 | ||
4900 | @item set print address off | |
4901 | Do not print addresses when displaying their contents. For example, | |
4902 | this is the same stack frame displayed with @code{set print address off}: | |
4903 | ||
4904 | @smallexample | |
4905 | @group | |
4906 | (@value{GDBP}) set print addr off | |
4907 | (@value{GDBP}) f | |
4908 | #0 set_quotes (lq="<<", rq=">>") at input.c:530 | |
4909 | 530 if (lquote != def_lquote) | |
4910 | @end group | |
4911 | @end smallexample | |
4912 | ||
4913 | You can use @samp{set print address off} to eliminate all machine | |
4914 | dependent displays from the @value{GDBN} interface. For example, with | |
4915 | @code{print address off}, you should get the same text for backtraces on | |
4916 | all machines---whether or not they involve pointer arguments. | |
4917 | ||
4918 | @kindex show print address | |
4919 | @item show print address | |
4920 | Show whether or not addresses are to be printed. | |
4921 | @end table | |
4922 | ||
4923 | When @value{GDBN} prints a symbolic address, it normally prints the | |
4924 | closest earlier symbol plus an offset. If that symbol does not uniquely | |
4925 | identify the address (for example, it is a name whose scope is a single | |
4926 | source file), you may need to clarify. One way to do this is with | |
4927 | @code{info line}, for example @samp{info line *0x4537}. Alternately, | |
4928 | you can set @value{GDBN} to print the source file and line number when | |
4929 | it prints a symbolic address: | |
4930 | ||
4931 | @table @code | |
4932 | @kindex set print symbol-filename | |
4933 | @item set print symbol-filename on | |
4934 | Tell @value{GDBN} to print the source file name and line number of a | |
4935 | symbol in the symbolic form of an address. | |
4936 | ||
4937 | @item set print symbol-filename off | |
4938 | Do not print source file name and line number of a symbol. This is the | |
4939 | default. | |
4940 | ||
4941 | @kindex show print symbol-filename | |
4942 | @item show print symbol-filename | |
4943 | Show whether or not @value{GDBN} will print the source file name and | |
4944 | line number of a symbol in the symbolic form of an address. | |
4945 | @end table | |
4946 | ||
4947 | Another situation where it is helpful to show symbol filenames and line | |
4948 | numbers is when disassembling code; @value{GDBN} shows you the line | |
4949 | number and source file that corresponds to each instruction. | |
4950 | ||
4951 | Also, you may wish to see the symbolic form only if the address being | |
4952 | printed is reasonably close to the closest earlier symbol: | |
4953 | ||
4954 | @table @code | |
4955 | @kindex set print max-symbolic-offset | |
4956 | @item set print max-symbolic-offset @var{max-offset} | |
4957 | Tell @value{GDBN} to only display the symbolic form of an address if the | |
4958 | offset between the closest earlier symbol and the address is less than | |
5d161b24 | 4959 | @var{max-offset}. The default is 0, which tells @value{GDBN} |
c906108c SS |
4960 | to always print the symbolic form of an address if any symbol precedes it. |
4961 | ||
4962 | @kindex show print max-symbolic-offset | |
4963 | @item show print max-symbolic-offset | |
4964 | Ask how large the maximum offset is that @value{GDBN} prints in a | |
4965 | symbolic address. | |
4966 | @end table | |
4967 | ||
4968 | @cindex wild pointer, interpreting | |
4969 | @cindex pointer, finding referent | |
4970 | If you have a pointer and you are not sure where it points, try | |
4971 | @samp{set print symbol-filename on}. Then you can determine the name | |
4972 | and source file location of the variable where it points, using | |
4973 | @samp{p/a @var{pointer}}. This interprets the address in symbolic form. | |
4974 | For example, here @value{GDBN} shows that a variable @code{ptt} points | |
4975 | at another variable @code{t}, defined in @file{hi2.c}: | |
4976 | ||
4977 | @example | |
4978 | (@value{GDBP}) set print symbol-filename on | |
4979 | (@value{GDBP}) p/a ptt | |
4980 | $4 = 0xe008 <t in hi2.c> | |
4981 | @end example | |
4982 | ||
4983 | @quotation | |
4984 | @emph{Warning:} For pointers that point to a local variable, @samp{p/a} | |
4985 | does not show the symbol name and filename of the referent, even with | |
4986 | the appropriate @code{set print} options turned on. | |
4987 | @end quotation | |
4988 | ||
4989 | Other settings control how different kinds of objects are printed: | |
4990 | ||
4991 | @table @code | |
4992 | @kindex set print array | |
4993 | @item set print array | |
4994 | @itemx set print array on | |
4995 | Pretty print arrays. This format is more convenient to read, | |
4996 | but uses more space. The default is off. | |
4997 | ||
4998 | @item set print array off | |
4999 | Return to compressed format for arrays. | |
5000 | ||
5001 | @kindex show print array | |
5002 | @item show print array | |
5003 | Show whether compressed or pretty format is selected for displaying | |
5004 | arrays. | |
5005 | ||
5006 | @kindex set print elements | |
5007 | @item set print elements @var{number-of-elements} | |
5008 | Set a limit on how many elements of an array @value{GDBN} will print. | |
5009 | If @value{GDBN} is printing a large array, it stops printing after it has | |
5010 | printed the number of elements set by the @code{set print elements} command. | |
5011 | This limit also applies to the display of strings. | |
d4f3574e | 5012 | When @value{GDBN} starts, this limit is set to 200. |
c906108c SS |
5013 | Setting @var{number-of-elements} to zero means that the printing is unlimited. |
5014 | ||
5015 | @kindex show print elements | |
5016 | @item show print elements | |
5017 | Display the number of elements of a large array that @value{GDBN} will print. | |
5018 | If the number is 0, then the printing is unlimited. | |
5019 | ||
5020 | @kindex set print null-stop | |
5021 | @item set print null-stop | |
5022 | Cause @value{GDBN} to stop printing the characters of an array when the first | |
d4f3574e | 5023 | @sc{null} is encountered. This is useful when large arrays actually |
c906108c | 5024 | contain only short strings. |
d4f3574e | 5025 | The default is off. |
c906108c SS |
5026 | |
5027 | @kindex set print pretty | |
5028 | @item set print pretty on | |
5d161b24 | 5029 | Cause @value{GDBN} to print structures in an indented format with one member |
c906108c SS |
5030 | per line, like this: |
5031 | ||
5032 | @smallexample | |
5033 | @group | |
5034 | $1 = @{ | |
5035 | next = 0x0, | |
5036 | flags = @{ | |
5037 | sweet = 1, | |
5038 | sour = 1 | |
5039 | @}, | |
5040 | meat = 0x54 "Pork" | |
5041 | @} | |
5042 | @end group | |
5043 | @end smallexample | |
5044 | ||
5045 | @item set print pretty off | |
5046 | Cause @value{GDBN} to print structures in a compact format, like this: | |
5047 | ||
5048 | @smallexample | |
5049 | @group | |
5050 | $1 = @{next = 0x0, flags = @{sweet = 1, sour = 1@}, \ | |
5051 | meat = 0x54 "Pork"@} | |
5052 | @end group | |
5053 | @end smallexample | |
5054 | ||
5055 | @noindent | |
5056 | This is the default format. | |
5057 | ||
5058 | @kindex show print pretty | |
5059 | @item show print pretty | |
5060 | Show which format @value{GDBN} is using to print structures. | |
5061 | ||
5062 | @kindex set print sevenbit-strings | |
5063 | @item set print sevenbit-strings on | |
5064 | Print using only seven-bit characters; if this option is set, | |
5065 | @value{GDBN} displays any eight-bit characters (in strings or | |
5066 | character values) using the notation @code{\}@var{nnn}. This setting is | |
5067 | best if you are working in English (@sc{ascii}) and you use the | |
5068 | high-order bit of characters as a marker or ``meta'' bit. | |
5069 | ||
5070 | @item set print sevenbit-strings off | |
5071 | Print full eight-bit characters. This allows the use of more | |
5072 | international character sets, and is the default. | |
5073 | ||
5074 | @kindex show print sevenbit-strings | |
5075 | @item show print sevenbit-strings | |
5076 | Show whether or not @value{GDBN} is printing only seven-bit characters. | |
5077 | ||
5078 | @kindex set print union | |
5079 | @item set print union on | |
5d161b24 | 5080 | Tell @value{GDBN} to print unions which are contained in structures. This |
c906108c SS |
5081 | is the default setting. |
5082 | ||
5083 | @item set print union off | |
5084 | Tell @value{GDBN} not to print unions which are contained in structures. | |
5085 | ||
5086 | @kindex show print union | |
5087 | @item show print union | |
5088 | Ask @value{GDBN} whether or not it will print unions which are contained in | |
5089 | structures. | |
5090 | ||
5091 | For example, given the declarations | |
5092 | ||
5093 | @smallexample | |
5094 | typedef enum @{Tree, Bug@} Species; | |
5095 | typedef enum @{Big_tree, Acorn, Seedling@} Tree_forms; | |
5d161b24 | 5096 | typedef enum @{Caterpillar, Cocoon, Butterfly@} |
c906108c SS |
5097 | Bug_forms; |
5098 | ||
5099 | struct thing @{ | |
5100 | Species it; | |
5101 | union @{ | |
5102 | Tree_forms tree; | |
5103 | Bug_forms bug; | |
5104 | @} form; | |
5105 | @}; | |
5106 | ||
5107 | struct thing foo = @{Tree, @{Acorn@}@}; | |
5108 | @end smallexample | |
5109 | ||
5110 | @noindent | |
5111 | with @code{set print union on} in effect @samp{p foo} would print | |
5112 | ||
5113 | @smallexample | |
5114 | $1 = @{it = Tree, form = @{tree = Acorn, bug = Cocoon@}@} | |
5115 | @end smallexample | |
5116 | ||
5117 | @noindent | |
5118 | and with @code{set print union off} in effect it would print | |
5119 | ||
5120 | @smallexample | |
5121 | $1 = @{it = Tree, form = @{...@}@} | |
5122 | @end smallexample | |
5123 | @end table | |
5124 | ||
c906108c SS |
5125 | @need 1000 |
5126 | @noindent | |
5127 | These settings are of interest when debugging C++ programs: | |
5128 | ||
5129 | @table @code | |
5130 | @cindex demangling | |
5131 | @kindex set print demangle | |
5132 | @item set print demangle | |
5133 | @itemx set print demangle on | |
5134 | Print C++ names in their source form rather than in the encoded | |
5135 | (``mangled'') form passed to the assembler and linker for type-safe | |
d4f3574e | 5136 | linkage. The default is on. |
c906108c SS |
5137 | |
5138 | @kindex show print demangle | |
5139 | @item show print demangle | |
5140 | Show whether C++ names are printed in mangled or demangled form. | |
5141 | ||
5142 | @kindex set print asm-demangle | |
5143 | @item set print asm-demangle | |
5144 | @itemx set print asm-demangle on | |
5145 | Print C++ names in their source form rather than their mangled form, even | |
5146 | in assembler code printouts such as instruction disassemblies. | |
5147 | The default is off. | |
5148 | ||
5149 | @kindex show print asm-demangle | |
5150 | @item show print asm-demangle | |
5151 | Show whether C++ names in assembly listings are printed in mangled | |
5152 | or demangled form. | |
5153 | ||
5154 | @kindex set demangle-style | |
5155 | @cindex C++ symbol decoding style | |
5156 | @cindex symbol decoding style, C++ | |
5157 | @item set demangle-style @var{style} | |
5158 | Choose among several encoding schemes used by different compilers to | |
5159 | represent C++ names. The choices for @var{style} are currently: | |
5160 | ||
5161 | @table @code | |
5162 | @item auto | |
5163 | Allow @value{GDBN} to choose a decoding style by inspecting your program. | |
5164 | ||
5165 | @item gnu | |
5d161b24 | 5166 | Decode based on the @sc{gnu} C++ compiler (@code{g++}) encoding algorithm. |
c906108c | 5167 | This is the default. |
c906108c SS |
5168 | |
5169 | @item hp | |
5170 | Decode based on the HP ANSI C++ (@code{aCC}) encoding algorithm. | |
5171 | ||
5172 | @item lucid | |
5173 | Decode based on the Lucid C++ compiler (@code{lcc}) encoding algorithm. | |
5174 | ||
5175 | @item arm | |
5176 | Decode using the algorithm in the @cite{C++ Annotated Reference Manual}. | |
5177 | @strong{Warning:} this setting alone is not sufficient to allow | |
5178 | debugging @code{cfront}-generated executables. @value{GDBN} would | |
5179 | require further enhancement to permit that. | |
5180 | ||
5181 | @end table | |
5182 | If you omit @var{style}, you will see a list of possible formats. | |
5183 | ||
5184 | @kindex show demangle-style | |
5185 | @item show demangle-style | |
5186 | Display the encoding style currently in use for decoding C++ symbols. | |
5187 | ||
5188 | @kindex set print object | |
5189 | @item set print object | |
5190 | @itemx set print object on | |
5191 | When displaying a pointer to an object, identify the @emph{actual} | |
5192 | (derived) type of the object rather than the @emph{declared} type, using | |
5193 | the virtual function table. | |
5194 | ||
5195 | @item set print object off | |
5196 | Display only the declared type of objects, without reference to the | |
5197 | virtual function table. This is the default setting. | |
5198 | ||
5199 | @kindex show print object | |
5200 | @item show print object | |
5201 | Show whether actual, or declared, object types are displayed. | |
5202 | ||
5203 | @kindex set print static-members | |
5204 | @item set print static-members | |
5205 | @itemx set print static-members on | |
5206 | Print static members when displaying a C++ object. The default is on. | |
5207 | ||
5208 | @item set print static-members off | |
5209 | Do not print static members when displaying a C++ object. | |
5210 | ||
5211 | @kindex show print static-members | |
5212 | @item show print static-members | |
5213 | Show whether C++ static members are printed, or not. | |
5214 | ||
5215 | @c These don't work with HP ANSI C++ yet. | |
5216 | @kindex set print vtbl | |
5217 | @item set print vtbl | |
5218 | @itemx set print vtbl on | |
5219 | Pretty print C++ virtual function tables. The default is off. | |
c906108c SS |
5220 | (The @code{vtbl} commands do not work on programs compiled with the HP |
5221 | ANSI C++ compiler (@code{aCC}).) | |
c906108c SS |
5222 | |
5223 | @item set print vtbl off | |
5224 | Do not pretty print C++ virtual function tables. | |
5225 | ||
5226 | @kindex show print vtbl | |
5227 | @item show print vtbl | |
5228 | Show whether C++ virtual function tables are pretty printed, or not. | |
5229 | @end table | |
c906108c | 5230 | |
6d2ebf8b | 5231 | @node Value History |
c906108c SS |
5232 | @section Value history |
5233 | ||
5234 | @cindex value history | |
5d161b24 DB |
5235 | Values printed by the @code{print} command are saved in the @value{GDBN} |
5236 | @dfn{value history}. This allows you to refer to them in other expressions. | |
5237 | Values are kept until the symbol table is re-read or discarded | |
5238 | (for example with the @code{file} or @code{symbol-file} commands). | |
5239 | When the symbol table changes, the value history is discarded, | |
5240 | since the values may contain pointers back to the types defined in the | |
c906108c SS |
5241 | symbol table. |
5242 | ||
5243 | @cindex @code{$} | |
5244 | @cindex @code{$$} | |
5245 | @cindex history number | |
5246 | The values printed are given @dfn{history numbers} by which you can | |
5247 | refer to them. These are successive integers starting with one. | |
5248 | @code{print} shows you the history number assigned to a value by | |
5249 | printing @samp{$@var{num} = } before the value; here @var{num} is the | |
5250 | history number. | |
5251 | ||
5252 | To refer to any previous value, use @samp{$} followed by the value's | |
5253 | history number. The way @code{print} labels its output is designed to | |
5254 | remind you of this. Just @code{$} refers to the most recent value in | |
5255 | the history, and @code{$$} refers to the value before that. | |
5256 | @code{$$@var{n}} refers to the @var{n}th value from the end; @code{$$2} | |
5257 | is the value just prior to @code{$$}, @code{$$1} is equivalent to | |
5258 | @code{$$}, and @code{$$0} is equivalent to @code{$}. | |
5259 | ||
5260 | For example, suppose you have just printed a pointer to a structure and | |
5261 | want to see the contents of the structure. It suffices to type | |
5262 | ||
5263 | @example | |
5264 | p *$ | |
5265 | @end example | |
5266 | ||
5267 | If you have a chain of structures where the component @code{next} points | |
5268 | to the next one, you can print the contents of the next one with this: | |
5269 | ||
5270 | @example | |
5271 | p *$.next | |
5272 | @end example | |
5273 | ||
5274 | @noindent | |
5275 | You can print successive links in the chain by repeating this | |
5276 | command---which you can do by just typing @key{RET}. | |
5277 | ||
5278 | Note that the history records values, not expressions. If the value of | |
5279 | @code{x} is 4 and you type these commands: | |
5280 | ||
5281 | @example | |
5282 | print x | |
5283 | set x=5 | |
5284 | @end example | |
5285 | ||
5286 | @noindent | |
5287 | then the value recorded in the value history by the @code{print} command | |
5288 | remains 4 even though the value of @code{x} has changed. | |
5289 | ||
5290 | @table @code | |
5291 | @kindex show values | |
5292 | @item show values | |
5293 | Print the last ten values in the value history, with their item numbers. | |
5294 | This is like @samp{p@ $$9} repeated ten times, except that @code{show | |
5295 | values} does not change the history. | |
5296 | ||
5297 | @item show values @var{n} | |
5298 | Print ten history values centered on history item number @var{n}. | |
5299 | ||
5300 | @item show values + | |
5301 | Print ten history values just after the values last printed. If no more | |
5302 | values are available, @code{show values +} produces no display. | |
5303 | @end table | |
5304 | ||
5305 | Pressing @key{RET} to repeat @code{show values @var{n}} has exactly the | |
5306 | same effect as @samp{show values +}. | |
5307 | ||
6d2ebf8b | 5308 | @node Convenience Vars |
c906108c SS |
5309 | @section Convenience variables |
5310 | ||
5311 | @cindex convenience variables | |
5312 | @value{GDBN} provides @dfn{convenience variables} that you can use within | |
5313 | @value{GDBN} to hold on to a value and refer to it later. These variables | |
5314 | exist entirely within @value{GDBN}; they are not part of your program, and | |
5315 | setting a convenience variable has no direct effect on further execution | |
5316 | of your program. That is why you can use them freely. | |
5317 | ||
5318 | Convenience variables are prefixed with @samp{$}. Any name preceded by | |
5319 | @samp{$} can be used for a convenience variable, unless it is one of | |
d4f3574e | 5320 | the predefined machine-specific register names (@pxref{Registers, ,Registers}). |
c906108c SS |
5321 | (Value history references, in contrast, are @emph{numbers} preceded |
5322 | by @samp{$}. @xref{Value History, ,Value history}.) | |
5323 | ||
5324 | You can save a value in a convenience variable with an assignment | |
5325 | expression, just as you would set a variable in your program. | |
5326 | For example: | |
5327 | ||
5328 | @example | |
5329 | set $foo = *object_ptr | |
5330 | @end example | |
5331 | ||
5332 | @noindent | |
5333 | would save in @code{$foo} the value contained in the object pointed to by | |
5334 | @code{object_ptr}. | |
5335 | ||
5336 | Using a convenience variable for the first time creates it, but its | |
5337 | value is @code{void} until you assign a new value. You can alter the | |
5338 | value with another assignment at any time. | |
5339 | ||
5340 | Convenience variables have no fixed types. You can assign a convenience | |
5341 | variable any type of value, including structures and arrays, even if | |
5342 | that variable already has a value of a different type. The convenience | |
5343 | variable, when used as an expression, has the type of its current value. | |
5344 | ||
5345 | @table @code | |
5346 | @kindex show convenience | |
5347 | @item show convenience | |
5348 | Print a list of convenience variables used so far, and their values. | |
d4f3574e | 5349 | Abbreviated @code{show conv}. |
c906108c SS |
5350 | @end table |
5351 | ||
5352 | One of the ways to use a convenience variable is as a counter to be | |
5353 | incremented or a pointer to be advanced. For example, to print | |
5354 | a field from successive elements of an array of structures: | |
5355 | ||
5356 | @example | |
5357 | set $i = 0 | |
5358 | print bar[$i++]->contents | |
5359 | @end example | |
5360 | ||
d4f3574e SS |
5361 | @noindent |
5362 | Repeat that command by typing @key{RET}. | |
c906108c SS |
5363 | |
5364 | Some convenience variables are created automatically by @value{GDBN} and given | |
5365 | values likely to be useful. | |
5366 | ||
5367 | @table @code | |
41afff9a | 5368 | @vindex $_@r{, convenience variable} |
c906108c SS |
5369 | @item $_ |
5370 | The variable @code{$_} is automatically set by the @code{x} command to | |
5371 | the last address examined (@pxref{Memory, ,Examining memory}). Other | |
5372 | commands which provide a default address for @code{x} to examine also | |
5373 | set @code{$_} to that address; these commands include @code{info line} | |
5374 | and @code{info breakpoint}. The type of @code{$_} is @code{void *} | |
5375 | except when set by the @code{x} command, in which case it is a pointer | |
5376 | to the type of @code{$__}. | |
5377 | ||
41afff9a | 5378 | @vindex $__@r{, convenience variable} |
c906108c SS |
5379 | @item $__ |
5380 | The variable @code{$__} is automatically set by the @code{x} command | |
5381 | to the value found in the last address examined. Its type is chosen | |
5382 | to match the format in which the data was printed. | |
5383 | ||
5384 | @item $_exitcode | |
41afff9a | 5385 | @vindex $_exitcode@r{, convenience variable} |
c906108c SS |
5386 | The variable @code{$_exitcode} is automatically set to the exit code when |
5387 | the program being debugged terminates. | |
5388 | @end table | |
5389 | ||
53a5351d JM |
5390 | On HP-UX systems, if you refer to a function or variable name that |
5391 | begins with a dollar sign, @value{GDBN} searches for a user or system | |
5392 | name first, before it searches for a convenience variable. | |
c906108c | 5393 | |
6d2ebf8b | 5394 | @node Registers |
c906108c SS |
5395 | @section Registers |
5396 | ||
5397 | @cindex registers | |
5398 | You can refer to machine register contents, in expressions, as variables | |
5399 | with names starting with @samp{$}. The names of registers are different | |
5400 | for each machine; use @code{info registers} to see the names used on | |
5401 | your machine. | |
5402 | ||
5403 | @table @code | |
5404 | @kindex info registers | |
5405 | @item info registers | |
5406 | Print the names and values of all registers except floating-point | |
5407 | registers (in the selected stack frame). | |
5408 | ||
5409 | @kindex info all-registers | |
5410 | @cindex floating point registers | |
5411 | @item info all-registers | |
5412 | Print the names and values of all registers, including floating-point | |
5413 | registers. | |
5414 | ||
5415 | @item info registers @var{regname} @dots{} | |
5416 | Print the @dfn{relativized} value of each specified register @var{regname}. | |
5d161b24 DB |
5417 | As discussed in detail below, register values are normally relative to |
5418 | the selected stack frame. @var{regname} may be any register name valid on | |
c906108c SS |
5419 | the machine you are using, with or without the initial @samp{$}. |
5420 | @end table | |
5421 | ||
5422 | @value{GDBN} has four ``standard'' register names that are available (in | |
5423 | expressions) on most machines---whenever they do not conflict with an | |
5424 | architecture's canonical mnemonics for registers. The register names | |
5425 | @code{$pc} and @code{$sp} are used for the program counter register and | |
5426 | the stack pointer. @code{$fp} is used for a register that contains a | |
5427 | pointer to the current stack frame, and @code{$ps} is used for a | |
5428 | register that contains the processor status. For example, | |
5429 | you could print the program counter in hex with | |
5430 | ||
5431 | @example | |
5432 | p/x $pc | |
5433 | @end example | |
5434 | ||
5435 | @noindent | |
5436 | or print the instruction to be executed next with | |
5437 | ||
5438 | @example | |
5439 | x/i $pc | |
5440 | @end example | |
5441 | ||
5442 | @noindent | |
5443 | or add four to the stack pointer@footnote{This is a way of removing | |
5444 | one word from the stack, on machines where stacks grow downward in | |
5445 | memory (most machines, nowadays). This assumes that the innermost | |
5446 | stack frame is selected; setting @code{$sp} is not allowed when other | |
5447 | stack frames are selected. To pop entire frames off the stack, | |
5448 | regardless of machine architecture, use @code{return}; | |
d4f3574e | 5449 | see @ref{Returning, ,Returning from a function}.} with |
c906108c SS |
5450 | |
5451 | @example | |
5452 | set $sp += 4 | |
5453 | @end example | |
5454 | ||
5455 | Whenever possible, these four standard register names are available on | |
5456 | your machine even though the machine has different canonical mnemonics, | |
5457 | so long as there is no conflict. The @code{info registers} command | |
5458 | shows the canonical names. For example, on the SPARC, @code{info | |
5459 | registers} displays the processor status register as @code{$psr} but you | |
d4f3574e SS |
5460 | can also refer to it as @code{$ps}; and on x86-based machines @code{$ps} |
5461 | is an alias for the @sc{eflags} register. | |
c906108c SS |
5462 | |
5463 | @value{GDBN} always considers the contents of an ordinary register as an | |
5464 | integer when the register is examined in this way. Some machines have | |
5465 | special registers which can hold nothing but floating point; these | |
5466 | registers are considered to have floating point values. There is no way | |
5467 | to refer to the contents of an ordinary register as floating point value | |
5468 | (although you can @emph{print} it as a floating point value with | |
5469 | @samp{print/f $@var{regname}}). | |
5470 | ||
5471 | Some registers have distinct ``raw'' and ``virtual'' data formats. This | |
5472 | means that the data format in which the register contents are saved by | |
5473 | the operating system is not the same one that your program normally | |
5474 | sees. For example, the registers of the 68881 floating point | |
5475 | coprocessor are always saved in ``extended'' (raw) format, but all C | |
5476 | programs expect to work with ``double'' (virtual) format. In such | |
5d161b24 | 5477 | cases, @value{GDBN} normally works with the virtual format only (the format |
c906108c SS |
5478 | that makes sense for your program), but the @code{info registers} command |
5479 | prints the data in both formats. | |
5480 | ||
5481 | Normally, register values are relative to the selected stack frame | |
5482 | (@pxref{Selection, ,Selecting a frame}). This means that you get the | |
5483 | value that the register would contain if all stack frames farther in | |
5484 | were exited and their saved registers restored. In order to see the | |
5485 | true contents of hardware registers, you must select the innermost | |
5486 | frame (with @samp{frame 0}). | |
5487 | ||
5488 | However, @value{GDBN} must deduce where registers are saved, from the machine | |
5489 | code generated by your compiler. If some registers are not saved, or if | |
5490 | @value{GDBN} is unable to locate the saved registers, the selected stack | |
5491 | frame makes no difference. | |
5492 | ||
6d2ebf8b | 5493 | @node Floating Point Hardware |
c906108c SS |
5494 | @section Floating point hardware |
5495 | @cindex floating point | |
5496 | ||
5497 | Depending on the configuration, @value{GDBN} may be able to give | |
5498 | you more information about the status of the floating point hardware. | |
5499 | ||
5500 | @table @code | |
5501 | @kindex info float | |
5502 | @item info float | |
5503 | Display hardware-dependent information about the floating | |
5504 | point unit. The exact contents and layout vary depending on the | |
5505 | floating point chip. Currently, @samp{info float} is supported on | |
5506 | the ARM and x86 machines. | |
5507 | @end table | |
c906108c | 5508 | |
29e57380 C |
5509 | @node Memory Region Attributes |
5510 | @section Memory Region Attributes | |
5511 | @cindex memory region attributes | |
5512 | ||
5513 | @dfn{Memory region attributes} allow you to describe special handling | |
5514 | required by regions of your target's memory. @value{GDBN} uses attributes | |
5515 | to determine whether to allow certain types of memory accesses; whether to | |
5516 | use specific width accesses; and whether to cache target memory. | |
5517 | ||
5518 | Defined memory regions can be individually enabled and disabled. When a | |
5519 | memory region is disabled, @value{GDBN} uses the default attributes when | |
5520 | accessing memory in that region. Similarly, if no memory regions have | |
5521 | been defined, @value{GDBN} uses the default attributes when accessing | |
5522 | all memory. | |
5523 | ||
5524 | When a memory region is defined, it is given a number to identify it; | |
5525 | to enable, disable, or remove a memory region, you specify that number. | |
5526 | ||
5527 | @table @code | |
5528 | @kindex mem | |
5529 | @item mem @var{address1} @var{address1} @var{attributes}@dots{} | |
5530 | Define memory region bounded by @var{address1} and @var{address2} | |
5531 | with attributes @var{attributes}@dots{}. | |
5532 | ||
5533 | @kindex delete mem | |
5534 | @item delete mem @var{nums}@dots{} | |
5535 | Remove memory region numbers @var{nums}. | |
5536 | ||
5537 | @kindex disable mem | |
5538 | @item disable mem @var{nums}@dots{} | |
5539 | Disable memory region numbers @var{nums}. | |
5540 | A disabled memory region is not forgotten. | |
5541 | It may be enabled again later. | |
5542 | ||
5543 | @kindex enable mem | |
5544 | @item enable mem @var{nums}@dots{} | |
5545 | Enable memory region numbers @var{nums}. | |
5546 | ||
5547 | @kindex info mem | |
5548 | @item info mem | |
5549 | Print a table of all defined memory regions, with the following columns | |
5550 | for each region. | |
5551 | ||
5552 | @table @emph | |
5553 | @item Memory Region Number | |
5554 | @item Enabled or Disabled. | |
5555 | Enabled memory regions are marked with @samp{y}. | |
5556 | Disabled memory regions are marked with @samp{n}. | |
5557 | ||
5558 | @item Lo Address | |
5559 | The address defining the inclusive lower bound of the memory region. | |
5560 | ||
5561 | @item Hi Address | |
5562 | The address defining the exclusive upper bound of the memory region. | |
5563 | ||
5564 | @item Attributes | |
5565 | The list of attributes set for this memory region. | |
5566 | @end table | |
5567 | @end table | |
5568 | ||
5569 | ||
5570 | @subsection Attributes | |
5571 | ||
5572 | @subsubsection Memory Access Mode | |
5573 | The access mode attributes set whether @value{GDBN} may make read or | |
5574 | write accesses to a memory region. | |
5575 | ||
5576 | While these attributes prevent @value{GDBN} from performing invalid | |
5577 | memory accesses, they do nothing to prevent the target system, I/O DMA, | |
5578 | etc. from accessing memory. | |
5579 | ||
5580 | @table @code | |
5581 | @item ro | |
5582 | Memory is read only. | |
5583 | @item wo | |
5584 | Memory is write only. | |
5585 | @item rw | |
5586 | Memory is read/write (default). | |
5587 | @end table | |
5588 | ||
5589 | @subsubsection Memory Access Size | |
5590 | The acccess size attributes tells @value{GDBN} to use specific sized | |
5591 | accesses in the memory region. Often memory mapped device registers | |
5592 | require specific sized accesses. If no access size attribute is | |
5593 | specified, @value{GDBN} may use accesses of any size. | |
5594 | ||
5595 | @table @code | |
5596 | @item 8 | |
5597 | Use 8 bit memory accesses. | |
5598 | @item 16 | |
5599 | Use 16 bit memory accesses. | |
5600 | @item 32 | |
5601 | Use 32 bit memory accesses. | |
5602 | @item 64 | |
5603 | Use 64 bit memory accesses. | |
5604 | @end table | |
5605 | ||
5606 | @c @subsubsection Hardware/Software Breakpoints | |
5607 | @c The hardware/software breakpoint attributes set whether @value{GDBN} | |
5608 | @c will use hardware or software breakpoints for the internal breakpoints | |
5609 | @c used by the step, next, finish, until, etc. commands. | |
5610 | @c | |
5611 | @c @table @code | |
5612 | @c @item hwbreak | |
5613 | @c Always use hardware breakpoints | |
5614 | @c @item swbreak (default) | |
5615 | @c @end table | |
5616 | ||
5617 | @subsubsection Data Cache | |
5618 | The data cache attributes set whether @value{GDBN} will cache target | |
5619 | memory. While this generally improves performance by reducing debug | |
5620 | protocol overhead, it can lead to incorrect results because @value{GDBN} | |
5621 | does not know about volatile variables or memory mapped device | |
5622 | registers. | |
5623 | ||
5624 | @table @code | |
5625 | @item cache | |
5626 | Enable @value{GDBN} to cache target memory. | |
5627 | @item nocache (default) | |
5628 | Disable @value{GDBN} from caching target memory. | |
5629 | @end table | |
5630 | ||
5631 | @c @subsubsection Memory Write Verification | |
5632 | @c The memory write verification attributes set whether @value{GDBN} | |
5633 | @c will re-reads data after each write to verify the write was successful. | |
5634 | @c | |
5635 | @c @table @code | |
5636 | @c @item verify | |
5637 | @c @item noverify (default) | |
5638 | @c @end table | |
5639 | ||
6d2ebf8b | 5640 | @node Languages |
c906108c SS |
5641 | @chapter Using @value{GDBN} with Different Languages |
5642 | @cindex languages | |
5643 | ||
c906108c SS |
5644 | Although programming languages generally have common aspects, they are |
5645 | rarely expressed in the same manner. For instance, in ANSI C, | |
5646 | dereferencing a pointer @code{p} is accomplished by @code{*p}, but in | |
5647 | Modula-2, it is accomplished by @code{p^}. Values can also be | |
5d161b24 | 5648 | represented (and displayed) differently. Hex numbers in C appear as |
c906108c | 5649 | @samp{0x1ae}, while in Modula-2 they appear as @samp{1AEH}. |
c906108c SS |
5650 | |
5651 | @cindex working language | |
5652 | Language-specific information is built into @value{GDBN} for some languages, | |
5653 | allowing you to express operations like the above in your program's | |
5654 | native language, and allowing @value{GDBN} to output values in a manner | |
5655 | consistent with the syntax of your program's native language. The | |
5656 | language you use to build expressions is called the @dfn{working | |
5657 | language}. | |
5658 | ||
5659 | @menu | |
5660 | * Setting:: Switching between source languages | |
5661 | * Show:: Displaying the language | |
c906108c | 5662 | * Checks:: Type and range checks |
c906108c SS |
5663 | * Support:: Supported languages |
5664 | @end menu | |
5665 | ||
6d2ebf8b | 5666 | @node Setting |
c906108c SS |
5667 | @section Switching between source languages |
5668 | ||
5669 | There are two ways to control the working language---either have @value{GDBN} | |
5670 | set it automatically, or select it manually yourself. You can use the | |
5671 | @code{set language} command for either purpose. On startup, @value{GDBN} | |
5672 | defaults to setting the language automatically. The working language is | |
5673 | used to determine how expressions you type are interpreted, how values | |
5674 | are printed, etc. | |
5675 | ||
5676 | In addition to the working language, every source file that | |
5677 | @value{GDBN} knows about has its own working language. For some object | |
5678 | file formats, the compiler might indicate which language a particular | |
5679 | source file is in. However, most of the time @value{GDBN} infers the | |
5680 | language from the name of the file. The language of a source file | |
5681 | controls whether C++ names are demangled---this way @code{backtrace} can | |
5682 | show each frame appropriately for its own language. There is no way to | |
d4f3574e SS |
5683 | set the language of a source file from within @value{GDBN}, but you can |
5684 | set the language associated with a filename extension. @xref{Show, , | |
5685 | Displaying the language}. | |
c906108c SS |
5686 | |
5687 | This is most commonly a problem when you use a program, such | |
5d161b24 | 5688 | as @code{cfront} or @code{f2c}, that generates C but is written in |
c906108c SS |
5689 | another language. In that case, make the |
5690 | program use @code{#line} directives in its C output; that way | |
5691 | @value{GDBN} will know the correct language of the source code of the original | |
5692 | program, and will display that source code, not the generated C code. | |
5693 | ||
5694 | @menu | |
5695 | * Filenames:: Filename extensions and languages. | |
5696 | * Manually:: Setting the working language manually | |
5697 | * Automatically:: Having @value{GDBN} infer the source language | |
5698 | @end menu | |
5699 | ||
6d2ebf8b | 5700 | @node Filenames |
c906108c SS |
5701 | @subsection List of filename extensions and languages |
5702 | ||
5703 | If a source file name ends in one of the following extensions, then | |
5704 | @value{GDBN} infers that its language is the one indicated. | |
5705 | ||
5706 | @table @file | |
5707 | ||
5708 | @item .c | |
5709 | C source file | |
5710 | ||
5711 | @item .C | |
5712 | @itemx .cc | |
5713 | @itemx .cp | |
5714 | @itemx .cpp | |
5715 | @itemx .cxx | |
5716 | @itemx .c++ | |
5717 | C++ source file | |
5718 | ||
5719 | @item .f | |
5720 | @itemx .F | |
5721 | Fortran source file | |
5722 | ||
c906108c SS |
5723 | @item .ch |
5724 | @itemx .c186 | |
5725 | @itemx .c286 | |
96a2c332 | 5726 | CHILL source file |
c906108c | 5727 | |
c906108c SS |
5728 | @item .mod |
5729 | Modula-2 source file | |
c906108c SS |
5730 | |
5731 | @item .s | |
5732 | @itemx .S | |
5733 | Assembler source file. This actually behaves almost like C, but | |
5734 | @value{GDBN} does not skip over function prologues when stepping. | |
5735 | @end table | |
5736 | ||
5737 | In addition, you may set the language associated with a filename | |
5738 | extension. @xref{Show, , Displaying the language}. | |
5739 | ||
6d2ebf8b | 5740 | @node Manually |
c906108c SS |
5741 | @subsection Setting the working language |
5742 | ||
5743 | If you allow @value{GDBN} to set the language automatically, | |
5744 | expressions are interpreted the same way in your debugging session and | |
5745 | your program. | |
5746 | ||
5747 | @kindex set language | |
5748 | If you wish, you may set the language manually. To do this, issue the | |
5749 | command @samp{set language @var{lang}}, where @var{lang} is the name of | |
5d161b24 | 5750 | a language, such as |
c906108c | 5751 | @code{c} or @code{modula-2}. |
c906108c SS |
5752 | For a list of the supported languages, type @samp{set language}. |
5753 | ||
c906108c SS |
5754 | Setting the language manually prevents @value{GDBN} from updating the working |
5755 | language automatically. This can lead to confusion if you try | |
5756 | to debug a program when the working language is not the same as the | |
5757 | source language, when an expression is acceptable to both | |
5758 | languages---but means different things. For instance, if the current | |
5759 | source file were written in C, and @value{GDBN} was parsing Modula-2, a | |
5760 | command such as: | |
5761 | ||
5762 | @example | |
5763 | print a = b + c | |
5764 | @end example | |
5765 | ||
5766 | @noindent | |
5767 | might not have the effect you intended. In C, this means to add | |
5768 | @code{b} and @code{c} and place the result in @code{a}. The result | |
5769 | printed would be the value of @code{a}. In Modula-2, this means to compare | |
5770 | @code{a} to the result of @code{b+c}, yielding a @code{BOOLEAN} value. | |
c906108c | 5771 | |
6d2ebf8b | 5772 | @node Automatically |
c906108c SS |
5773 | @subsection Having @value{GDBN} infer the source language |
5774 | ||
5775 | To have @value{GDBN} set the working language automatically, use | |
5776 | @samp{set language local} or @samp{set language auto}. @value{GDBN} | |
5777 | then infers the working language. That is, when your program stops in a | |
5778 | frame (usually by encountering a breakpoint), @value{GDBN} sets the | |
5779 | working language to the language recorded for the function in that | |
5780 | frame. If the language for a frame is unknown (that is, if the function | |
5781 | or block corresponding to the frame was defined in a source file that | |
5782 | does not have a recognized extension), the current working language is | |
5783 | not changed, and @value{GDBN} issues a warning. | |
5784 | ||
5785 | This may not seem necessary for most programs, which are written | |
5786 | entirely in one source language. However, program modules and libraries | |
5787 | written in one source language can be used by a main program written in | |
5788 | a different source language. Using @samp{set language auto} in this | |
5789 | case frees you from having to set the working language manually. | |
5790 | ||
6d2ebf8b | 5791 | @node Show |
c906108c | 5792 | @section Displaying the language |
c906108c SS |
5793 | |
5794 | The following commands help you find out which language is the | |
5795 | working language, and also what language source files were written in. | |
5796 | ||
5797 | @kindex show language | |
d4f3574e SS |
5798 | @kindex info frame@r{, show the source language} |
5799 | @kindex info source@r{, show the source language} | |
c906108c SS |
5800 | @table @code |
5801 | @item show language | |
5802 | Display the current working language. This is the | |
5803 | language you can use with commands such as @code{print} to | |
5804 | build and compute expressions that may involve variables in your program. | |
5805 | ||
5806 | @item info frame | |
5d161b24 | 5807 | Display the source language for this frame. This language becomes the |
c906108c | 5808 | working language if you use an identifier from this frame. |
5d161b24 | 5809 | @xref{Frame Info, ,Information about a frame}, to identify the other |
c906108c SS |
5810 | information listed here. |
5811 | ||
5812 | @item info source | |
5813 | Display the source language of this source file. | |
5d161b24 | 5814 | @xref{Symbols, ,Examining the Symbol Table}, to identify the other |
c906108c SS |
5815 | information listed here. |
5816 | @end table | |
5817 | ||
5818 | In unusual circumstances, you may have source files with extensions | |
5819 | not in the standard list. You can then set the extension associated | |
5820 | with a language explicitly: | |
5821 | ||
5822 | @kindex set extension-language | |
5823 | @kindex info extensions | |
5824 | @table @code | |
5825 | @item set extension-language @var{.ext} @var{language} | |
5826 | Set source files with extension @var{.ext} to be assumed to be in | |
5827 | the source language @var{language}. | |
5828 | ||
5829 | @item info extensions | |
5830 | List all the filename extensions and the associated languages. | |
5831 | @end table | |
5832 | ||
6d2ebf8b | 5833 | @node Checks |
c906108c SS |
5834 | @section Type and range checking |
5835 | ||
5836 | @quotation | |
5837 | @emph{Warning:} In this release, the @value{GDBN} commands for type and range | |
5838 | checking are included, but they do not yet have any effect. This | |
5839 | section documents the intended facilities. | |
5840 | @end quotation | |
5841 | @c FIXME remove warning when type/range code added | |
5842 | ||
5843 | Some languages are designed to guard you against making seemingly common | |
5844 | errors through a series of compile- and run-time checks. These include | |
5845 | checking the type of arguments to functions and operators, and making | |
5846 | sure mathematical overflows are caught at run time. Checks such as | |
5847 | these help to ensure a program's correctness once it has been compiled | |
5848 | by eliminating type mismatches, and providing active checks for range | |
5849 | errors when your program is running. | |
5850 | ||
5851 | @value{GDBN} can check for conditions like the above if you wish. | |
5852 | Although @value{GDBN} does not check the statements in your program, it | |
5853 | can check expressions entered directly into @value{GDBN} for evaluation via | |
5854 | the @code{print} command, for example. As with the working language, | |
5855 | @value{GDBN} can also decide whether or not to check automatically based on | |
5856 | your program's source language. @xref{Support, ,Supported languages}, | |
5857 | for the default settings of supported languages. | |
5858 | ||
5859 | @menu | |
5860 | * Type Checking:: An overview of type checking | |
5861 | * Range Checking:: An overview of range checking | |
5862 | @end menu | |
5863 | ||
5864 | @cindex type checking | |
5865 | @cindex checks, type | |
6d2ebf8b | 5866 | @node Type Checking |
c906108c SS |
5867 | @subsection An overview of type checking |
5868 | ||
5869 | Some languages, such as Modula-2, are strongly typed, meaning that the | |
5870 | arguments to operators and functions have to be of the correct type, | |
5871 | otherwise an error occurs. These checks prevent type mismatch | |
5872 | errors from ever causing any run-time problems. For example, | |
5873 | ||
5874 | @smallexample | |
5875 | 1 + 2 @result{} 3 | |
5876 | @exdent but | |
5877 | @error{} 1 + 2.3 | |
5878 | @end smallexample | |
5879 | ||
5880 | The second example fails because the @code{CARDINAL} 1 is not | |
5881 | type-compatible with the @code{REAL} 2.3. | |
5882 | ||
5d161b24 DB |
5883 | For the expressions you use in @value{GDBN} commands, you can tell the |
5884 | @value{GDBN} type checker to skip checking; | |
5885 | to treat any mismatches as errors and abandon the expression; | |
5886 | or to only issue warnings when type mismatches occur, | |
c906108c SS |
5887 | but evaluate the expression anyway. When you choose the last of |
5888 | these, @value{GDBN} evaluates expressions like the second example above, but | |
5889 | also issues a warning. | |
5890 | ||
5d161b24 DB |
5891 | Even if you turn type checking off, there may be other reasons |
5892 | related to type that prevent @value{GDBN} from evaluating an expression. | |
5893 | For instance, @value{GDBN} does not know how to add an @code{int} and | |
5894 | a @code{struct foo}. These particular type errors have nothing to do | |
5895 | with the language in use, and usually arise from expressions, such as | |
c906108c SS |
5896 | the one described above, which make little sense to evaluate anyway. |
5897 | ||
5898 | Each language defines to what degree it is strict about type. For | |
5899 | instance, both Modula-2 and C require the arguments to arithmetical | |
5900 | operators to be numbers. In C, enumerated types and pointers can be | |
5901 | represented as numbers, so that they are valid arguments to mathematical | |
5902 | operators. @xref{Support, ,Supported languages}, for further | |
5903 | details on specific languages. | |
5904 | ||
5905 | @value{GDBN} provides some additional commands for controlling the type checker: | |
5906 | ||
d4f3574e | 5907 | @kindex set check@r{, type} |
c906108c SS |
5908 | @kindex set check type |
5909 | @kindex show check type | |
5910 | @table @code | |
5911 | @item set check type auto | |
5912 | Set type checking on or off based on the current working language. | |
5913 | @xref{Support, ,Supported languages}, for the default settings for | |
5914 | each language. | |
5915 | ||
5916 | @item set check type on | |
5917 | @itemx set check type off | |
5918 | Set type checking on or off, overriding the default setting for the | |
5919 | current working language. Issue a warning if the setting does not | |
5920 | match the language default. If any type mismatches occur in | |
d4f3574e | 5921 | evaluating an expression while type checking is on, @value{GDBN} prints a |
c906108c SS |
5922 | message and aborts evaluation of the expression. |
5923 | ||
5924 | @item set check type warn | |
5925 | Cause the type checker to issue warnings, but to always attempt to | |
5926 | evaluate the expression. Evaluating the expression may still | |
5927 | be impossible for other reasons. For example, @value{GDBN} cannot add | |
5928 | numbers and structures. | |
5929 | ||
5930 | @item show type | |
5d161b24 | 5931 | Show the current setting of the type checker, and whether or not @value{GDBN} |
c906108c SS |
5932 | is setting it automatically. |
5933 | @end table | |
5934 | ||
5935 | @cindex range checking | |
5936 | @cindex checks, range | |
6d2ebf8b | 5937 | @node Range Checking |
c906108c SS |
5938 | @subsection An overview of range checking |
5939 | ||
5940 | In some languages (such as Modula-2), it is an error to exceed the | |
5941 | bounds of a type; this is enforced with run-time checks. Such range | |
5942 | checking is meant to ensure program correctness by making sure | |
5943 | computations do not overflow, or indices on an array element access do | |
5944 | not exceed the bounds of the array. | |
5945 | ||
5946 | For expressions you use in @value{GDBN} commands, you can tell | |
5947 | @value{GDBN} to treat range errors in one of three ways: ignore them, | |
5948 | always treat them as errors and abandon the expression, or issue | |
5949 | warnings but evaluate the expression anyway. | |
5950 | ||
5951 | A range error can result from numerical overflow, from exceeding an | |
5952 | array index bound, or when you type a constant that is not a member | |
5953 | of any type. Some languages, however, do not treat overflows as an | |
5954 | error. In many implementations of C, mathematical overflow causes the | |
5955 | result to ``wrap around'' to lower values---for example, if @var{m} is | |
5956 | the largest integer value, and @var{s} is the smallest, then | |
5957 | ||
5958 | @example | |
5959 | @var{m} + 1 @result{} @var{s} | |
5960 | @end example | |
5961 | ||
5962 | This, too, is specific to individual languages, and in some cases | |
5963 | specific to individual compilers or machines. @xref{Support, , | |
5964 | Supported languages}, for further details on specific languages. | |
5965 | ||
5966 | @value{GDBN} provides some additional commands for controlling the range checker: | |
5967 | ||
d4f3574e | 5968 | @kindex set check@r{, range} |
c906108c SS |
5969 | @kindex set check range |
5970 | @kindex show check range | |
5971 | @table @code | |
5972 | @item set check range auto | |
5973 | Set range checking on or off based on the current working language. | |
5974 | @xref{Support, ,Supported languages}, for the default settings for | |
5975 | each language. | |
5976 | ||
5977 | @item set check range on | |
5978 | @itemx set check range off | |
5979 | Set range checking on or off, overriding the default setting for the | |
5980 | current working language. A warning is issued if the setting does not | |
c3f6f71d JM |
5981 | match the language default. If a range error occurs and range checking is on, |
5982 | then a message is printed and evaluation of the expression is aborted. | |
c906108c SS |
5983 | |
5984 | @item set check range warn | |
5985 | Output messages when the @value{GDBN} range checker detects a range error, | |
5986 | but attempt to evaluate the expression anyway. Evaluating the | |
5987 | expression may still be impossible for other reasons, such as accessing | |
5988 | memory that the process does not own (a typical example from many Unix | |
5989 | systems). | |
5990 | ||
5991 | @item show range | |
5992 | Show the current setting of the range checker, and whether or not it is | |
5993 | being set automatically by @value{GDBN}. | |
5994 | @end table | |
c906108c | 5995 | |
6d2ebf8b | 5996 | @node Support |
c906108c | 5997 | @section Supported languages |
c906108c | 5998 | |
cce74817 JM |
5999 | @value{GDBN} supports C, C++, Fortran, Java, Chill, assembly, and Modula-2. |
6000 | @c This is false ... | |
c906108c SS |
6001 | Some @value{GDBN} features may be used in expressions regardless of the |
6002 | language you use: the @value{GDBN} @code{@@} and @code{::} operators, | |
6003 | and the @samp{@{type@}addr} construct (@pxref{Expressions, | |
6004 | ,Expressions}) can be used with the constructs of any supported | |
6005 | language. | |
6006 | ||
6007 | The following sections detail to what degree each source language is | |
6008 | supported by @value{GDBN}. These sections are not meant to be language | |
6009 | tutorials or references, but serve only as a reference guide to what the | |
6010 | @value{GDBN} expression parser accepts, and what input and output | |
6011 | formats should look like for different languages. There are many good | |
6012 | books written on each of these languages; please look to these for a | |
6013 | language reference or tutorial. | |
6014 | ||
c906108c | 6015 | @menu |
7a292a7a | 6016 | * C:: C and C++ |
cce74817 | 6017 | * Modula-2:: Modula-2 |
104c1213 | 6018 | * Chill:: Chill |
c906108c SS |
6019 | @end menu |
6020 | ||
6d2ebf8b | 6021 | @node C |
c906108c | 6022 | @subsection C and C++ |
7a292a7a | 6023 | |
c906108c SS |
6024 | @cindex C and C++ |
6025 | @cindex expressions in C or C++ | |
c906108c SS |
6026 | |
6027 | Since C and C++ are so closely related, many features of @value{GDBN} apply | |
6028 | to both languages. Whenever this is the case, we discuss those languages | |
6029 | together. | |
6030 | ||
41afff9a EZ |
6031 | @cindex C@t{++} |
6032 | @cindex @code{g++}, @sc{gnu} C@t{++} compiler | |
c906108c SS |
6033 | @cindex @sc{gnu} C++ |
6034 | The C++ debugging facilities are jointly implemented by the C++ | |
6035 | compiler and @value{GDBN}. Therefore, to debug your C++ code | |
6036 | effectively, you must compile your C++ programs with a supported | |
6037 | C++ compiler, such as @sc{gnu} @code{g++}, or the HP ANSI C++ | |
6038 | compiler (@code{aCC}). | |
6039 | ||
6040 | For best results when using @sc{gnu} C++, use the stabs debugging | |
6041 | format. You can select that format explicitly with the @code{g++} | |
6042 | command-line options @samp{-gstabs} or @samp{-gstabs+}. See | |
6043 | @ref{Debugging Options,,Options for Debugging Your Program or @sc{gnu} | |
6044 | CC, gcc.info, Using @sc{gnu} CC}, for more information. | |
c906108c | 6045 | |
c906108c SS |
6046 | @menu |
6047 | * C Operators:: C and C++ operators | |
6048 | * C Constants:: C and C++ constants | |
7a292a7a | 6049 | * C plus plus expressions:: C++ expressions |
c906108c | 6050 | * C Defaults:: Default settings for C and C++ |
c906108c | 6051 | * C Checks:: C and C++ type and range checks |
c906108c SS |
6052 | * Debugging C:: @value{GDBN} and C |
6053 | * Debugging C plus plus:: @value{GDBN} features for C++ | |
6054 | @end menu | |
c906108c | 6055 | |
6d2ebf8b | 6056 | @node C Operators |
c906108c | 6057 | @subsubsection C and C++ operators |
7a292a7a SS |
6058 | |
6059 | @cindex C and C++ operators | |
c906108c SS |
6060 | |
6061 | Operators must be defined on values of specific types. For instance, | |
6062 | @code{+} is defined on numbers, but not on structures. Operators are | |
5d161b24 | 6063 | often defined on groups of types. |
c906108c | 6064 | |
c906108c | 6065 | For the purposes of C and C++, the following definitions hold: |
c906108c SS |
6066 | |
6067 | @itemize @bullet | |
53a5351d | 6068 | |
c906108c | 6069 | @item |
c906108c SS |
6070 | @emph{Integral types} include @code{int} with any of its storage-class |
6071 | specifiers; @code{char}; @code{enum}; and, for C++, @code{bool}. | |
c906108c SS |
6072 | |
6073 | @item | |
d4f3574e SS |
6074 | @emph{Floating-point types} include @code{float}, @code{double}, and |
6075 | @code{long double} (if supported by the target platform). | |
c906108c SS |
6076 | |
6077 | @item | |
53a5351d | 6078 | @emph{Pointer types} include all types defined as @code{(@var{type} *)}. |
c906108c SS |
6079 | |
6080 | @item | |
6081 | @emph{Scalar types} include all of the above. | |
53a5351d | 6082 | |
c906108c SS |
6083 | @end itemize |
6084 | ||
6085 | @noindent | |
6086 | The following operators are supported. They are listed here | |
6087 | in order of increasing precedence: | |
6088 | ||
6089 | @table @code | |
6090 | @item , | |
6091 | The comma or sequencing operator. Expressions in a comma-separated list | |
6092 | are evaluated from left to right, with the result of the entire | |
6093 | expression being the last expression evaluated. | |
6094 | ||
6095 | @item = | |
6096 | Assignment. The value of an assignment expression is the value | |
6097 | assigned. Defined on scalar types. | |
6098 | ||
6099 | @item @var{op}= | |
6100 | Used in an expression of the form @w{@code{@var{a} @var{op}= @var{b}}}, | |
6101 | and translated to @w{@code{@var{a} = @var{a op b}}}. | |
d4f3574e | 6102 | @w{@code{@var{op}=}} and @code{=} have the same precedence. |
c906108c SS |
6103 | @var{op} is any one of the operators @code{|}, @code{^}, @code{&}, |
6104 | @code{<<}, @code{>>}, @code{+}, @code{-}, @code{*}, @code{/}, @code{%}. | |
6105 | ||
6106 | @item ?: | |
6107 | The ternary operator. @code{@var{a} ? @var{b} : @var{c}} can be thought | |
6108 | of as: if @var{a} then @var{b} else @var{c}. @var{a} should be of an | |
6109 | integral type. | |
6110 | ||
6111 | @item || | |
6112 | Logical @sc{or}. Defined on integral types. | |
6113 | ||
6114 | @item && | |
6115 | Logical @sc{and}. Defined on integral types. | |
6116 | ||
6117 | @item | | |
6118 | Bitwise @sc{or}. Defined on integral types. | |
6119 | ||
6120 | @item ^ | |
6121 | Bitwise exclusive-@sc{or}. Defined on integral types. | |
6122 | ||
6123 | @item & | |
6124 | Bitwise @sc{and}. Defined on integral types. | |
6125 | ||
6126 | @item ==@r{, }!= | |
6127 | Equality and inequality. Defined on scalar types. The value of these | |
6128 | expressions is 0 for false and non-zero for true. | |
6129 | ||
6130 | @item <@r{, }>@r{, }<=@r{, }>= | |
6131 | Less than, greater than, less than or equal, greater than or equal. | |
6132 | Defined on scalar types. The value of these expressions is 0 for false | |
6133 | and non-zero for true. | |
6134 | ||
6135 | @item <<@r{, }>> | |
6136 | left shift, and right shift. Defined on integral types. | |
6137 | ||
6138 | @item @@ | |
6139 | The @value{GDBN} ``artificial array'' operator (@pxref{Expressions, ,Expressions}). | |
6140 | ||
6141 | @item +@r{, }- | |
6142 | Addition and subtraction. Defined on integral types, floating-point types and | |
6143 | pointer types. | |
6144 | ||
6145 | @item *@r{, }/@r{, }% | |
6146 | Multiplication, division, and modulus. Multiplication and division are | |
6147 | defined on integral and floating-point types. Modulus is defined on | |
6148 | integral types. | |
6149 | ||
6150 | @item ++@r{, }-- | |
6151 | Increment and decrement. When appearing before a variable, the | |
6152 | operation is performed before the variable is used in an expression; | |
6153 | when appearing after it, the variable's value is used before the | |
6154 | operation takes place. | |
6155 | ||
6156 | @item * | |
6157 | Pointer dereferencing. Defined on pointer types. Same precedence as | |
6158 | @code{++}. | |
6159 | ||
6160 | @item & | |
6161 | Address operator. Defined on variables. Same precedence as @code{++}. | |
6162 | ||
c906108c SS |
6163 | For debugging C++, @value{GDBN} implements a use of @samp{&} beyond what is |
6164 | allowed in the C++ language itself: you can use @samp{&(&@var{ref})} | |
6165 | (or, if you prefer, simply @samp{&&@var{ref}}) to examine the address | |
6166 | where a C++ reference variable (declared with @samp{&@var{ref}}) is | |
6167 | stored. | |
c906108c SS |
6168 | |
6169 | @item - | |
6170 | Negative. Defined on integral and floating-point types. Same | |
6171 | precedence as @code{++}. | |
6172 | ||
6173 | @item ! | |
6174 | Logical negation. Defined on integral types. Same precedence as | |
6175 | @code{++}. | |
6176 | ||
6177 | @item ~ | |
6178 | Bitwise complement operator. Defined on integral types. Same precedence as | |
6179 | @code{++}. | |
6180 | ||
6181 | ||
6182 | @item .@r{, }-> | |
6183 | Structure member, and pointer-to-structure member. For convenience, | |
6184 | @value{GDBN} regards the two as equivalent, choosing whether to dereference a | |
6185 | pointer based on the stored type information. | |
6186 | Defined on @code{struct} and @code{union} data. | |
6187 | ||
c906108c SS |
6188 | @item .*@r{, }->* |
6189 | Dereferences of pointers to members. | |
c906108c SS |
6190 | |
6191 | @item [] | |
6192 | Array indexing. @code{@var{a}[@var{i}]} is defined as | |
6193 | @code{*(@var{a}+@var{i})}. Same precedence as @code{->}. | |
6194 | ||
6195 | @item () | |
6196 | Function parameter list. Same precedence as @code{->}. | |
6197 | ||
c906108c | 6198 | @item :: |
7a292a7a SS |
6199 | C++ scope resolution operator. Defined on @code{struct}, @code{union}, |
6200 | and @code{class} types. | |
c906108c SS |
6201 | |
6202 | @item :: | |
7a292a7a SS |
6203 | Doubled colons also represent the @value{GDBN} scope operator |
6204 | (@pxref{Expressions, ,Expressions}). Same precedence as @code{::}, | |
6205 | above. | |
c906108c SS |
6206 | @end table |
6207 | ||
c906108c SS |
6208 | If an operator is redefined in the user code, @value{GDBN} usually |
6209 | attempts to invoke the redefined version instead of using the operator's | |
6210 | predefined meaning. | |
c906108c | 6211 | |
c906108c | 6212 | @menu |
5d161b24 | 6213 | * C Constants:: |
c906108c SS |
6214 | @end menu |
6215 | ||
6d2ebf8b | 6216 | @node C Constants |
c906108c | 6217 | @subsubsection C and C++ constants |
c906108c SS |
6218 | |
6219 | @cindex C and C++ constants | |
c906108c | 6220 | |
7a292a7a | 6221 | @value{GDBN} allows you to express the constants of C and C++ in the |
c906108c | 6222 | following ways: |
c906108c SS |
6223 | |
6224 | @itemize @bullet | |
6225 | @item | |
6226 | Integer constants are a sequence of digits. Octal constants are | |
6227 | specified by a leading @samp{0} (i.e. zero), and hexadecimal constants by | |
6228 | a leading @samp{0x} or @samp{0X}. Constants may also end with a letter | |
6229 | @samp{l}, specifying that the constant should be treated as a | |
6230 | @code{long} value. | |
6231 | ||
6232 | @item | |
6233 | Floating point constants are a sequence of digits, followed by a decimal | |
6234 | point, followed by a sequence of digits, and optionally followed by an | |
6235 | exponent. An exponent is of the form: | |
6236 | @samp{@w{e@r{[[}+@r{]|}-@r{]}@var{nnn}}}, where @var{nnn} is another | |
6237 | sequence of digits. The @samp{+} is optional for positive exponents. | |
d4f3574e SS |
6238 | A floating-point constant may also end with a letter @samp{f} or |
6239 | @samp{F}, specifying that the constant should be treated as being of | |
6240 | the @code{float} (as opposed to the default @code{double}) type; or with | |
6241 | a letter @samp{l} or @samp{L}, which specifies a @code{long double} | |
6242 | constant. | |
c906108c SS |
6243 | |
6244 | @item | |
6245 | Enumerated constants consist of enumerated identifiers, or their | |
6246 | integral equivalents. | |
6247 | ||
6248 | @item | |
6249 | Character constants are a single character surrounded by single quotes | |
6250 | (@code{'}), or a number---the ordinal value of the corresponding character | |
d4f3574e | 6251 | (usually its @sc{ascii} value). Within quotes, the single character may |
c906108c SS |
6252 | be represented by a letter or by @dfn{escape sequences}, which are of |
6253 | the form @samp{\@var{nnn}}, where @var{nnn} is the octal representation | |
6254 | of the character's ordinal value; or of the form @samp{\@var{x}}, where | |
6255 | @samp{@var{x}} is a predefined special character---for example, | |
6256 | @samp{\n} for newline. | |
6257 | ||
6258 | @item | |
96a2c332 SS |
6259 | String constants are a sequence of character constants surrounded by |
6260 | double quotes (@code{"}). Any valid character constant (as described | |
6261 | above) may appear. Double quotes within the string must be preceded by | |
6262 | a backslash, so for instance @samp{"a\"b'c"} is a string of five | |
6263 | characters. | |
c906108c SS |
6264 | |
6265 | @item | |
6266 | Pointer constants are an integral value. You can also write pointers | |
6267 | to constants using the C operator @samp{&}. | |
6268 | ||
6269 | @item | |
6270 | Array constants are comma-separated lists surrounded by braces @samp{@{} | |
6271 | and @samp{@}}; for example, @samp{@{1,2,3@}} is a three-element array of | |
6272 | integers, @samp{@{@{1,2@}, @{3,4@}, @{5,6@}@}} is a three-by-two array, | |
6273 | and @samp{@{&"hi", &"there", &"fred"@}} is a three-element array of pointers. | |
6274 | @end itemize | |
6275 | ||
c906108c | 6276 | @menu |
5d161b24 DB |
6277 | * C plus plus expressions:: |
6278 | * C Defaults:: | |
6279 | * C Checks:: | |
c906108c | 6280 | |
5d161b24 | 6281 | * Debugging C:: |
c906108c SS |
6282 | @end menu |
6283 | ||
6d2ebf8b | 6284 | @node C plus plus expressions |
c906108c | 6285 | @subsubsection C++ expressions |
c906108c SS |
6286 | |
6287 | @cindex expressions in C++ | |
6288 | @value{GDBN} expression handling can interpret most C++ expressions. | |
6289 | ||
c906108c SS |
6290 | @cindex C++ support, not in @sc{coff} |
6291 | @cindex @sc{coff} versus C++ | |
6292 | @cindex C++ and object formats | |
6293 | @cindex object formats and C++ | |
6294 | @cindex a.out and C++ | |
6295 | @cindex @sc{ecoff} and C++ | |
6296 | @cindex @sc{xcoff} and C++ | |
6297 | @cindex @sc{elf}/stabs and C++ | |
6298 | @cindex @sc{elf}/@sc{dwarf} and C++ | |
6299 | @c FIXME!! GDB may eventually be able to debug C++ using DWARF; check | |
6300 | @c periodically whether this has happened... | |
6301 | @quotation | |
6302 | @emph{Warning:} @value{GDBN} can only debug C++ code if you use the | |
6303 | proper compiler. Typically, C++ debugging depends on the use of | |
6304 | additional debugging information in the symbol table, and thus requires | |
6305 | special support. In particular, if your compiler generates a.out, MIPS | |
6306 | @sc{ecoff}, RS/6000 @sc{xcoff}, or @sc{elf} with stabs extensions to the | |
6307 | symbol table, these facilities are all available. (With @sc{gnu} CC, | |
6308 | you can use the @samp{-gstabs} option to request stabs debugging | |
6309 | extensions explicitly.) Where the object code format is standard | |
6310 | @sc{coff} or @sc{dwarf} in @sc{elf}, on the other hand, most of the C++ | |
6311 | support in @value{GDBN} does @emph{not} work. | |
6312 | @end quotation | |
c906108c SS |
6313 | |
6314 | @enumerate | |
6315 | ||
6316 | @cindex member functions | |
6317 | @item | |
6318 | Member function calls are allowed; you can use expressions like | |
6319 | ||
6320 | @example | |
6321 | count = aml->GetOriginal(x, y) | |
6322 | @end example | |
6323 | ||
41afff9a | 6324 | @vindex this@r{, inside C@t{++} member functions} |
c906108c SS |
6325 | @cindex namespace in C++ |
6326 | @item | |
6327 | While a member function is active (in the selected stack frame), your | |
6328 | expressions have the same namespace available as the member function; | |
6329 | that is, @value{GDBN} allows implicit references to the class instance | |
6330 | pointer @code{this} following the same rules as C++. | |
6331 | ||
c906108c | 6332 | @cindex call overloaded functions |
d4f3574e | 6333 | @cindex overloaded functions, calling |
c906108c SS |
6334 | @cindex type conversions in C++ |
6335 | @item | |
6336 | You can call overloaded functions; @value{GDBN} resolves the function | |
d4f3574e | 6337 | call to the right definition, with some restrictions. @value{GDBN} does not |
c906108c SS |
6338 | perform overload resolution involving user-defined type conversions, |
6339 | calls to constructors, or instantiations of templates that do not exist | |
6340 | in the program. It also cannot handle ellipsis argument lists or | |
6341 | default arguments. | |
6342 | ||
6343 | It does perform integral conversions and promotions, floating-point | |
6344 | promotions, arithmetic conversions, pointer conversions, conversions of | |
6345 | class objects to base classes, and standard conversions such as those of | |
6346 | functions or arrays to pointers; it requires an exact match on the | |
6347 | number of function arguments. | |
6348 | ||
6349 | Overload resolution is always performed, unless you have specified | |
6350 | @code{set overload-resolution off}. @xref{Debugging C plus plus, | |
6351 | ,@value{GDBN} features for C++}. | |
6352 | ||
d4f3574e | 6353 | You must specify @code{set overload-resolution off} in order to use an |
c906108c SS |
6354 | explicit function signature to call an overloaded function, as in |
6355 | @smallexample | |
6356 | p 'foo(char,int)'('x', 13) | |
6357 | @end smallexample | |
d4f3574e | 6358 | |
c906108c | 6359 | The @value{GDBN} command-completion facility can simplify this; |
d4f3574e | 6360 | see @ref{Completion, ,Command completion}. |
c906108c | 6361 | |
c906108c SS |
6362 | @cindex reference declarations |
6363 | @item | |
5d161b24 | 6364 | @value{GDBN} understands variables declared as C++ references; you can use |
c906108c SS |
6365 | them in expressions just as you do in C++ source---they are automatically |
6366 | dereferenced. | |
6367 | ||
6368 | In the parameter list shown when @value{GDBN} displays a frame, the values of | |
6369 | reference variables are not displayed (unlike other variables); this | |
6370 | avoids clutter, since references are often used for large structures. | |
6371 | The @emph{address} of a reference variable is always shown, unless | |
6372 | you have specified @samp{set print address off}. | |
6373 | ||
6374 | @item | |
6375 | @value{GDBN} supports the C++ name resolution operator @code{::}---your | |
6376 | expressions can use it just as expressions in your program do. Since | |
6377 | one scope may be defined in another, you can use @code{::} repeatedly if | |
6378 | necessary, for example in an expression like | |
6379 | @samp{@var{scope1}::@var{scope2}::@var{name}}. @value{GDBN} also allows | |
6380 | resolving name scope by reference to source files, in both C and C++ | |
6381 | debugging (@pxref{Variables, ,Program variables}). | |
6382 | @end enumerate | |
6383 | ||
53a5351d JM |
6384 | In addition, when used with HP's C++ compiler, @value{GDBN} supports |
6385 | calling virtual functions correctly, printing out virtual bases of | |
6386 | objects, calling functions in a base subobject, casting objects, and | |
6387 | invoking user-defined operators. | |
c906108c | 6388 | |
6d2ebf8b | 6389 | @node C Defaults |
c906108c | 6390 | @subsubsection C and C++ defaults |
7a292a7a | 6391 | |
c906108c SS |
6392 | @cindex C and C++ defaults |
6393 | ||
c906108c SS |
6394 | If you allow @value{GDBN} to set type and range checking automatically, they |
6395 | both default to @code{off} whenever the working language changes to | |
6396 | C or C++. This happens regardless of whether you or @value{GDBN} | |
6397 | selects the working language. | |
c906108c SS |
6398 | |
6399 | If you allow @value{GDBN} to set the language automatically, it | |
6400 | recognizes source files whose names end with @file{.c}, @file{.C}, or | |
6401 | @file{.cc}, etc, and when @value{GDBN} enters code compiled from one of | |
6402 | these files, it sets the working language to C or C++. | |
6403 | @xref{Automatically, ,Having @value{GDBN} infer the source language}, | |
6404 | for further details. | |
6405 | ||
c906108c SS |
6406 | @c Type checking is (a) primarily motivated by Modula-2, and (b) |
6407 | @c unimplemented. If (b) changes, it might make sense to let this node | |
6408 | @c appear even if Mod-2 does not, but meanwhile ignore it. roland 16jul93. | |
7a292a7a | 6409 | |
6d2ebf8b | 6410 | @node C Checks |
c906108c | 6411 | @subsubsection C and C++ type and range checks |
7a292a7a | 6412 | |
c906108c SS |
6413 | @cindex C and C++ checks |
6414 | ||
6415 | By default, when @value{GDBN} parses C or C++ expressions, type checking | |
6416 | is not used. However, if you turn type checking on, @value{GDBN} | |
6417 | considers two variables type equivalent if: | |
6418 | ||
6419 | @itemize @bullet | |
6420 | @item | |
6421 | The two variables are structured and have the same structure, union, or | |
6422 | enumerated tag. | |
6423 | ||
6424 | @item | |
6425 | The two variables have the same type name, or types that have been | |
6426 | declared equivalent through @code{typedef}. | |
6427 | ||
6428 | @ignore | |
6429 | @c leaving this out because neither J Gilmore nor R Pesch understand it. | |
6430 | @c FIXME--beers? | |
6431 | @item | |
6432 | The two @code{struct}, @code{union}, or @code{enum} variables are | |
6433 | declared in the same declaration. (Note: this may not be true for all C | |
6434 | compilers.) | |
6435 | @end ignore | |
6436 | @end itemize | |
6437 | ||
6438 | Range checking, if turned on, is done on mathematical operations. Array | |
6439 | indices are not checked, since they are often used to index a pointer | |
6440 | that is not itself an array. | |
c906108c | 6441 | |
6d2ebf8b | 6442 | @node Debugging C |
c906108c | 6443 | @subsubsection @value{GDBN} and C |
c906108c SS |
6444 | |
6445 | The @code{set print union} and @code{show print union} commands apply to | |
6446 | the @code{union} type. When set to @samp{on}, any @code{union} that is | |
7a292a7a SS |
6447 | inside a @code{struct} or @code{class} is also printed. Otherwise, it |
6448 | appears as @samp{@{...@}}. | |
c906108c SS |
6449 | |
6450 | The @code{@@} operator aids in the debugging of dynamic arrays, formed | |
6451 | with pointers and a memory allocation function. @xref{Expressions, | |
6452 | ,Expressions}. | |
6453 | ||
c906108c | 6454 | @menu |
5d161b24 | 6455 | * Debugging C plus plus:: |
c906108c SS |
6456 | @end menu |
6457 | ||
6d2ebf8b | 6458 | @node Debugging C plus plus |
c906108c | 6459 | @subsubsection @value{GDBN} features for C++ |
c906108c SS |
6460 | |
6461 | @cindex commands for C++ | |
7a292a7a | 6462 | |
c906108c SS |
6463 | Some @value{GDBN} commands are particularly useful with C++, and some are |
6464 | designed specifically for use with C++. Here is a summary: | |
6465 | ||
6466 | @table @code | |
6467 | @cindex break in overloaded functions | |
6468 | @item @r{breakpoint menus} | |
6469 | When you want a breakpoint in a function whose name is overloaded, | |
6470 | @value{GDBN} breakpoint menus help you specify which function definition | |
6471 | you want. @xref{Breakpoint Menus,,Breakpoint menus}. | |
6472 | ||
6473 | @cindex overloading in C++ | |
6474 | @item rbreak @var{regex} | |
6475 | Setting breakpoints using regular expressions is helpful for setting | |
6476 | breakpoints on overloaded functions that are not members of any special | |
6477 | classes. | |
6478 | @xref{Set Breaks, ,Setting breakpoints}. | |
6479 | ||
6480 | @cindex C++ exception handling | |
6481 | @item catch throw | |
6482 | @itemx catch catch | |
6483 | Debug C++ exception handling using these commands. @xref{Set | |
6484 | Catchpoints, , Setting catchpoints}. | |
6485 | ||
6486 | @cindex inheritance | |
6487 | @item ptype @var{typename} | |
6488 | Print inheritance relationships as well as other information for type | |
6489 | @var{typename}. | |
6490 | @xref{Symbols, ,Examining the Symbol Table}. | |
6491 | ||
6492 | @cindex C++ symbol display | |
6493 | @item set print demangle | |
6494 | @itemx show print demangle | |
6495 | @itemx set print asm-demangle | |
6496 | @itemx show print asm-demangle | |
6497 | Control whether C++ symbols display in their source form, both when | |
6498 | displaying code as C++ source and when displaying disassemblies. | |
6499 | @xref{Print Settings, ,Print settings}. | |
6500 | ||
6501 | @item set print object | |
6502 | @itemx show print object | |
6503 | Choose whether to print derived (actual) or declared types of objects. | |
6504 | @xref{Print Settings, ,Print settings}. | |
6505 | ||
6506 | @item set print vtbl | |
6507 | @itemx show print vtbl | |
6508 | Control the format for printing virtual function tables. | |
6509 | @xref{Print Settings, ,Print settings}. | |
c906108c SS |
6510 | (The @code{vtbl} commands do not work on programs compiled with the HP |
6511 | ANSI C++ compiler (@code{aCC}).) | |
6512 | ||
6513 | @kindex set overload-resolution | |
d4f3574e | 6514 | @cindex overloaded functions, overload resolution |
c906108c SS |
6515 | @item set overload-resolution on |
6516 | Enable overload resolution for C++ expression evaluation. The default | |
6517 | is on. For overloaded functions, @value{GDBN} evaluates the arguments | |
6518 | and searches for a function whose signature matches the argument types, | |
d4f3574e SS |
6519 | using the standard C++ conversion rules (see @ref{C plus plus expressions, ,C++ |
6520 | expressions}, for details). If it cannot find a match, it emits a | |
c906108c SS |
6521 | message. |
6522 | ||
6523 | @item set overload-resolution off | |
6524 | Disable overload resolution for C++ expression evaluation. For | |
6525 | overloaded functions that are not class member functions, @value{GDBN} | |
6526 | chooses the first function of the specified name that it finds in the | |
6527 | symbol table, whether or not its arguments are of the correct type. For | |
6528 | overloaded functions that are class member functions, @value{GDBN} | |
6529 | searches for a function whose signature @emph{exactly} matches the | |
6530 | argument types. | |
c906108c SS |
6531 | |
6532 | @item @r{Overloaded symbol names} | |
6533 | You can specify a particular definition of an overloaded symbol, using | |
6534 | the same notation that is used to declare such symbols in C++: type | |
6535 | @code{@var{symbol}(@var{types})} rather than just @var{symbol}. You can | |
6536 | also use the @value{GDBN} command-line word completion facilities to list the | |
6537 | available choices, or to finish the type list for you. | |
6538 | @xref{Completion,, Command completion}, for details on how to do this. | |
6539 | @end table | |
c906108c | 6540 | |
6d2ebf8b | 6541 | @node Modula-2 |
c906108c | 6542 | @subsection Modula-2 |
7a292a7a | 6543 | |
d4f3574e | 6544 | @cindex Modula-2, @value{GDBN} support |
c906108c SS |
6545 | |
6546 | The extensions made to @value{GDBN} to support Modula-2 only support | |
6547 | output from the @sc{gnu} Modula-2 compiler (which is currently being | |
6548 | developed). Other Modula-2 compilers are not currently supported, and | |
6549 | attempting to debug executables produced by them is most likely | |
6550 | to give an error as @value{GDBN} reads in the executable's symbol | |
6551 | table. | |
6552 | ||
6553 | @cindex expressions in Modula-2 | |
6554 | @menu | |
6555 | * M2 Operators:: Built-in operators | |
6556 | * Built-In Func/Proc:: Built-in functions and procedures | |
6557 | * M2 Constants:: Modula-2 constants | |
6558 | * M2 Defaults:: Default settings for Modula-2 | |
6559 | * Deviations:: Deviations from standard Modula-2 | |
6560 | * M2 Checks:: Modula-2 type and range checks | |
6561 | * M2 Scope:: The scope operators @code{::} and @code{.} | |
6562 | * GDB/M2:: @value{GDBN} and Modula-2 | |
6563 | @end menu | |
6564 | ||
6d2ebf8b | 6565 | @node M2 Operators |
c906108c SS |
6566 | @subsubsection Operators |
6567 | @cindex Modula-2 operators | |
6568 | ||
6569 | Operators must be defined on values of specific types. For instance, | |
6570 | @code{+} is defined on numbers, but not on structures. Operators are | |
6571 | often defined on groups of types. For the purposes of Modula-2, the | |
6572 | following definitions hold: | |
6573 | ||
6574 | @itemize @bullet | |
6575 | ||
6576 | @item | |
6577 | @emph{Integral types} consist of @code{INTEGER}, @code{CARDINAL}, and | |
6578 | their subranges. | |
6579 | ||
6580 | @item | |
6581 | @emph{Character types} consist of @code{CHAR} and its subranges. | |
6582 | ||
6583 | @item | |
6584 | @emph{Floating-point types} consist of @code{REAL}. | |
6585 | ||
6586 | @item | |
6587 | @emph{Pointer types} consist of anything declared as @code{POINTER TO | |
6588 | @var{type}}. | |
6589 | ||
6590 | @item | |
6591 | @emph{Scalar types} consist of all of the above. | |
6592 | ||
6593 | @item | |
6594 | @emph{Set types} consist of @code{SET} and @code{BITSET} types. | |
6595 | ||
6596 | @item | |
6597 | @emph{Boolean types} consist of @code{BOOLEAN}. | |
6598 | @end itemize | |
6599 | ||
6600 | @noindent | |
6601 | The following operators are supported, and appear in order of | |
6602 | increasing precedence: | |
6603 | ||
6604 | @table @code | |
6605 | @item , | |
6606 | Function argument or array index separator. | |
6607 | ||
6608 | @item := | |
6609 | Assignment. The value of @var{var} @code{:=} @var{value} is | |
6610 | @var{value}. | |
6611 | ||
6612 | @item <@r{, }> | |
6613 | Less than, greater than on integral, floating-point, or enumerated | |
6614 | types. | |
6615 | ||
6616 | @item <=@r{, }>= | |
96a2c332 | 6617 | Less than or equal to, greater than or equal to |
c906108c SS |
6618 | on integral, floating-point and enumerated types, or set inclusion on |
6619 | set types. Same precedence as @code{<}. | |
6620 | ||
6621 | @item =@r{, }<>@r{, }# | |
6622 | Equality and two ways of expressing inequality, valid on scalar types. | |
6623 | Same precedence as @code{<}. In @value{GDBN} scripts, only @code{<>} is | |
6624 | available for inequality, since @code{#} conflicts with the script | |
6625 | comment character. | |
6626 | ||
6627 | @item IN | |
6628 | Set membership. Defined on set types and the types of their members. | |
6629 | Same precedence as @code{<}. | |
6630 | ||
6631 | @item OR | |
6632 | Boolean disjunction. Defined on boolean types. | |
6633 | ||
6634 | @item AND@r{, }& | |
d4f3574e | 6635 | Boolean conjunction. Defined on boolean types. |
c906108c SS |
6636 | |
6637 | @item @@ | |
6638 | The @value{GDBN} ``artificial array'' operator (@pxref{Expressions, ,Expressions}). | |
6639 | ||
6640 | @item +@r{, }- | |
6641 | Addition and subtraction on integral and floating-point types, or union | |
6642 | and difference on set types. | |
6643 | ||
6644 | @item * | |
6645 | Multiplication on integral and floating-point types, or set intersection | |
6646 | on set types. | |
6647 | ||
6648 | @item / | |
6649 | Division on floating-point types, or symmetric set difference on set | |
6650 | types. Same precedence as @code{*}. | |
6651 | ||
6652 | @item DIV@r{, }MOD | |
6653 | Integer division and remainder. Defined on integral types. Same | |
6654 | precedence as @code{*}. | |
6655 | ||
6656 | @item - | |
6657 | Negative. Defined on @code{INTEGER} and @code{REAL} data. | |
6658 | ||
6659 | @item ^ | |
6660 | Pointer dereferencing. Defined on pointer types. | |
6661 | ||
6662 | @item NOT | |
6663 | Boolean negation. Defined on boolean types. Same precedence as | |
6664 | @code{^}. | |
6665 | ||
6666 | @item . | |
6667 | @code{RECORD} field selector. Defined on @code{RECORD} data. Same | |
6668 | precedence as @code{^}. | |
6669 | ||
6670 | @item [] | |
6671 | Array indexing. Defined on @code{ARRAY} data. Same precedence as @code{^}. | |
6672 | ||
6673 | @item () | |
6674 | Procedure argument list. Defined on @code{PROCEDURE} objects. Same precedence | |
6675 | as @code{^}. | |
6676 | ||
6677 | @item ::@r{, }. | |
6678 | @value{GDBN} and Modula-2 scope operators. | |
6679 | @end table | |
6680 | ||
6681 | @quotation | |
6682 | @emph{Warning:} Sets and their operations are not yet supported, so @value{GDBN} | |
6683 | treats the use of the operator @code{IN}, or the use of operators | |
6684 | @code{+}, @code{-}, @code{*}, @code{/}, @code{=}, , @code{<>}, @code{#}, | |
6685 | @code{<=}, and @code{>=} on sets as an error. | |
6686 | @end quotation | |
6687 | ||
6688 | @cindex Modula-2 built-ins | |
6d2ebf8b | 6689 | @node Built-In Func/Proc |
c906108c SS |
6690 | @subsubsection Built-in functions and procedures |
6691 | ||
6692 | Modula-2 also makes available several built-in procedures and functions. | |
6693 | In describing these, the following metavariables are used: | |
6694 | ||
6695 | @table @var | |
6696 | ||
6697 | @item a | |
6698 | represents an @code{ARRAY} variable. | |
6699 | ||
6700 | @item c | |
6701 | represents a @code{CHAR} constant or variable. | |
6702 | ||
6703 | @item i | |
6704 | represents a variable or constant of integral type. | |
6705 | ||
6706 | @item m | |
6707 | represents an identifier that belongs to a set. Generally used in the | |
6708 | same function with the metavariable @var{s}. The type of @var{s} should | |
6709 | be @code{SET OF @var{mtype}} (where @var{mtype} is the type of @var{m}). | |
6710 | ||
6711 | @item n | |
6712 | represents a variable or constant of integral or floating-point type. | |
6713 | ||
6714 | @item r | |
6715 | represents a variable or constant of floating-point type. | |
6716 | ||
6717 | @item t | |
6718 | represents a type. | |
6719 | ||
6720 | @item v | |
6721 | represents a variable. | |
6722 | ||
6723 | @item x | |
6724 | represents a variable or constant of one of many types. See the | |
6725 | explanation of the function for details. | |
6726 | @end table | |
6727 | ||
6728 | All Modula-2 built-in procedures also return a result, described below. | |
6729 | ||
6730 | @table @code | |
6731 | @item ABS(@var{n}) | |
6732 | Returns the absolute value of @var{n}. | |
6733 | ||
6734 | @item CAP(@var{c}) | |
6735 | If @var{c} is a lower case letter, it returns its upper case | |
c3f6f71d | 6736 | equivalent, otherwise it returns its argument. |
c906108c SS |
6737 | |
6738 | @item CHR(@var{i}) | |
6739 | Returns the character whose ordinal value is @var{i}. | |
6740 | ||
6741 | @item DEC(@var{v}) | |
c3f6f71d | 6742 | Decrements the value in the variable @var{v} by one. Returns the new value. |
c906108c SS |
6743 | |
6744 | @item DEC(@var{v},@var{i}) | |
6745 | Decrements the value in the variable @var{v} by @var{i}. Returns the | |
6746 | new value. | |
6747 | ||
6748 | @item EXCL(@var{m},@var{s}) | |
6749 | Removes the element @var{m} from the set @var{s}. Returns the new | |
6750 | set. | |
6751 | ||
6752 | @item FLOAT(@var{i}) | |
6753 | Returns the floating point equivalent of the integer @var{i}. | |
6754 | ||
6755 | @item HIGH(@var{a}) | |
6756 | Returns the index of the last member of @var{a}. | |
6757 | ||
6758 | @item INC(@var{v}) | |
c3f6f71d | 6759 | Increments the value in the variable @var{v} by one. Returns the new value. |
c906108c SS |
6760 | |
6761 | @item INC(@var{v},@var{i}) | |
6762 | Increments the value in the variable @var{v} by @var{i}. Returns the | |
6763 | new value. | |
6764 | ||
6765 | @item INCL(@var{m},@var{s}) | |
6766 | Adds the element @var{m} to the set @var{s} if it is not already | |
6767 | there. Returns the new set. | |
6768 | ||
6769 | @item MAX(@var{t}) | |
6770 | Returns the maximum value of the type @var{t}. | |
6771 | ||
6772 | @item MIN(@var{t}) | |
6773 | Returns the minimum value of the type @var{t}. | |
6774 | ||
6775 | @item ODD(@var{i}) | |
6776 | Returns boolean TRUE if @var{i} is an odd number. | |
6777 | ||
6778 | @item ORD(@var{x}) | |
6779 | Returns the ordinal value of its argument. For example, the ordinal | |
c3f6f71d JM |
6780 | value of a character is its @sc{ascii} value (on machines supporting the |
6781 | @sc{ascii} character set). @var{x} must be of an ordered type, which include | |
c906108c SS |
6782 | integral, character and enumerated types. |
6783 | ||
6784 | @item SIZE(@var{x}) | |
6785 | Returns the size of its argument. @var{x} can be a variable or a type. | |
6786 | ||
6787 | @item TRUNC(@var{r}) | |
6788 | Returns the integral part of @var{r}. | |
6789 | ||
6790 | @item VAL(@var{t},@var{i}) | |
6791 | Returns the member of the type @var{t} whose ordinal value is @var{i}. | |
6792 | @end table | |
6793 | ||
6794 | @quotation | |
6795 | @emph{Warning:} Sets and their operations are not yet supported, so | |
6796 | @value{GDBN} treats the use of procedures @code{INCL} and @code{EXCL} as | |
6797 | an error. | |
6798 | @end quotation | |
6799 | ||
6800 | @cindex Modula-2 constants | |
6d2ebf8b | 6801 | @node M2 Constants |
c906108c SS |
6802 | @subsubsection Constants |
6803 | ||
6804 | @value{GDBN} allows you to express the constants of Modula-2 in the following | |
6805 | ways: | |
6806 | ||
6807 | @itemize @bullet | |
6808 | ||
6809 | @item | |
6810 | Integer constants are simply a sequence of digits. When used in an | |
6811 | expression, a constant is interpreted to be type-compatible with the | |
6812 | rest of the expression. Hexadecimal integers are specified by a | |
6813 | trailing @samp{H}, and octal integers by a trailing @samp{B}. | |
6814 | ||
6815 | @item | |
6816 | Floating point constants appear as a sequence of digits, followed by a | |
6817 | decimal point and another sequence of digits. An optional exponent can | |
6818 | then be specified, in the form @samp{E@r{[}+@r{|}-@r{]}@var{nnn}}, where | |
6819 | @samp{@r{[}+@r{|}-@r{]}@var{nnn}} is the desired exponent. All of the | |
6820 | digits of the floating point constant must be valid decimal (base 10) | |
6821 | digits. | |
6822 | ||
6823 | @item | |
6824 | Character constants consist of a single character enclosed by a pair of | |
6825 | like quotes, either single (@code{'}) or double (@code{"}). They may | |
c3f6f71d | 6826 | also be expressed by their ordinal value (their @sc{ascii} value, usually) |
c906108c SS |
6827 | followed by a @samp{C}. |
6828 | ||
6829 | @item | |
6830 | String constants consist of a sequence of characters enclosed by a | |
6831 | pair of like quotes, either single (@code{'}) or double (@code{"}). | |
6832 | Escape sequences in the style of C are also allowed. @xref{C | |
6833 | Constants, ,C and C++ constants}, for a brief explanation of escape | |
6834 | sequences. | |
6835 | ||
6836 | @item | |
6837 | Enumerated constants consist of an enumerated identifier. | |
6838 | ||
6839 | @item | |
6840 | Boolean constants consist of the identifiers @code{TRUE} and | |
6841 | @code{FALSE}. | |
6842 | ||
6843 | @item | |
6844 | Pointer constants consist of integral values only. | |
6845 | ||
6846 | @item | |
6847 | Set constants are not yet supported. | |
6848 | @end itemize | |
6849 | ||
6d2ebf8b | 6850 | @node M2 Defaults |
c906108c SS |
6851 | @subsubsection Modula-2 defaults |
6852 | @cindex Modula-2 defaults | |
6853 | ||
6854 | If type and range checking are set automatically by @value{GDBN}, they | |
6855 | both default to @code{on} whenever the working language changes to | |
d4f3574e | 6856 | Modula-2. This happens regardless of whether you or @value{GDBN} |
c906108c SS |
6857 | selected the working language. |
6858 | ||
6859 | If you allow @value{GDBN} to set the language automatically, then entering | |
6860 | code compiled from a file whose name ends with @file{.mod} sets the | |
d4f3574e | 6861 | working language to Modula-2. @xref{Automatically, ,Having @value{GDBN} set |
c906108c SS |
6862 | the language automatically}, for further details. |
6863 | ||
6d2ebf8b | 6864 | @node Deviations |
c906108c SS |
6865 | @subsubsection Deviations from standard Modula-2 |
6866 | @cindex Modula-2, deviations from | |
6867 | ||
6868 | A few changes have been made to make Modula-2 programs easier to debug. | |
6869 | This is done primarily via loosening its type strictness: | |
6870 | ||
6871 | @itemize @bullet | |
6872 | @item | |
6873 | Unlike in standard Modula-2, pointer constants can be formed by | |
6874 | integers. This allows you to modify pointer variables during | |
6875 | debugging. (In standard Modula-2, the actual address contained in a | |
6876 | pointer variable is hidden from you; it can only be modified | |
6877 | through direct assignment to another pointer variable or expression that | |
6878 | returned a pointer.) | |
6879 | ||
6880 | @item | |
6881 | C escape sequences can be used in strings and characters to represent | |
6882 | non-printable characters. @value{GDBN} prints out strings with these | |
6883 | escape sequences embedded. Single non-printable characters are | |
6884 | printed using the @samp{CHR(@var{nnn})} format. | |
6885 | ||
6886 | @item | |
6887 | The assignment operator (@code{:=}) returns the value of its right-hand | |
6888 | argument. | |
6889 | ||
6890 | @item | |
6891 | All built-in procedures both modify @emph{and} return their argument. | |
6892 | @end itemize | |
6893 | ||
6d2ebf8b | 6894 | @node M2 Checks |
c906108c SS |
6895 | @subsubsection Modula-2 type and range checks |
6896 | @cindex Modula-2 checks | |
6897 | ||
6898 | @quotation | |
6899 | @emph{Warning:} in this release, @value{GDBN} does not yet perform type or | |
6900 | range checking. | |
6901 | @end quotation | |
6902 | @c FIXME remove warning when type/range checks added | |
6903 | ||
6904 | @value{GDBN} considers two Modula-2 variables type equivalent if: | |
6905 | ||
6906 | @itemize @bullet | |
6907 | @item | |
6908 | They are of types that have been declared equivalent via a @code{TYPE | |
6909 | @var{t1} = @var{t2}} statement | |
6910 | ||
6911 | @item | |
6912 | They have been declared on the same line. (Note: This is true of the | |
6913 | @sc{gnu} Modula-2 compiler, but it may not be true of other compilers.) | |
6914 | @end itemize | |
6915 | ||
6916 | As long as type checking is enabled, any attempt to combine variables | |
6917 | whose types are not equivalent is an error. | |
6918 | ||
6919 | Range checking is done on all mathematical operations, assignment, array | |
6920 | index bounds, and all built-in functions and procedures. | |
6921 | ||
6d2ebf8b | 6922 | @node M2 Scope |
c906108c SS |
6923 | @subsubsection The scope operators @code{::} and @code{.} |
6924 | @cindex scope | |
41afff9a | 6925 | @cindex @code{.}, Modula-2 scope operator |
c906108c SS |
6926 | @cindex colon, doubled as scope operator |
6927 | @ifinfo | |
41afff9a | 6928 | @vindex colon-colon@r{, in Modula-2} |
c906108c SS |
6929 | @c Info cannot handle :: but TeX can. |
6930 | @end ifinfo | |
6931 | @iftex | |
41afff9a | 6932 | @vindex ::@r{, in Modula-2} |
c906108c SS |
6933 | @end iftex |
6934 | ||
6935 | There are a few subtle differences between the Modula-2 scope operator | |
6936 | (@code{.}) and the @value{GDBN} scope operator (@code{::}). The two have | |
6937 | similar syntax: | |
6938 | ||
6939 | @example | |
6940 | ||
6941 | @var{module} . @var{id} | |
6942 | @var{scope} :: @var{id} | |
6943 | @end example | |
6944 | ||
6945 | @noindent | |
6946 | where @var{scope} is the name of a module or a procedure, | |
6947 | @var{module} the name of a module, and @var{id} is any declared | |
6948 | identifier within your program, except another module. | |
6949 | ||
6950 | Using the @code{::} operator makes @value{GDBN} search the scope | |
6951 | specified by @var{scope} for the identifier @var{id}. If it is not | |
6952 | found in the specified scope, then @value{GDBN} searches all scopes | |
6953 | enclosing the one specified by @var{scope}. | |
6954 | ||
6955 | Using the @code{.} operator makes @value{GDBN} search the current scope for | |
6956 | the identifier specified by @var{id} that was imported from the | |
6957 | definition module specified by @var{module}. With this operator, it is | |
6958 | an error if the identifier @var{id} was not imported from definition | |
6959 | module @var{module}, or if @var{id} is not an identifier in | |
6960 | @var{module}. | |
6961 | ||
6d2ebf8b | 6962 | @node GDB/M2 |
c906108c SS |
6963 | @subsubsection @value{GDBN} and Modula-2 |
6964 | ||
6965 | Some @value{GDBN} commands have little use when debugging Modula-2 programs. | |
6966 | Five subcommands of @code{set print} and @code{show print} apply | |
6967 | specifically to C and C++: @samp{vtbl}, @samp{demangle}, | |
6968 | @samp{asm-demangle}, @samp{object}, and @samp{union}. The first four | |
6969 | apply to C++, and the last to the C @code{union} type, which has no direct | |
6970 | analogue in Modula-2. | |
6971 | ||
6972 | The @code{@@} operator (@pxref{Expressions, ,Expressions}), while available | |
d4f3574e | 6973 | with any language, is not useful with Modula-2. Its |
c906108c SS |
6974 | intent is to aid the debugging of @dfn{dynamic arrays}, which cannot be |
6975 | created in Modula-2 as they can in C or C++. However, because an | |
6976 | address can be specified by an integral constant, the construct | |
d4f3574e | 6977 | @samp{@{@var{type}@}@var{adrexp}} is still useful. |
c906108c SS |
6978 | |
6979 | @cindex @code{#} in Modula-2 | |
6980 | In @value{GDBN} scripts, the Modula-2 inequality operator @code{#} is | |
6981 | interpreted as the beginning of a comment. Use @code{<>} instead. | |
c906108c | 6982 | |
6d2ebf8b | 6983 | @node Chill |
cce74817 JM |
6984 | @subsection Chill |
6985 | ||
6986 | The extensions made to @value{GDBN} to support Chill only support output | |
d4f3574e | 6987 | from the @sc{gnu} Chill compiler. Other Chill compilers are not currently |
cce74817 JM |
6988 | supported, and attempting to debug executables produced by them is most |
6989 | likely to give an error as @value{GDBN} reads in the executable's symbol | |
6990 | table. | |
6991 | ||
d4f3574e SS |
6992 | @c This used to say "... following Chill related topics ...", but since |
6993 | @c menus are not shown in the printed manual, it would look awkward. | |
6994 | This section covers the Chill related topics and the features | |
cce74817 JM |
6995 | of @value{GDBN} which support these topics. |
6996 | ||
6997 | @menu | |
104c1213 JM |
6998 | * How modes are displayed:: How modes are displayed |
6999 | * Locations:: Locations and their accesses | |
cce74817 | 7000 | * Values and their Operations:: Values and their Operations |
5d161b24 | 7001 | * Chill type and range checks:: |
53a5351d | 7002 | * Chill defaults:: |
cce74817 JM |
7003 | @end menu |
7004 | ||
6d2ebf8b | 7005 | @node How modes are displayed |
cce74817 JM |
7006 | @subsubsection How modes are displayed |
7007 | ||
7008 | The Chill Datatype- (Mode) support of @value{GDBN} is directly related | |
d4f3574e | 7009 | with the functionality of the @sc{gnu} Chill compiler, and therefore deviates |
cce74817 JM |
7010 | slightly from the standard specification of the Chill language. The |
7011 | provided modes are: | |
d4f3574e SS |
7012 | |
7013 | @c FIXME: this @table's contents effectively disable @code by using @r | |
7014 | @c on every @item. So why does it need @code? | |
cce74817 JM |
7015 | @table @code |
7016 | @item @r{@emph{Discrete modes:}} | |
7017 | @itemize @bullet | |
7018 | @item | |
7019 | @emph{Integer Modes} which are predefined by @code{BYTE, UBYTE, INT, | |
7020 | UINT, LONG, ULONG}, | |
7021 | @item | |
5d161b24 | 7022 | @emph{Boolean Mode} which is predefined by @code{BOOL}, |
cce74817 | 7023 | @item |
5d161b24 | 7024 | @emph{Character Mode} which is predefined by @code{CHAR}, |
cce74817 JM |
7025 | @item |
7026 | @emph{Set Mode} which is displayed by the keyword @code{SET}. | |
7027 | @smallexample | |
7028 | (@value{GDBP}) ptype x | |
7029 | type = SET (karli = 10, susi = 20, fritzi = 100) | |
7030 | @end smallexample | |
7031 | If the type is an unnumbered set the set element values are omitted. | |
7032 | @item | |
6d2ebf8b SS |
7033 | @emph{Range Mode} which is displayed by |
7034 | @smallexample | |
7035 | @code{type = <basemode>(<lower bound> : <upper bound>)} | |
7036 | @end smallexample | |
7037 | where @code{<lower bound>, <upper bound>} can be of any discrete literal | |
7038 | expression (e.g. set element names). | |
cce74817 JM |
7039 | @end itemize |
7040 | ||
7041 | @item @r{@emph{Powerset Mode:}} | |
7042 | A Powerset Mode is displayed by the keyword @code{POWERSET} followed by | |
d4f3574e | 7043 | the member mode of the powerset. The member mode can be any discrete mode. |
cce74817 JM |
7044 | @smallexample |
7045 | (@value{GDBP}) ptype x | |
7046 | type = POWERSET SET (egon, hugo, otto) | |
7047 | @end smallexample | |
7048 | ||
7049 | @item @r{@emph{Reference Modes:}} | |
7050 | @itemize @bullet | |
7051 | @item | |
d4f3574e | 7052 | @emph{Bound Reference Mode} which is displayed by the keyword @code{REF} |
cce74817 JM |
7053 | followed by the mode name to which the reference is bound. |
7054 | @item | |
7055 | @emph{Free Reference Mode} which is displayed by the keyword @code{PTR}. | |
7056 | @end itemize | |
7057 | ||
7058 | @item @r{@emph{Procedure mode}} | |
7059 | The procedure mode is displayed by @code{type = PROC(<parameter list>) | |
7060 | <return mode> EXCEPTIONS (<exception list>)}. The @code{<parameter | |
d4f3574e SS |
7061 | list>} is a list of the parameter modes. @code{<return mode>} indicates |
7062 | the mode of the result of the procedure if any. The exceptionlist lists | |
cce74817 JM |
7063 | all possible exceptions which can be raised by the procedure. |
7064 | ||
7065 | @ignore | |
7066 | @item @r{@emph{Instance mode}} | |
7067 | The instance mode is represented by a structure, which has a static | |
5d161b24 | 7068 | type, and is therefore not really of interest. |
cce74817 JM |
7069 | @end ignore |
7070 | ||
5d161b24 | 7071 | @item @r{@emph{Synchronization Modes:}} |
cce74817 JM |
7072 | @itemize @bullet |
7073 | @item | |
6d2ebf8b SS |
7074 | @emph{Event Mode} which is displayed by |
7075 | @smallexample | |
7076 | @code{EVENT (<event length>)} | |
7077 | @end smallexample | |
cce74817 JM |
7078 | where @code{(<event length>)} is optional. |
7079 | @item | |
6d2ebf8b SS |
7080 | @emph{Buffer Mode} which is displayed by |
7081 | @smallexample | |
7082 | @code{BUFFER (<buffer length>)<buffer element mode>} | |
7083 | @end smallexample | |
7084 | where @code{(<buffer length>)} is optional. | |
cce74817 JM |
7085 | @end itemize |
7086 | ||
5d161b24 | 7087 | @item @r{@emph{Timing Modes:}} |
cce74817 JM |
7088 | @itemize @bullet |
7089 | @item | |
7090 | @emph{Duration Mode} which is predefined by @code{DURATION} | |
7091 | @item | |
7092 | @emph{Absolute Time Mode} which is predefined by @code{TIME} | |
7093 | @end itemize | |
7094 | ||
7095 | @item @r{@emph{Real Modes:}} | |
7096 | Real Modes are predefined with @code{REAL} and @code{LONG_REAL}. | |
7097 | ||
7098 | @item @r{@emph{String Modes:}} | |
7099 | @itemize @bullet | |
7100 | @item | |
6d2ebf8b SS |
7101 | @emph{Character String Mode} which is displayed by |
7102 | @smallexample | |
7103 | @code{CHARS(<string length>)} | |
7104 | @end smallexample | |
7105 | followed by the keyword @code{VARYING} if the String Mode is a varying | |
7106 | mode | |
cce74817 | 7107 | @item |
6d2ebf8b SS |
7108 | @emph{Bit String Mode} which is displayed by |
7109 | @smallexample | |
7110 | @code{BOOLS(<string | |
7111 | length>)} | |
7112 | @end smallexample | |
cce74817 JM |
7113 | @end itemize |
7114 | ||
7115 | @item @r{@emph{Array Mode:}} | |
7116 | The Array Mode is displayed by the keyword @code{ARRAY(<range>)} | |
7117 | followed by the element mode (which may in turn be an array mode). | |
7118 | @smallexample | |
7119 | (@value{GDBP}) ptype x | |
5d161b24 DB |
7120 | type = ARRAY (1:42) |
7121 | ARRAY (1:20) | |
cce74817 JM |
7122 | SET (karli = 10, susi = 20, fritzi = 100) |
7123 | @end smallexample | |
7124 | ||
5d161b24 | 7125 | @item @r{@emph{Structure Mode}} |
cce74817 | 7126 | The Structure mode is displayed by the keyword @code{STRUCT(<field |
d4f3574e SS |
7127 | list>)}. The @code{<field list>} consists of names and modes of fields |
7128 | of the structure. Variant structures have the keyword @code{CASE <field> | |
7129 | OF <variant fields> ESAC} in their field list. Since the current version | |
cce74817 JM |
7130 | of the GNU Chill compiler doesn't implement tag processing (no runtime |
7131 | checks of variant fields, and therefore no debugging info), the output | |
7132 | always displays all variant fields. | |
7133 | @smallexample | |
7134 | (@value{GDBP}) ptype str | |
7135 | type = STRUCT ( | |
7136 | as x, | |
7137 | bs x, | |
7138 | CASE bs OF | |
7139 | (karli): | |
7140 | cs a | |
7141 | (ott): | |
7142 | ds x | |
7143 | ESAC | |
7144 | ) | |
7145 | @end smallexample | |
7146 | @end table | |
7147 | ||
6d2ebf8b | 7148 | @node Locations |
cce74817 JM |
7149 | @subsubsection Locations and their accesses |
7150 | ||
7151 | A location in Chill is an object which can contain values. | |
7152 | ||
7153 | A value of a location is generally accessed by the (declared) name of | |
d4f3574e SS |
7154 | the location. The output conforms to the specification of values in |
7155 | Chill programs. How values are specified | |
7156 | is the topic of the next section, @ref{Values and their Operations}. | |
cce74817 JM |
7157 | |
7158 | The pseudo-location @code{RESULT} (or @code{result}) can be used to | |
7159 | display or change the result of a currently-active procedure: | |
d4f3574e | 7160 | |
cce74817 JM |
7161 | @smallexample |
7162 | set result := EXPR | |
7163 | @end smallexample | |
d4f3574e SS |
7164 | |
7165 | @noindent | |
7166 | This does the same as the Chill action @code{RESULT EXPR} (which | |
c3f6f71d | 7167 | is not available in @value{GDBN}). |
cce74817 JM |
7168 | |
7169 | Values of reference mode locations are printed by @code{PTR(<hex | |
7170 | value>)} in case of a free reference mode, and by @code{(REF <reference | |
d4f3574e | 7171 | mode>) (<hex-value>)} in case of a bound reference. @code{<hex value>} |
cce74817 JM |
7172 | represents the address where the reference points to. To access the |
7173 | value of the location referenced by the pointer, use the dereference | |
d4f3574e | 7174 | operator @samp{->}. |
cce74817 | 7175 | |
6d2ebf8b SS |
7176 | Values of procedure mode locations are displayed by |
7177 | @smallexample | |
7178 | @code{@{ PROC | |
cce74817 | 7179 | (<argument modes> ) <return mode> @} <address> <name of procedure |
6d2ebf8b SS |
7180 | location>} |
7181 | @end smallexample | |
7182 | @code{<argument modes>} is a list of modes according to the parameter | |
7183 | specification of the procedure and @code{<address>} shows the address of | |
7184 | the entry point. | |
cce74817 JM |
7185 | |
7186 | @ignore | |
7187 | Locations of instance modes are displayed just like a structure with two | |
7188 | fields specifying the @emph{process type} and the @emph{copy number} of | |
7189 | the investigated instance location@footnote{This comes from the current | |
d4f3574e SS |
7190 | implementation of instances. They are implemented as a structure (no |
7191 | na). The output should be something like @code{[<name of the process>; | |
7192 | <instance number>]}.}. The field names are @code{__proc_type} and | |
cce74817 JM |
7193 | @code{__proc_copy}. |
7194 | ||
7195 | Locations of synchronization modes are displayed like a structure with | |
7196 | the field name @code{__event_data} in case of a event mode location, and | |
7197 | like a structure with the field @code{__buffer_data} in case of a buffer | |
7198 | mode location (refer to previous paragraph). | |
7199 | ||
7200 | Structure Mode locations are printed by @code{[.<field name>: <value>, | |
d4f3574e | 7201 | ...]}. The @code{<field name>} corresponds to the structure mode |
cce74817 | 7202 | definition and the layout of @code{<value>} varies depending of the mode |
d4f3574e SS |
7203 | of the field. If the investigated structure mode location is of variant |
7204 | structure mode, the variant parts of the structure are enclosed in curled | |
7205 | braces (@samp{@{@}}). Fields enclosed by @samp{@{,@}} are residing | |
cce74817 | 7206 | on the same memory location and represent the current values of the |
d4f3574e | 7207 | memory location in their specific modes. Since no tag processing is done |
cce74817 | 7208 | all variants are displayed. A variant field is printed by |
d4f3574e | 7209 | @code{(<variant name>) = .<field name>: <value>}. (who implements the |
cce74817 JM |
7210 | stuff ???) |
7211 | @smallexample | |
7212 | (@value{GDBP}) print str1 $4 = [.as: 0, .bs: karli, .<TAG>: { (karli) = | |
7213 | [.cs: []], (susi) = [.ds: susi]}] | |
7214 | @end smallexample | |
7215 | @end ignore | |
7216 | ||
7217 | Substructures of string mode-, array mode- or structure mode-values | |
7218 | (e.g. array slices, fields of structure locations) are accessed using | |
d4f3574e SS |
7219 | certain operations which are described in the next section, @ref{Values |
7220 | and their Operations}. | |
cce74817 JM |
7221 | |
7222 | A location value may be interpreted as having a different mode using the | |
d4f3574e SS |
7223 | location conversion. This mode conversion is written as @code{<mode |
7224 | name>(<location>)}. The user has to consider that the sizes of the modes | |
7225 | have to be equal otherwise an error occurs. Furthermore, no range | |
7226 | checking of the location against the destination mode is performed, and | |
cce74817 | 7227 | therefore the result can be quite confusing. |
d4f3574e | 7228 | |
cce74817 JM |
7229 | @smallexample |
7230 | (@value{GDBP}) print int (s(3 up 4)) XXX TO be filled in !! XXX | |
7231 | @end smallexample | |
7232 | ||
6d2ebf8b | 7233 | @node Values and their Operations |
cce74817 JM |
7234 | @subsubsection Values and their Operations |
7235 | ||
7236 | Values are used to alter locations, to investigate complex structures in | |
7237 | more detail or to filter relevant information out of a large amount of | |
d4f3574e SS |
7238 | data. There are several (mode dependent) operations defined which enable |
7239 | such investigations. These operations are not only applicable to | |
cce74817 | 7240 | constant values but also to locations, which can become quite useful |
d4f3574e | 7241 | when debugging complex structures. During parsing the command line |
cce74817 JM |
7242 | (e.g. evaluating an expression) @value{GDBN} treats location names as |
7243 | the values behind these locations. | |
7244 | ||
d4f3574e | 7245 | This section describes how values have to be specified and which |
cce74817 JM |
7246 | operations are legal to be used with such values. |
7247 | ||
7248 | @table @code | |
7249 | @item Literal Values | |
d4f3574e SS |
7250 | Literal values are specified in the same manner as in @sc{gnu} Chill programs. |
7251 | For detailed specification refer to the @sc{gnu} Chill implementation Manual | |
cce74817 | 7252 | chapter 1.5. |
d4f3574e SS |
7253 | @c FIXME: if the Chill Manual is a Texinfo documents, the above should |
7254 | @c be converted to a @ref. | |
cce74817 | 7255 | |
5d161b24 | 7256 | @ignore |
cce74817 JM |
7257 | @itemize @bullet |
7258 | @item | |
7259 | @emph{Integer Literals} are specified in the same manner as in Chill | |
d4f3574e | 7260 | programs (refer to the Chill Standard z200/88 chpt 5.2.4.2) |
cce74817 JM |
7261 | @item |
7262 | @emph{Boolean Literals} are defined by @code{TRUE} and @code{FALSE}. | |
7263 | @item | |
7264 | @emph{Character Literals} are defined by @code{'<character>'}. (e.g. | |
7265 | @code{'M'}) | |
7266 | @item | |
7267 | @emph{Set Literals} are defined by a name which was specified in a set | |
d4f3574e SS |
7268 | mode. The value delivered by a Set Literal is the set value. This is |
7269 | comparable to an enumeration in C/C++ language. | |
cce74817 | 7270 | @item |
d4f3574e | 7271 | @emph{Emptiness Literal} is predefined by @code{NULL}. The value of the |
cce74817 | 7272 | emptiness literal delivers either the empty reference value, the empty |
5d161b24 | 7273 | procedure value or the empty instance value. |
cce74817 JM |
7274 | |
7275 | @item | |
7276 | @emph{Character String Literals} are defined by a sequence of characters | |
d4f3574e | 7277 | enclosed in single- or double quotes. If a single- or double quote has |
cce74817 JM |
7278 | to be part of the string literal it has to be stuffed (specified twice). |
7279 | @item | |
7280 | @emph{Bitstring Literals} are specified in the same manner as in Chill | |
7281 | programs (refer z200/88 chpt 5.2.4.8). | |
7282 | @item | |
7283 | @emph{Floating point literals} are specified in the same manner as in | |
d4f3574e | 7284 | (gnu-)Chill programs (refer @sc{gnu} Chill implementation Manual chapter 1.5). |
cce74817 JM |
7285 | @end itemize |
7286 | @end ignore | |
7287 | ||
7288 | @item Tuple Values | |
7289 | A tuple is specified by @code{<mode name>[<tuple>]}, where @code{<mode | |
d4f3574e | 7290 | name>} can be omitted if the mode of the tuple is unambiguous. This |
cce74817 JM |
7291 | unambiguity is derived from the context of a evaluated expression. |
7292 | @code{<tuple>} can be one of the following: | |
d4f3574e | 7293 | |
cce74817 JM |
7294 | @itemize @bullet |
7295 | @item @emph{Powerset Tuple} | |
7296 | @item @emph{Array Tuple} | |
7297 | @item @emph{Structure Tuple} | |
7298 | Powerset tuples, array tuples and structure tuples are specified in the | |
d4f3574e | 7299 | same manner as in Chill programs refer to z200/88 chpt 5.2.5. |
cce74817 JM |
7300 | @end itemize |
7301 | ||
7302 | @item String Element Value | |
6d2ebf8b SS |
7303 | A string element value is specified by |
7304 | @smallexample | |
7305 | @code{<string value>(<index>)} | |
7306 | @end smallexample | |
d4f3574e | 7307 | where @code{<index>} is a integer expression. It delivers a character |
cce74817 JM |
7308 | value which is equivalent to the character indexed by @code{<index>} in |
7309 | the string. | |
7310 | ||
7311 | @item String Slice Value | |
7312 | A string slice value is specified by @code{<string value>(<slice | |
7313 | spec>)}, where @code{<slice spec>} can be either a range of integer | |
7314 | expressions or specified by @code{<start expr> up <size>}. | |
7315 | @code{<size>} denotes the number of elements which the slice contains. | |
7316 | The delivered value is a string value, which is part of the specified | |
7317 | string. | |
7318 | ||
7319 | @item Array Element Values | |
7320 | An array element value is specified by @code{<array value>(<expr>)} and | |
7321 | delivers a array element value of the mode of the specified array. | |
7322 | ||
7323 | @item Array Slice Values | |
7324 | An array slice is specified by @code{<array value>(<slice spec>)}, where | |
7325 | @code{<slice spec>} can be either a range specified by expressions or by | |
d4f3574e SS |
7326 | @code{<start expr> up <size>}. @code{<size>} denotes the number of |
7327 | arrayelements the slice contains. The delivered value is an array value | |
cce74817 JM |
7328 | which is part of the specified array. |
7329 | ||
7330 | @item Structure Field Values | |
7331 | A structure field value is derived by @code{<structure value>.<field | |
d4f3574e SS |
7332 | name>}, where @code{<field name>} indicates the name of a field specified |
7333 | in the mode definition of the structure. The mode of the delivered value | |
cce74817 JM |
7334 | corresponds to this mode definition in the structure definition. |
7335 | ||
7336 | @item Procedure Call Value | |
7337 | The procedure call value is derived from the return value of the | |
7338 | procedure@footnote{If a procedure call is used for instance in an | |
7339 | expression, then this procedure is called with all its side | |
d4f3574e | 7340 | effects. This can lead to confusing results if used carelessly.}. |
cce74817 | 7341 | |
d4f3574e | 7342 | Values of duration mode locations are represented by @code{ULONG} literals. |
cce74817 | 7343 | |
6d2ebf8b SS |
7344 | Values of time mode locations appear as |
7345 | @smallexample | |
7346 | @code{TIME(<secs>:<nsecs>)} | |
7347 | @end smallexample | |
7348 | ||
cce74817 JM |
7349 | |
7350 | @ignore | |
7351 | This is not implemented yet: | |
7352 | @item Built-in Value | |
7353 | @noindent | |
7354 | The following built in functions are provided: | |
d4f3574e | 7355 | |
cce74817 JM |
7356 | @table @code |
7357 | @item @code{ADDR()} | |
7358 | @item @code{NUM()} | |
7359 | @item @code{PRED()} | |
7360 | @item @code{SUCC()} | |
7361 | @item @code{ABS()} | |
7362 | @item @code{CARD()} | |
7363 | @item @code{MAX()} | |
7364 | @item @code{MIN()} | |
7365 | @item @code{SIZE()} | |
7366 | @item @code{UPPER()} | |
7367 | @item @code{LOWER()} | |
7368 | @item @code{LENGTH()} | |
7369 | @item @code{SIN()} | |
7370 | @item @code{COS()} | |
7371 | @item @code{TAN()} | |
7372 | @item @code{ARCSIN()} | |
7373 | @item @code{ARCCOS()} | |
7374 | @item @code{ARCTAN()} | |
7375 | @item @code{EXP()} | |
7376 | @item @code{LN()} | |
7377 | @item @code{LOG()} | |
7378 | @item @code{SQRT()} | |
7379 | @end table | |
7380 | ||
7381 | For a detailed description refer to the GNU Chill implementation manual | |
7382 | chapter 1.6. | |
7383 | @end ignore | |
7384 | ||
7385 | @item Zero-adic Operator Value | |
7386 | The zero-adic operator value is derived from the instance value for the | |
7387 | current active process. | |
7388 | ||
7389 | @item Expression Values | |
7390 | The value delivered by an expression is the result of the evaluation of | |
d4f3574e | 7391 | the specified expression. If there are error conditions (mode |
cce74817 | 7392 | incompatibility, etc.) the evaluation of expressions is aborted with a |
d4f3574e | 7393 | corresponding error message. Expressions may be parenthesised which |
cce74817 | 7394 | causes the evaluation of this expression before any other expression |
d4f3574e | 7395 | which uses the result of the parenthesised expression. The following |
cce74817 | 7396 | operators are supported by @value{GDBN}: |
d4f3574e | 7397 | |
cce74817 JM |
7398 | @table @code |
7399 | @item @code{OR, ORIF, XOR} | |
d4f3574e SS |
7400 | @itemx @code{AND, ANDIF} |
7401 | @itemx @code{NOT} | |
cce74817 | 7402 | Logical operators defined over operands of boolean mode. |
d4f3574e | 7403 | |
cce74817 JM |
7404 | @item @code{=, /=} |
7405 | Equality and inequality operators defined over all modes. | |
d4f3574e | 7406 | |
cce74817 | 7407 | @item @code{>, >=} |
d4f3574e | 7408 | @itemx @code{<, <=} |
cce74817 | 7409 | Relational operators defined over predefined modes. |
d4f3574e | 7410 | |
cce74817 | 7411 | @item @code{+, -} |
d4f3574e | 7412 | @itemx @code{*, /, MOD, REM} |
cce74817 | 7413 | Arithmetic operators defined over predefined modes. |
d4f3574e | 7414 | |
cce74817 JM |
7415 | @item @code{-} |
7416 | Change sign operator. | |
d4f3574e | 7417 | |
cce74817 JM |
7418 | @item @code{//} |
7419 | String concatenation operator. | |
d4f3574e | 7420 | |
cce74817 JM |
7421 | @item @code{()} |
7422 | String repetition operator. | |
d4f3574e | 7423 | |
cce74817 JM |
7424 | @item @code{->} |
7425 | Referenced location operator which can be used either to take the | |
7426 | address of a location (@code{->loc}), or to dereference a reference | |
7427 | location (@code{loc->}). | |
d4f3574e | 7428 | |
cce74817 | 7429 | @item @code{OR, XOR} |
d4f3574e SS |
7430 | @itemx @code{AND} |
7431 | @itemx @code{NOT} | |
cce74817 | 7432 | Powerset and bitstring operators. |
d4f3574e | 7433 | |
cce74817 | 7434 | @item @code{>, >=} |
d4f3574e | 7435 | @itemx @code{<, <=} |
cce74817 | 7436 | Powerset inclusion operators. |
d4f3574e | 7437 | |
cce74817 JM |
7438 | @item @code{IN} |
7439 | Membership operator. | |
7440 | @end table | |
7441 | @end table | |
7442 | ||
6d2ebf8b | 7443 | @node Chill type and range checks |
cce74817 JM |
7444 | @subsubsection Chill type and range checks |
7445 | ||
7446 | @value{GDBN} considers two Chill variables mode equivalent if the sizes | |
d4f3574e | 7447 | of the two modes are equal. This rule applies recursively to more |
cce74817 | 7448 | complex datatypes which means that complex modes are treated |
d4f3574e | 7449 | equivalent if all element modes (which also can be complex modes like |
cce74817 JM |
7450 | structures, arrays, etc.) have the same size. |
7451 | ||
7452 | Range checking is done on all mathematical operations, assignment, array | |
7453 | index bounds and all built in procedures. | |
7454 | ||
7455 | Strong type checks are forced using the @value{GDBN} command @code{set | |
d4f3574e | 7456 | check strong}. This enforces strong type and range checks on all |
cce74817 JM |
7457 | operations where Chill constructs are used (expressions, built in |
7458 | functions, etc.) in respect to the semantics as defined in the z.200 | |
7459 | language specification. | |
7460 | ||
cce74817 JM |
7461 | All checks can be disabled by the @value{GDBN} command @code{set check |
7462 | off}. | |
7463 | ||
5d161b24 | 7464 | @ignore |
53a5351d | 7465 | @c Deviations from the Chill Standard Z200/88 |
cce74817 JM |
7466 | see last paragraph ? |
7467 | @end ignore | |
7468 | ||
6d2ebf8b | 7469 | @node Chill defaults |
cce74817 JM |
7470 | @subsubsection Chill defaults |
7471 | ||
7472 | If type and range checking are set automatically by @value{GDBN}, they | |
7473 | both default to @code{on} whenever the working language changes to | |
d4f3574e | 7474 | Chill. This happens regardless of whether you or @value{GDBN} |
cce74817 JM |
7475 | selected the working language. |
7476 | ||
7477 | If you allow @value{GDBN} to set the language automatically, then entering | |
7478 | code compiled from a file whose name ends with @file{.ch} sets the | |
d4f3574e | 7479 | working language to Chill. @xref{Automatically, ,Having @value{GDBN} set |
cce74817 JM |
7480 | the language automatically}, for further details. |
7481 | ||
6d2ebf8b | 7482 | @node Symbols |
c906108c SS |
7483 | @chapter Examining the Symbol Table |
7484 | ||
d4f3574e | 7485 | The commands described in this chapter allow you to inquire about the |
c906108c SS |
7486 | symbols (names of variables, functions and types) defined in your |
7487 | program. This information is inherent in the text of your program and | |
7488 | does not change as your program executes. @value{GDBN} finds it in your | |
7489 | program's symbol table, in the file indicated when you started @value{GDBN} | |
7490 | (@pxref{File Options, ,Choosing files}), or by one of the | |
7491 | file-management commands (@pxref{Files, ,Commands to specify files}). | |
7492 | ||
7493 | @cindex symbol names | |
7494 | @cindex names of symbols | |
7495 | @cindex quoting names | |
7496 | Occasionally, you may need to refer to symbols that contain unusual | |
7497 | characters, which @value{GDBN} ordinarily treats as word delimiters. The | |
7498 | most frequent case is in referring to static variables in other | |
7499 | source files (@pxref{Variables,,Program variables}). File names | |
7500 | are recorded in object files as debugging symbols, but @value{GDBN} would | |
7501 | ordinarily parse a typical file name, like @file{foo.c}, as the three words | |
7502 | @samp{foo} @samp{.} @samp{c}. To allow @value{GDBN} to recognize | |
7503 | @samp{foo.c} as a single symbol, enclose it in single quotes; for example, | |
7504 | ||
7505 | @example | |
7506 | p 'foo.c'::x | |
7507 | @end example | |
7508 | ||
7509 | @noindent | |
7510 | looks up the value of @code{x} in the scope of the file @file{foo.c}. | |
7511 | ||
7512 | @table @code | |
7513 | @kindex info address | |
7514 | @item info address @var{symbol} | |
7515 | Describe where the data for @var{symbol} is stored. For a register | |
7516 | variable, this says which register it is kept in. For a non-register | |
7517 | local variable, this prints the stack-frame offset at which the variable | |
7518 | is always stored. | |
7519 | ||
7520 | Note the contrast with @samp{print &@var{symbol}}, which does not work | |
7521 | at all for a register variable, and for a stack local variable prints | |
7522 | the exact address of the current instantiation of the variable. | |
7523 | ||
7524 | @kindex whatis | |
d4f3574e SS |
7525 | @item whatis @var{expr} |
7526 | Print the data type of expression @var{expr}. @var{expr} is not | |
c906108c SS |
7527 | actually evaluated, and any side-effecting operations (such as |
7528 | assignments or function calls) inside it do not take place. | |
7529 | @xref{Expressions, ,Expressions}. | |
7530 | ||
7531 | @item whatis | |
7532 | Print the data type of @code{$}, the last value in the value history. | |
7533 | ||
7534 | @kindex ptype | |
7535 | @item ptype @var{typename} | |
7536 | Print a description of data type @var{typename}. @var{typename} may be | |
7a292a7a SS |
7537 | the name of a type, or for C code it may have the form @samp{class |
7538 | @var{class-name}}, @samp{struct @var{struct-tag}}, @samp{union | |
7539 | @var{union-tag}} or @samp{enum @var{enum-tag}}. | |
c906108c | 7540 | |
d4f3574e | 7541 | @item ptype @var{expr} |
c906108c | 7542 | @itemx ptype |
d4f3574e | 7543 | Print a description of the type of expression @var{expr}. @code{ptype} |
c906108c SS |
7544 | differs from @code{whatis} by printing a detailed description, instead |
7545 | of just the name of the type. | |
7546 | ||
7547 | For example, for this variable declaration: | |
7548 | ||
7549 | @example | |
7550 | struct complex @{double real; double imag;@} v; | |
7551 | @end example | |
7552 | ||
7553 | @noindent | |
7554 | the two commands give this output: | |
7555 | ||
7556 | @example | |
7557 | @group | |
7558 | (@value{GDBP}) whatis v | |
7559 | type = struct complex | |
7560 | (@value{GDBP}) ptype v | |
7561 | type = struct complex @{ | |
7562 | double real; | |
7563 | double imag; | |
7564 | @} | |
7565 | @end group | |
7566 | @end example | |
7567 | ||
7568 | @noindent | |
7569 | As with @code{whatis}, using @code{ptype} without an argument refers to | |
7570 | the type of @code{$}, the last value in the value history. | |
7571 | ||
7572 | @kindex info types | |
7573 | @item info types @var{regexp} | |
7574 | @itemx info types | |
d4f3574e | 7575 | Print a brief description of all types whose names match @var{regexp} |
c906108c SS |
7576 | (or all types in your program, if you supply no argument). Each |
7577 | complete typename is matched as though it were a complete line; thus, | |
7578 | @samp{i type value} gives information on all types in your program whose | |
d4f3574e | 7579 | names include the string @code{value}, but @samp{i type ^value$} gives |
c906108c SS |
7580 | information only on types whose complete name is @code{value}. |
7581 | ||
7582 | This command differs from @code{ptype} in two ways: first, like | |
7583 | @code{whatis}, it does not print a detailed description; second, it | |
7584 | lists all source files where a type is defined. | |
7585 | ||
7586 | @kindex info source | |
7587 | @item info source | |
7588 | Show the name of the current source file---that is, the source file for | |
7589 | the function containing the current point of execution---and the language | |
7590 | it was written in. | |
7591 | ||
7592 | @kindex info sources | |
7593 | @item info sources | |
7594 | Print the names of all source files in your program for which there is | |
7595 | debugging information, organized into two lists: files whose symbols | |
7596 | have already been read, and files whose symbols will be read when needed. | |
7597 | ||
7598 | @kindex info functions | |
7599 | @item info functions | |
7600 | Print the names and data types of all defined functions. | |
7601 | ||
7602 | @item info functions @var{regexp} | |
7603 | Print the names and data types of all defined functions | |
7604 | whose names contain a match for regular expression @var{regexp}. | |
7605 | Thus, @samp{info fun step} finds all functions whose names | |
7606 | include @code{step}; @samp{info fun ^step} finds those whose names | |
7607 | start with @code{step}. | |
7608 | ||
7609 | @kindex info variables | |
7610 | @item info variables | |
7611 | Print the names and data types of all variables that are declared | |
7612 | outside of functions (i.e., excluding local variables). | |
7613 | ||
7614 | @item info variables @var{regexp} | |
7615 | Print the names and data types of all variables (except for local | |
7616 | variables) whose names contain a match for regular expression | |
7617 | @var{regexp}. | |
7618 | ||
7619 | @ignore | |
7620 | This was never implemented. | |
7621 | @kindex info methods | |
7622 | @item info methods | |
7623 | @itemx info methods @var{regexp} | |
7624 | The @code{info methods} command permits the user to examine all defined | |
7625 | methods within C++ program, or (with the @var{regexp} argument) a | |
7626 | specific set of methods found in the various C++ classes. Many | |
7627 | C++ classes provide a large number of methods. Thus, the output | |
7628 | from the @code{ptype} command can be overwhelming and hard to use. The | |
7629 | @code{info-methods} command filters the methods, printing only those | |
7630 | which match the regular-expression @var{regexp}. | |
7631 | @end ignore | |
7632 | ||
c906108c SS |
7633 | @cindex reloading symbols |
7634 | Some systems allow individual object files that make up your program to | |
7a292a7a SS |
7635 | be replaced without stopping and restarting your program. For example, |
7636 | in VxWorks you can simply recompile a defective object file and keep on | |
7637 | running. If you are running on one of these systems, you can allow | |
7638 | @value{GDBN} to reload the symbols for automatically relinked modules: | |
c906108c SS |
7639 | |
7640 | @table @code | |
7641 | @kindex set symbol-reloading | |
7642 | @item set symbol-reloading on | |
7643 | Replace symbol definitions for the corresponding source file when an | |
7644 | object file with a particular name is seen again. | |
7645 | ||
7646 | @item set symbol-reloading off | |
6d2ebf8b SS |
7647 | Do not replace symbol definitions when encountering object files of the |
7648 | same name more than once. This is the default state; if you are not | |
7649 | running on a system that permits automatic relinking of modules, you | |
7650 | should leave @code{symbol-reloading} off, since otherwise @value{GDBN} | |
7651 | may discard symbols when linking large programs, that may contain | |
7652 | several modules (from different directories or libraries) with the same | |
7653 | name. | |
c906108c SS |
7654 | |
7655 | @kindex show symbol-reloading | |
7656 | @item show symbol-reloading | |
7657 | Show the current @code{on} or @code{off} setting. | |
7658 | @end table | |
c906108c | 7659 | |
c906108c SS |
7660 | @kindex set opaque-type-resolution |
7661 | @item set opaque-type-resolution on | |
7662 | Tell @value{GDBN} to resolve opaque types. An opaque type is a type | |
7663 | declared as a pointer to a @code{struct}, @code{class}, or | |
7664 | @code{union}---for example, @code{struct MyType *}---that is used in one | |
7665 | source file although the full declaration of @code{struct MyType} is in | |
7666 | another source file. The default is on. | |
7667 | ||
7668 | A change in the setting of this subcommand will not take effect until | |
7669 | the next time symbols for a file are loaded. | |
7670 | ||
7671 | @item set opaque-type-resolution off | |
7672 | Tell @value{GDBN} not to resolve opaque types. In this case, the type | |
7673 | is printed as follows: | |
7674 | @smallexample | |
7675 | @{<no data fields>@} | |
7676 | @end smallexample | |
7677 | ||
7678 | @kindex show opaque-type-resolution | |
7679 | @item show opaque-type-resolution | |
7680 | Show whether opaque types are resolved or not. | |
c906108c SS |
7681 | |
7682 | @kindex maint print symbols | |
7683 | @cindex symbol dump | |
7684 | @kindex maint print psymbols | |
7685 | @cindex partial symbol dump | |
7686 | @item maint print symbols @var{filename} | |
7687 | @itemx maint print psymbols @var{filename} | |
7688 | @itemx maint print msymbols @var{filename} | |
7689 | Write a dump of debugging symbol data into the file @var{filename}. | |
7690 | These commands are used to debug the @value{GDBN} symbol-reading code. Only | |
7691 | symbols with debugging data are included. If you use @samp{maint print | |
7692 | symbols}, @value{GDBN} includes all the symbols for which it has already | |
7693 | collected full details: that is, @var{filename} reflects symbols for | |
7694 | only those files whose symbols @value{GDBN} has read. You can use the | |
7695 | command @code{info sources} to find out which files these are. If you | |
7696 | use @samp{maint print psymbols} instead, the dump shows information about | |
7697 | symbols that @value{GDBN} only knows partially---that is, symbols defined in | |
7698 | files that @value{GDBN} has skimmed, but not yet read completely. Finally, | |
7699 | @samp{maint print msymbols} dumps just the minimal symbol information | |
7700 | required for each object file from which @value{GDBN} has read some symbols. | |
7701 | @xref{Files, ,Commands to specify files}, for a discussion of how | |
7702 | @value{GDBN} reads symbols (in the description of @code{symbol-file}). | |
7703 | @end table | |
7704 | ||
6d2ebf8b | 7705 | @node Altering |
c906108c SS |
7706 | @chapter Altering Execution |
7707 | ||
7708 | Once you think you have found an error in your program, you might want to | |
7709 | find out for certain whether correcting the apparent error would lead to | |
7710 | correct results in the rest of the run. You can find the answer by | |
7711 | experiment, using the @value{GDBN} features for altering execution of the | |
7712 | program. | |
7713 | ||
7714 | For example, you can store new values into variables or memory | |
7a292a7a SS |
7715 | locations, give your program a signal, restart it at a different |
7716 | address, or even return prematurely from a function. | |
c906108c SS |
7717 | |
7718 | @menu | |
7719 | * Assignment:: Assignment to variables | |
7720 | * Jumping:: Continuing at a different address | |
c906108c | 7721 | * Signaling:: Giving your program a signal |
c906108c SS |
7722 | * Returning:: Returning from a function |
7723 | * Calling:: Calling your program's functions | |
7724 | * Patching:: Patching your program | |
7725 | @end menu | |
7726 | ||
6d2ebf8b | 7727 | @node Assignment |
c906108c SS |
7728 | @section Assignment to variables |
7729 | ||
7730 | @cindex assignment | |
7731 | @cindex setting variables | |
7732 | To alter the value of a variable, evaluate an assignment expression. | |
7733 | @xref{Expressions, ,Expressions}. For example, | |
7734 | ||
7735 | @example | |
7736 | print x=4 | |
7737 | @end example | |
7738 | ||
7739 | @noindent | |
7740 | stores the value 4 into the variable @code{x}, and then prints the | |
5d161b24 | 7741 | value of the assignment expression (which is 4). |
c906108c SS |
7742 | @xref{Languages, ,Using @value{GDBN} with Different Languages}, for more |
7743 | information on operators in supported languages. | |
c906108c SS |
7744 | |
7745 | @kindex set variable | |
7746 | @cindex variables, setting | |
7747 | If you are not interested in seeing the value of the assignment, use the | |
7748 | @code{set} command instead of the @code{print} command. @code{set} is | |
7749 | really the same as @code{print} except that the expression's value is | |
7750 | not printed and is not put in the value history (@pxref{Value History, | |
7751 | ,Value history}). The expression is evaluated only for its effects. | |
7752 | ||
c906108c SS |
7753 | If the beginning of the argument string of the @code{set} command |
7754 | appears identical to a @code{set} subcommand, use the @code{set | |
7755 | variable} command instead of just @code{set}. This command is identical | |
7756 | to @code{set} except for its lack of subcommands. For example, if your | |
7757 | program has a variable @code{width}, you get an error if you try to set | |
7758 | a new value with just @samp{set width=13}, because @value{GDBN} has the | |
7759 | command @code{set width}: | |
7760 | ||
7761 | @example | |
7762 | (@value{GDBP}) whatis width | |
7763 | type = double | |
7764 | (@value{GDBP}) p width | |
7765 | $4 = 13 | |
7766 | (@value{GDBP}) set width=47 | |
7767 | Invalid syntax in expression. | |
7768 | @end example | |
7769 | ||
7770 | @noindent | |
7771 | The invalid expression, of course, is @samp{=47}. In | |
7772 | order to actually set the program's variable @code{width}, use | |
7773 | ||
7774 | @example | |
7775 | (@value{GDBP}) set var width=47 | |
7776 | @end example | |
53a5351d | 7777 | |
c906108c SS |
7778 | Because the @code{set} command has many subcommands that can conflict |
7779 | with the names of program variables, it is a good idea to use the | |
7780 | @code{set variable} command instead of just @code{set}. For example, if | |
7781 | your program has a variable @code{g}, you run into problems if you try | |
7782 | to set a new value with just @samp{set g=4}, because @value{GDBN} has | |
7783 | the command @code{set gnutarget}, abbreviated @code{set g}: | |
7784 | ||
7785 | @example | |
7786 | @group | |
7787 | (@value{GDBP}) whatis g | |
7788 | type = double | |
7789 | (@value{GDBP}) p g | |
7790 | $1 = 1 | |
7791 | (@value{GDBP}) set g=4 | |
2df3850c | 7792 | (@value{GDBP}) p g |
c906108c SS |
7793 | $2 = 1 |
7794 | (@value{GDBP}) r | |
7795 | The program being debugged has been started already. | |
7796 | Start it from the beginning? (y or n) y | |
7797 | Starting program: /home/smith/cc_progs/a.out | |
6d2ebf8b SS |
7798 | "/home/smith/cc_progs/a.out": can't open to read symbols: |
7799 | Invalid bfd target. | |
c906108c SS |
7800 | (@value{GDBP}) show g |
7801 | The current BFD target is "=4". | |
7802 | @end group | |
7803 | @end example | |
7804 | ||
7805 | @noindent | |
7806 | The program variable @code{g} did not change, and you silently set the | |
7807 | @code{gnutarget} to an invalid value. In order to set the variable | |
7808 | @code{g}, use | |
7809 | ||
7810 | @example | |
7811 | (@value{GDBP}) set var g=4 | |
7812 | @end example | |
c906108c SS |
7813 | |
7814 | @value{GDBN} allows more implicit conversions in assignments than C; you can | |
7815 | freely store an integer value into a pointer variable or vice versa, | |
7816 | and you can convert any structure to any other structure that is the | |
7817 | same length or shorter. | |
7818 | @comment FIXME: how do structs align/pad in these conversions? | |
7819 | @comment /[email protected] 18dec1990 | |
7820 | ||
7821 | To store values into arbitrary places in memory, use the @samp{@{@dots{}@}} | |
7822 | construct to generate a value of specified type at a specified address | |
7823 | (@pxref{Expressions, ,Expressions}). For example, @code{@{int@}0x83040} refers | |
7824 | to memory location @code{0x83040} as an integer (which implies a certain size | |
7825 | and representation in memory), and | |
7826 | ||
7827 | @example | |
7828 | set @{int@}0x83040 = 4 | |
7829 | @end example | |
7830 | ||
7831 | @noindent | |
7832 | stores the value 4 into that memory location. | |
7833 | ||
6d2ebf8b | 7834 | @node Jumping |
c906108c SS |
7835 | @section Continuing at a different address |
7836 | ||
7837 | Ordinarily, when you continue your program, you do so at the place where | |
7838 | it stopped, with the @code{continue} command. You can instead continue at | |
7839 | an address of your own choosing, with the following commands: | |
7840 | ||
7841 | @table @code | |
7842 | @kindex jump | |
7843 | @item jump @var{linespec} | |
7844 | Resume execution at line @var{linespec}. Execution stops again | |
7845 | immediately if there is a breakpoint there. @xref{List, ,Printing | |
7846 | source lines}, for a description of the different forms of | |
7847 | @var{linespec}. It is common practice to use the @code{tbreak} command | |
7848 | in conjunction with @code{jump}. @xref{Set Breaks, ,Setting | |
7849 | breakpoints}. | |
7850 | ||
7851 | The @code{jump} command does not change the current stack frame, or | |
7852 | the stack pointer, or the contents of any memory location or any | |
7853 | register other than the program counter. If line @var{linespec} is in | |
7854 | a different function from the one currently executing, the results may | |
7855 | be bizarre if the two functions expect different patterns of arguments or | |
7856 | of local variables. For this reason, the @code{jump} command requests | |
7857 | confirmation if the specified line is not in the function currently | |
7858 | executing. However, even bizarre results are predictable if you are | |
7859 | well acquainted with the machine-language code of your program. | |
7860 | ||
7861 | @item jump *@var{address} | |
7862 | Resume execution at the instruction at address @var{address}. | |
7863 | @end table | |
7864 | ||
c906108c | 7865 | @c Doesn't work on HP-UX; have to set $pcoqh and $pcoqt. |
53a5351d JM |
7866 | On many systems, you can get much the same effect as the @code{jump} |
7867 | command by storing a new value into the register @code{$pc}. The | |
7868 | difference is that this does not start your program running; it only | |
7869 | changes the address of where it @emph{will} run when you continue. For | |
7870 | example, | |
c906108c SS |
7871 | |
7872 | @example | |
7873 | set $pc = 0x485 | |
7874 | @end example | |
7875 | ||
7876 | @noindent | |
7877 | makes the next @code{continue} command or stepping command execute at | |
7878 | address @code{0x485}, rather than at the address where your program stopped. | |
7879 | @xref{Continuing and Stepping, ,Continuing and stepping}. | |
c906108c SS |
7880 | |
7881 | The most common occasion to use the @code{jump} command is to back | |
7882 | up---perhaps with more breakpoints set---over a portion of a program | |
7883 | that has already executed, in order to examine its execution in more | |
7884 | detail. | |
7885 | ||
c906108c | 7886 | @c @group |
6d2ebf8b | 7887 | @node Signaling |
c906108c SS |
7888 | @section Giving your program a signal |
7889 | ||
7890 | @table @code | |
7891 | @kindex signal | |
7892 | @item signal @var{signal} | |
7893 | Resume execution where your program stopped, but immediately give it the | |
7894 | signal @var{signal}. @var{signal} can be the name or the number of a | |
7895 | signal. For example, on many systems @code{signal 2} and @code{signal | |
7896 | SIGINT} are both ways of sending an interrupt signal. | |
7897 | ||
7898 | Alternatively, if @var{signal} is zero, continue execution without | |
7899 | giving a signal. This is useful when your program stopped on account of | |
7900 | a signal and would ordinary see the signal when resumed with the | |
7901 | @code{continue} command; @samp{signal 0} causes it to resume without a | |
7902 | signal. | |
7903 | ||
7904 | @code{signal} does not repeat when you press @key{RET} a second time | |
7905 | after executing the command. | |
7906 | @end table | |
7907 | @c @end group | |
7908 | ||
7909 | Invoking the @code{signal} command is not the same as invoking the | |
7910 | @code{kill} utility from the shell. Sending a signal with @code{kill} | |
7911 | causes @value{GDBN} to decide what to do with the signal depending on | |
7912 | the signal handling tables (@pxref{Signals}). The @code{signal} command | |
7913 | passes the signal directly to your program. | |
7914 | ||
c906108c | 7915 | |
6d2ebf8b | 7916 | @node Returning |
c906108c SS |
7917 | @section Returning from a function |
7918 | ||
7919 | @table @code | |
7920 | @cindex returning from a function | |
7921 | @kindex return | |
7922 | @item return | |
7923 | @itemx return @var{expression} | |
7924 | You can cancel execution of a function call with the @code{return} | |
7925 | command. If you give an | |
7926 | @var{expression} argument, its value is used as the function's return | |
7927 | value. | |
7928 | @end table | |
7929 | ||
7930 | When you use @code{return}, @value{GDBN} discards the selected stack frame | |
7931 | (and all frames within it). You can think of this as making the | |
7932 | discarded frame return prematurely. If you wish to specify a value to | |
7933 | be returned, give that value as the argument to @code{return}. | |
7934 | ||
7935 | This pops the selected stack frame (@pxref{Selection, ,Selecting a | |
7936 | frame}), and any other frames inside of it, leaving its caller as the | |
7937 | innermost remaining frame. That frame becomes selected. The | |
7938 | specified value is stored in the registers used for returning values | |
7939 | of functions. | |
7940 | ||
7941 | The @code{return} command does not resume execution; it leaves the | |
7942 | program stopped in the state that would exist if the function had just | |
7943 | returned. In contrast, the @code{finish} command (@pxref{Continuing | |
7944 | and Stepping, ,Continuing and stepping}) resumes execution until the | |
7945 | selected stack frame returns naturally. | |
7946 | ||
6d2ebf8b | 7947 | @node Calling |
c906108c SS |
7948 | @section Calling program functions |
7949 | ||
7950 | @cindex calling functions | |
7951 | @kindex call | |
7952 | @table @code | |
7953 | @item call @var{expr} | |
7954 | Evaluate the expression @var{expr} without displaying @code{void} | |
7955 | returned values. | |
7956 | @end table | |
7957 | ||
7958 | You can use this variant of the @code{print} command if you want to | |
7959 | execute a function from your program, but without cluttering the output | |
5d161b24 DB |
7960 | with @code{void} returned values. If the result is not void, it |
7961 | is printed and saved in the value history. | |
c906108c | 7962 | |
c906108c SS |
7963 | For the A29K, a user-controlled variable @code{call_scratch_address}, |
7964 | specifies the location of a scratch area to be used when @value{GDBN} | |
7965 | calls a function in the target. This is necessary because the usual | |
7966 | method of putting the scratch area on the stack does not work in systems | |
7967 | that have separate instruction and data spaces. | |
c906108c | 7968 | |
6d2ebf8b | 7969 | @node Patching |
c906108c | 7970 | @section Patching programs |
7a292a7a | 7971 | |
c906108c SS |
7972 | @cindex patching binaries |
7973 | @cindex writing into executables | |
c906108c | 7974 | @cindex writing into corefiles |
c906108c | 7975 | |
7a292a7a SS |
7976 | By default, @value{GDBN} opens the file containing your program's |
7977 | executable code (or the corefile) read-only. This prevents accidental | |
7978 | alterations to machine code; but it also prevents you from intentionally | |
7979 | patching your program's binary. | |
c906108c SS |
7980 | |
7981 | If you'd like to be able to patch the binary, you can specify that | |
7982 | explicitly with the @code{set write} command. For example, you might | |
7983 | want to turn on internal debugging flags, or even to make emergency | |
7984 | repairs. | |
7985 | ||
7986 | @table @code | |
7987 | @kindex set write | |
7988 | @item set write on | |
7989 | @itemx set write off | |
7a292a7a SS |
7990 | If you specify @samp{set write on}, @value{GDBN} opens executable and |
7991 | core files for both reading and writing; if you specify @samp{set write | |
c906108c SS |
7992 | off} (the default), @value{GDBN} opens them read-only. |
7993 | ||
7994 | If you have already loaded a file, you must load it again (using the | |
7a292a7a SS |
7995 | @code{exec-file} or @code{core-file} command) after changing @code{set |
7996 | write}, for your new setting to take effect. | |
c906108c SS |
7997 | |
7998 | @item show write | |
7999 | @kindex show write | |
7a292a7a SS |
8000 | Display whether executable files and core files are opened for writing |
8001 | as well as reading. | |
c906108c SS |
8002 | @end table |
8003 | ||
6d2ebf8b | 8004 | @node GDB Files |
c906108c SS |
8005 | @chapter @value{GDBN} Files |
8006 | ||
7a292a7a SS |
8007 | @value{GDBN} needs to know the file name of the program to be debugged, |
8008 | both in order to read its symbol table and in order to start your | |
8009 | program. To debug a core dump of a previous run, you must also tell | |
8010 | @value{GDBN} the name of the core dump file. | |
c906108c SS |
8011 | |
8012 | @menu | |
8013 | * Files:: Commands to specify files | |
8014 | * Symbol Errors:: Errors reading symbol files | |
8015 | @end menu | |
8016 | ||
6d2ebf8b | 8017 | @node Files |
c906108c | 8018 | @section Commands to specify files |
c906108c | 8019 | |
7a292a7a | 8020 | @cindex symbol table |
c906108c | 8021 | @cindex core dump file |
7a292a7a SS |
8022 | |
8023 | You may want to specify executable and core dump file names. The usual | |
8024 | way to do this is at start-up time, using the arguments to | |
8025 | @value{GDBN}'s start-up commands (@pxref{Invocation, , Getting In and | |
8026 | Out of @value{GDBN}}). | |
c906108c SS |
8027 | |
8028 | Occasionally it is necessary to change to a different file during a | |
8029 | @value{GDBN} session. Or you may run @value{GDBN} and forget to specify | |
8030 | a file you want to use. In these situations the @value{GDBN} commands | |
8031 | to specify new files are useful. | |
8032 | ||
8033 | @table @code | |
8034 | @cindex executable file | |
8035 | @kindex file | |
8036 | @item file @var{filename} | |
8037 | Use @var{filename} as the program to be debugged. It is read for its | |
8038 | symbols and for the contents of pure memory. It is also the program | |
8039 | executed when you use the @code{run} command. If you do not specify a | |
5d161b24 DB |
8040 | directory and the file is not found in the @value{GDBN} working directory, |
8041 | @value{GDBN} uses the environment variable @code{PATH} as a list of | |
8042 | directories to search, just as the shell does when looking for a program | |
8043 | to run. You can change the value of this variable, for both @value{GDBN} | |
c906108c SS |
8044 | and your program, using the @code{path} command. |
8045 | ||
6d2ebf8b | 8046 | On systems with memory-mapped files, an auxiliary file named |
c906108c SS |
8047 | @file{@var{filename}.syms} may hold symbol table information for |
8048 | @var{filename}. If so, @value{GDBN} maps in the symbol table from | |
8049 | @file{@var{filename}.syms}, starting up more quickly. See the | |
8050 | descriptions of the file options @samp{-mapped} and @samp{-readnow} | |
8051 | (available on the command line, and with the commands @code{file}, | |
5d161b24 | 8052 | @code{symbol-file}, or @code{add-symbol-file}, described below), |
c906108c | 8053 | for more information. |
c906108c SS |
8054 | |
8055 | @item file | |
8056 | @code{file} with no argument makes @value{GDBN} discard any information it | |
8057 | has on both executable file and the symbol table. | |
8058 | ||
8059 | @kindex exec-file | |
8060 | @item exec-file @r{[} @var{filename} @r{]} | |
8061 | Specify that the program to be run (but not the symbol table) is found | |
8062 | in @var{filename}. @value{GDBN} searches the environment variable @code{PATH} | |
8063 | if necessary to locate your program. Omitting @var{filename} means to | |
8064 | discard information on the executable file. | |
8065 | ||
8066 | @kindex symbol-file | |
8067 | @item symbol-file @r{[} @var{filename} @r{]} | |
8068 | Read symbol table information from file @var{filename}. @code{PATH} is | |
8069 | searched when necessary. Use the @code{file} command to get both symbol | |
8070 | table and program to run from the same file. | |
8071 | ||
8072 | @code{symbol-file} with no argument clears out @value{GDBN} information on your | |
8073 | program's symbol table. | |
8074 | ||
5d161b24 | 8075 | The @code{symbol-file} command causes @value{GDBN} to forget the contents |
c906108c SS |
8076 | of its convenience variables, the value history, and all breakpoints and |
8077 | auto-display expressions. This is because they may contain pointers to | |
8078 | the internal data recording symbols and data types, which are part of | |
8079 | the old symbol table data being discarded inside @value{GDBN}. | |
8080 | ||
8081 | @code{symbol-file} does not repeat if you press @key{RET} again after | |
8082 | executing it once. | |
8083 | ||
8084 | When @value{GDBN} is configured for a particular environment, it | |
8085 | understands debugging information in whatever format is the standard | |
8086 | generated for that environment; you may use either a @sc{gnu} compiler, or | |
8087 | other compilers that adhere to the local conventions. | |
c906108c SS |
8088 | Best results are usually obtained from @sc{gnu} compilers; for example, |
8089 | using @code{@value{GCC}} you can generate debugging information for | |
8090 | optimized code. | |
c906108c SS |
8091 | |
8092 | For most kinds of object files, with the exception of old SVR3 systems | |
8093 | using COFF, the @code{symbol-file} command does not normally read the | |
8094 | symbol table in full right away. Instead, it scans the symbol table | |
8095 | quickly to find which source files and which symbols are present. The | |
8096 | details are read later, one source file at a time, as they are needed. | |
8097 | ||
8098 | The purpose of this two-stage reading strategy is to make @value{GDBN} | |
8099 | start up faster. For the most part, it is invisible except for | |
8100 | occasional pauses while the symbol table details for a particular source | |
8101 | file are being read. (The @code{set verbose} command can turn these | |
8102 | pauses into messages if desired. @xref{Messages/Warnings, ,Optional | |
8103 | warnings and messages}.) | |
8104 | ||
c906108c SS |
8105 | We have not implemented the two-stage strategy for COFF yet. When the |
8106 | symbol table is stored in COFF format, @code{symbol-file} reads the | |
8107 | symbol table data in full right away. Note that ``stabs-in-COFF'' | |
8108 | still does the two-stage strategy, since the debug info is actually | |
8109 | in stabs format. | |
8110 | ||
8111 | @kindex readnow | |
8112 | @cindex reading symbols immediately | |
8113 | @cindex symbols, reading immediately | |
8114 | @kindex mapped | |
8115 | @cindex memory-mapped symbol file | |
8116 | @cindex saving symbol table | |
8117 | @item symbol-file @var{filename} @r{[} -readnow @r{]} @r{[} -mapped @r{]} | |
8118 | @itemx file @var{filename} @r{[} -readnow @r{]} @r{[} -mapped @r{]} | |
8119 | You can override the @value{GDBN} two-stage strategy for reading symbol | |
8120 | tables by using the @samp{-readnow} option with any of the commands that | |
8121 | load symbol table information, if you want to be sure @value{GDBN} has the | |
5d161b24 | 8122 | entire symbol table available. |
c906108c | 8123 | |
c906108c SS |
8124 | If memory-mapped files are available on your system through the |
8125 | @code{mmap} system call, you can use another option, @samp{-mapped}, to | |
8126 | cause @value{GDBN} to write the symbols for your program into a reusable | |
8127 | file. Future @value{GDBN} debugging sessions map in symbol information | |
8128 | from this auxiliary symbol file (if the program has not changed), rather | |
8129 | than spending time reading the symbol table from the executable | |
8130 | program. Using the @samp{-mapped} option has the same effect as | |
8131 | starting @value{GDBN} with the @samp{-mapped} command-line option. | |
8132 | ||
8133 | You can use both options together, to make sure the auxiliary symbol | |
8134 | file has all the symbol information for your program. | |
8135 | ||
8136 | The auxiliary symbol file for a program called @var{myprog} is called | |
8137 | @samp{@var{myprog}.syms}. Once this file exists (so long as it is newer | |
8138 | than the corresponding executable), @value{GDBN} always attempts to use | |
8139 | it when you debug @var{myprog}; no special options or commands are | |
8140 | needed. | |
8141 | ||
8142 | The @file{.syms} file is specific to the host machine where you run | |
8143 | @value{GDBN}. It holds an exact image of the internal @value{GDBN} | |
8144 | symbol table. It cannot be shared across multiple host platforms. | |
c906108c SS |
8145 | |
8146 | @c FIXME: for now no mention of directories, since this seems to be in | |
8147 | @c flux. 13mar1992 status is that in theory GDB would look either in | |
8148 | @c current dir or in same dir as myprog; but issues like competing | |
8149 | @c GDB's, or clutter in system dirs, mean that in practice right now | |
8150 | @c only current dir is used. FFish says maybe a special GDB hierarchy | |
8151 | @c (eg rooted in val of env var GDBSYMS) could exist for mappable symbol | |
8152 | @c files. | |
8153 | ||
8154 | @kindex core | |
8155 | @kindex core-file | |
8156 | @item core-file @r{[} @var{filename} @r{]} | |
8157 | Specify the whereabouts of a core dump file to be used as the ``contents | |
8158 | of memory''. Traditionally, core files contain only some parts of the | |
8159 | address space of the process that generated them; @value{GDBN} can access the | |
8160 | executable file itself for other parts. | |
8161 | ||
8162 | @code{core-file} with no argument specifies that no core file is | |
8163 | to be used. | |
8164 | ||
8165 | Note that the core file is ignored when your program is actually running | |
7a292a7a SS |
8166 | under @value{GDBN}. So, if you have been running your program and you |
8167 | wish to debug a core file instead, you must kill the subprocess in which | |
8168 | the program is running. To do this, use the @code{kill} command | |
c906108c | 8169 | (@pxref{Kill Process, ,Killing the child process}). |
c906108c | 8170 | |
c906108c SS |
8171 | @kindex add-symbol-file |
8172 | @cindex dynamic linking | |
8173 | @item add-symbol-file @var{filename} @var{address} | |
8174 | @itemx add-symbol-file @var{filename} @var{address} @r{[} -readnow @r{]} @r{[} -mapped @r{]} | |
d167840f | 8175 | @itemx add-symbol-file @var{filename} @r{-s}@var{section} @var{address} |
96a2c332 SS |
8176 | The @code{add-symbol-file} command reads additional symbol table |
8177 | information from the file @var{filename}. You would use this command | |
8178 | when @var{filename} has been dynamically loaded (by some other means) | |
8179 | into the program that is running. @var{address} should be the memory | |
8180 | address at which the file has been loaded; @value{GDBN} cannot figure | |
d167840f EZ |
8181 | this out for itself. You can additionally specify an arbitrary number |
8182 | of @samp{@r{-s}@var{section} @var{address}} pairs, to give an explicit | |
8183 | section name and base address for that section. You can specify any | |
8184 | @var{address} as an expression. | |
c906108c SS |
8185 | |
8186 | The symbol table of the file @var{filename} is added to the symbol table | |
8187 | originally read with the @code{symbol-file} command. You can use the | |
96a2c332 SS |
8188 | @code{add-symbol-file} command any number of times; the new symbol data |
8189 | thus read keeps adding to the old. To discard all old symbol data | |
8190 | instead, use the @code{symbol-file} command without any arguments. | |
c906108c SS |
8191 | |
8192 | @code{add-symbol-file} does not repeat if you press @key{RET} after using it. | |
8193 | ||
8194 | You can use the @samp{-mapped} and @samp{-readnow} options just as with | |
8195 | the @code{symbol-file} command, to change how @value{GDBN} manages the symbol | |
8196 | table information for @var{filename}. | |
8197 | ||
8198 | @kindex add-shared-symbol-file | |
8199 | @item add-shared-symbol-file | |
8200 | The @code{add-shared-symbol-file} command can be used only under Harris' CXUX | |
5d161b24 DB |
8201 | operating system for the Motorola 88k. @value{GDBN} automatically looks for |
8202 | shared libraries, however if @value{GDBN} does not find yours, you can run | |
c906108c | 8203 | @code{add-shared-symbol-file}. It takes no arguments. |
c906108c | 8204 | |
c906108c SS |
8205 | @kindex section |
8206 | @item section | |
5d161b24 DB |
8207 | The @code{section} command changes the base address of section SECTION of |
8208 | the exec file to ADDR. This can be used if the exec file does not contain | |
8209 | section addresses, (such as in the a.out format), or when the addresses | |
8210 | specified in the file itself are wrong. Each section must be changed | |
d4f3574e SS |
8211 | separately. The @code{info files} command, described below, lists all |
8212 | the sections and their addresses. | |
c906108c SS |
8213 | |
8214 | @kindex info files | |
8215 | @kindex info target | |
8216 | @item info files | |
8217 | @itemx info target | |
7a292a7a SS |
8218 | @code{info files} and @code{info target} are synonymous; both print the |
8219 | current target (@pxref{Targets, ,Specifying a Debugging Target}), | |
8220 | including the names of the executable and core dump files currently in | |
8221 | use by @value{GDBN}, and the files from which symbols were loaded. The | |
8222 | command @code{help target} lists all possible targets rather than | |
8223 | current ones. | |
8224 | ||
c906108c SS |
8225 | @end table |
8226 | ||
8227 | All file-specifying commands allow both absolute and relative file names | |
8228 | as arguments. @value{GDBN} always converts the file name to an absolute file | |
8229 | name and remembers it that way. | |
8230 | ||
c906108c | 8231 | @cindex shared libraries |
c906108c SS |
8232 | @value{GDBN} supports HP-UX, SunOS, SVr4, Irix 5, and IBM RS/6000 shared |
8233 | libraries. | |
53a5351d | 8234 | |
c906108c SS |
8235 | @value{GDBN} automatically loads symbol definitions from shared libraries |
8236 | when you use the @code{run} command, or when you examine a core file. | |
8237 | (Before you issue the @code{run} command, @value{GDBN} does not understand | |
8238 | references to a function in a shared library, however---unless you are | |
8239 | debugging a core file). | |
53a5351d JM |
8240 | |
8241 | On HP-UX, if the program loads a library explicitly, @value{GDBN} | |
8242 | automatically loads the symbols at the time of the @code{shl_load} call. | |
8243 | ||
c906108c SS |
8244 | @c FIXME: some @value{GDBN} release may permit some refs to undef |
8245 | @c FIXME...symbols---eg in a break cmd---assuming they are from a shared | |
8246 | @c FIXME...lib; check this from time to time when updating manual | |
8247 | ||
8248 | @table @code | |
8249 | @kindex info sharedlibrary | |
8250 | @kindex info share | |
8251 | @item info share | |
8252 | @itemx info sharedlibrary | |
8253 | Print the names of the shared libraries which are currently loaded. | |
8254 | ||
8255 | @kindex sharedlibrary | |
8256 | @kindex share | |
8257 | @item sharedlibrary @var{regex} | |
8258 | @itemx share @var{regex} | |
c906108c SS |
8259 | Load shared object library symbols for files matching a |
8260 | Unix regular expression. | |
8261 | As with files loaded automatically, it only loads shared libraries | |
8262 | required by your program for a core file or after typing @code{run}. If | |
8263 | @var{regex} is omitted all shared libraries required by your program are | |
8264 | loaded. | |
8265 | @end table | |
8266 | ||
53a5351d JM |
8267 | On HP-UX systems, @value{GDBN} detects the loading of a shared library |
8268 | and automatically reads in symbols from the newly loaded library, up to | |
8269 | a threshold that is initially set but that you can modify if you wish. | |
c906108c SS |
8270 | |
8271 | Beyond that threshold, symbols from shared libraries must be explicitly | |
d4f3574e SS |
8272 | loaded. To load these symbols, use the command @code{sharedlibrary |
8273 | @var{filename}}. The base address of the shared library is determined | |
c906108c SS |
8274 | automatically by @value{GDBN} and need not be specified. |
8275 | ||
8276 | To display or set the threshold, use the commands: | |
8277 | ||
8278 | @table @code | |
8279 | @kindex set auto-solib-add | |
8280 | @item set auto-solib-add @var{threshold} | |
8281 | Set the autoloading size threshold, in megabytes. If @var{threshold} is | |
8282 | nonzero, symbols from all shared object libraries will be loaded | |
8283 | automatically when the inferior begins execution or when the dynamic | |
8284 | linker informs @value{GDBN} that a new library has been loaded, until | |
8285 | the symbol table of the program and libraries exceeds this threshold. | |
8286 | Otherwise, symbols must be loaded manually, using the | |
8287 | @code{sharedlibrary} command. The default threshold is 100 megabytes. | |
8288 | ||
8289 | @kindex show auto-solib-add | |
8290 | @item show auto-solib-add | |
8291 | Display the current autoloading size threshold, in megabytes. | |
8292 | @end table | |
c906108c | 8293 | |
6d2ebf8b | 8294 | @node Symbol Errors |
c906108c SS |
8295 | @section Errors reading symbol files |
8296 | ||
8297 | While reading a symbol file, @value{GDBN} occasionally encounters problems, | |
8298 | such as symbol types it does not recognize, or known bugs in compiler | |
8299 | output. By default, @value{GDBN} does not notify you of such problems, since | |
8300 | they are relatively common and primarily of interest to people | |
8301 | debugging compilers. If you are interested in seeing information | |
8302 | about ill-constructed symbol tables, you can either ask @value{GDBN} to print | |
8303 | only one message about each such type of problem, no matter how many | |
8304 | times the problem occurs; or you can ask @value{GDBN} to print more messages, | |
8305 | to see how many times the problems occur, with the @code{set | |
8306 | complaints} command (@pxref{Messages/Warnings, ,Optional warnings and | |
8307 | messages}). | |
8308 | ||
8309 | The messages currently printed, and their meanings, include: | |
8310 | ||
8311 | @table @code | |
8312 | @item inner block not inside outer block in @var{symbol} | |
8313 | ||
8314 | The symbol information shows where symbol scopes begin and end | |
8315 | (such as at the start of a function or a block of statements). This | |
8316 | error indicates that an inner scope block is not fully contained | |
8317 | in its outer scope blocks. | |
8318 | ||
8319 | @value{GDBN} circumvents the problem by treating the inner block as if it had | |
8320 | the same scope as the outer block. In the error message, @var{symbol} | |
8321 | may be shown as ``@code{(don't know)}'' if the outer block is not a | |
8322 | function. | |
8323 | ||
8324 | @item block at @var{address} out of order | |
8325 | ||
8326 | The symbol information for symbol scope blocks should occur in | |
8327 | order of increasing addresses. This error indicates that it does not | |
8328 | do so. | |
8329 | ||
8330 | @value{GDBN} does not circumvent this problem, and has trouble | |
8331 | locating symbols in the source file whose symbols it is reading. (You | |
8332 | can often determine what source file is affected by specifying | |
8333 | @code{set verbose on}. @xref{Messages/Warnings, ,Optional warnings and | |
8334 | messages}.) | |
8335 | ||
8336 | @item bad block start address patched | |
8337 | ||
8338 | The symbol information for a symbol scope block has a start address | |
8339 | smaller than the address of the preceding source line. This is known | |
8340 | to occur in the SunOS 4.1.1 (and earlier) C compiler. | |
8341 | ||
8342 | @value{GDBN} circumvents the problem by treating the symbol scope block as | |
8343 | starting on the previous source line. | |
8344 | ||
8345 | @item bad string table offset in symbol @var{n} | |
8346 | ||
8347 | @cindex foo | |
8348 | Symbol number @var{n} contains a pointer into the string table which is | |
8349 | larger than the size of the string table. | |
8350 | ||
8351 | @value{GDBN} circumvents the problem by considering the symbol to have the | |
8352 | name @code{foo}, which may cause other problems if many symbols end up | |
8353 | with this name. | |
8354 | ||
8355 | @item unknown symbol type @code{0x@var{nn}} | |
8356 | ||
7a292a7a SS |
8357 | The symbol information contains new data types that @value{GDBN} does |
8358 | not yet know how to read. @code{0x@var{nn}} is the symbol type of the | |
d4f3574e | 8359 | uncomprehended information, in hexadecimal. |
c906108c | 8360 | |
7a292a7a SS |
8361 | @value{GDBN} circumvents the error by ignoring this symbol information. |
8362 | This usually allows you to debug your program, though certain symbols | |
c906108c | 8363 | are not accessible. If you encounter such a problem and feel like |
7a292a7a SS |
8364 | debugging it, you can debug @code{@value{GDBP}} with itself, breakpoint |
8365 | on @code{complain}, then go up to the function @code{read_dbx_symtab} | |
8366 | and examine @code{*bufp} to see the symbol. | |
c906108c SS |
8367 | |
8368 | @item stub type has NULL name | |
c906108c | 8369 | |
7a292a7a | 8370 | @value{GDBN} could not find the full definition for a struct or class. |
c906108c | 8371 | |
7a292a7a | 8372 | @item const/volatile indicator missing (ok if using g++ v1.x), got@dots{} |
c906108c | 8373 | The symbol information for a C++ member function is missing some |
7a292a7a SS |
8374 | information that recent versions of the compiler should have output for |
8375 | it. | |
c906108c SS |
8376 | |
8377 | @item info mismatch between compiler and debugger | |
8378 | ||
8379 | @value{GDBN} could not parse a type specification output by the compiler. | |
7a292a7a | 8380 | |
c906108c SS |
8381 | @end table |
8382 | ||
6d2ebf8b | 8383 | @node Targets |
c906108c | 8384 | @chapter Specifying a Debugging Target |
7a292a7a | 8385 | |
c906108c SS |
8386 | @cindex debugging target |
8387 | @kindex target | |
8388 | ||
8389 | A @dfn{target} is the execution environment occupied by your program. | |
53a5351d JM |
8390 | |
8391 | Often, @value{GDBN} runs in the same host environment as your program; | |
8392 | in that case, the debugging target is specified as a side effect when | |
8393 | you use the @code{file} or @code{core} commands. When you need more | |
c906108c SS |
8394 | flexibility---for example, running @value{GDBN} on a physically separate |
8395 | host, or controlling a standalone system over a serial port or a | |
53a5351d JM |
8396 | realtime system over a TCP/IP connection---you can use the @code{target} |
8397 | command to specify one of the target types configured for @value{GDBN} | |
8398 | (@pxref{Target Commands, ,Commands for managing targets}). | |
c906108c SS |
8399 | |
8400 | @menu | |
8401 | * Active Targets:: Active targets | |
8402 | * Target Commands:: Commands for managing targets | |
c906108c SS |
8403 | * Byte Order:: Choosing target byte order |
8404 | * Remote:: Remote debugging | |
96baa820 | 8405 | * KOD:: Kernel Object Display |
c906108c SS |
8406 | |
8407 | @end menu | |
8408 | ||
6d2ebf8b | 8409 | @node Active Targets |
c906108c | 8410 | @section Active targets |
7a292a7a | 8411 | |
c906108c SS |
8412 | @cindex stacking targets |
8413 | @cindex active targets | |
8414 | @cindex multiple targets | |
8415 | ||
c906108c | 8416 | There are three classes of targets: processes, core files, and |
7a292a7a SS |
8417 | executable files. @value{GDBN} can work concurrently on up to three |
8418 | active targets, one in each class. This allows you to (for example) | |
8419 | start a process and inspect its activity without abandoning your work on | |
8420 | a core file. | |
c906108c SS |
8421 | |
8422 | For example, if you execute @samp{gdb a.out}, then the executable file | |
8423 | @code{a.out} is the only active target. If you designate a core file as | |
8424 | well---presumably from a prior run that crashed and coredumped---then | |
8425 | @value{GDBN} has two active targets and uses them in tandem, looking | |
8426 | first in the corefile target, then in the executable file, to satisfy | |
8427 | requests for memory addresses. (Typically, these two classes of target | |
8428 | are complementary, since core files contain only a program's | |
8429 | read-write memory---variables and so on---plus machine status, while | |
8430 | executable files contain only the program text and initialized data.) | |
c906108c SS |
8431 | |
8432 | When you type @code{run}, your executable file becomes an active process | |
7a292a7a SS |
8433 | target as well. When a process target is active, all @value{GDBN} |
8434 | commands requesting memory addresses refer to that target; addresses in | |
8435 | an active core file or executable file target are obscured while the | |
8436 | process target is active. | |
c906108c | 8437 | |
7a292a7a SS |
8438 | Use the @code{core-file} and @code{exec-file} commands to select a new |
8439 | core file or executable target (@pxref{Files, ,Commands to specify | |
c906108c | 8440 | files}). To specify as a target a process that is already running, use |
7a292a7a SS |
8441 | the @code{attach} command (@pxref{Attach, ,Debugging an already-running |
8442 | process}). | |
c906108c | 8443 | |
6d2ebf8b | 8444 | @node Target Commands |
c906108c SS |
8445 | @section Commands for managing targets |
8446 | ||
8447 | @table @code | |
8448 | @item target @var{type} @var{parameters} | |
7a292a7a SS |
8449 | Connects the @value{GDBN} host environment to a target machine or |
8450 | process. A target is typically a protocol for talking to debugging | |
8451 | facilities. You use the argument @var{type} to specify the type or | |
8452 | protocol of the target machine. | |
c906108c SS |
8453 | |
8454 | Further @var{parameters} are interpreted by the target protocol, but | |
8455 | typically include things like device names or host names to connect | |
8456 | with, process numbers, and baud rates. | |
c906108c SS |
8457 | |
8458 | The @code{target} command does not repeat if you press @key{RET} again | |
8459 | after executing the command. | |
8460 | ||
8461 | @kindex help target | |
8462 | @item help target | |
8463 | Displays the names of all targets available. To display targets | |
8464 | currently selected, use either @code{info target} or @code{info files} | |
8465 | (@pxref{Files, ,Commands to specify files}). | |
8466 | ||
8467 | @item help target @var{name} | |
8468 | Describe a particular target, including any parameters necessary to | |
8469 | select it. | |
8470 | ||
8471 | @kindex set gnutarget | |
8472 | @item set gnutarget @var{args} | |
5d161b24 | 8473 | @value{GDBN} uses its own library BFD to read your files. @value{GDBN} |
c906108c | 8474 | knows whether it is reading an @dfn{executable}, |
5d161b24 DB |
8475 | a @dfn{core}, or a @dfn{.o} file; however, you can specify the file format |
8476 | with the @code{set gnutarget} command. Unlike most @code{target} commands, | |
c906108c SS |
8477 | with @code{gnutarget} the @code{target} refers to a program, not a machine. |
8478 | ||
d4f3574e | 8479 | @quotation |
c906108c SS |
8480 | @emph{Warning:} To specify a file format with @code{set gnutarget}, |
8481 | you must know the actual BFD name. | |
d4f3574e | 8482 | @end quotation |
c906108c | 8483 | |
d4f3574e SS |
8484 | @noindent |
8485 | @xref{Files, , Commands to specify files}. | |
c906108c | 8486 | |
5d161b24 | 8487 | @kindex show gnutarget |
c906108c SS |
8488 | @item show gnutarget |
8489 | Use the @code{show gnutarget} command to display what file format | |
8490 | @code{gnutarget} is set to read. If you have not set @code{gnutarget}, | |
8491 | @value{GDBN} will determine the file format for each file automatically, | |
8492 | and @code{show gnutarget} displays @samp{The current BDF target is "auto"}. | |
8493 | @end table | |
8494 | ||
c906108c SS |
8495 | Here are some common targets (available, or not, depending on the GDB |
8496 | configuration): | |
c906108c SS |
8497 | |
8498 | @table @code | |
8499 | @kindex target exec | |
8500 | @item target exec @var{program} | |
8501 | An executable file. @samp{target exec @var{program}} is the same as | |
8502 | @samp{exec-file @var{program}}. | |
8503 | ||
c906108c SS |
8504 | @kindex target core |
8505 | @item target core @var{filename} | |
8506 | A core dump file. @samp{target core @var{filename}} is the same as | |
8507 | @samp{core-file @var{filename}}. | |
c906108c SS |
8508 | |
8509 | @kindex target remote | |
8510 | @item target remote @var{dev} | |
8511 | Remote serial target in GDB-specific protocol. The argument @var{dev} | |
8512 | specifies what serial device to use for the connection (e.g. | |
8513 | @file{/dev/ttya}). @xref{Remote, ,Remote debugging}. @code{target remote} | |
d4f3574e | 8514 | supports the @code{load} command. This is only useful if you have |
c906108c SS |
8515 | some other way of getting the stub to the target system, and you can put |
8516 | it somewhere in memory where it won't get clobbered by the download. | |
8517 | ||
c906108c SS |
8518 | @kindex target sim |
8519 | @item target sim | |
2df3850c | 8520 | Builtin CPU simulator. @value{GDBN} includes simulators for most architectures. |
104c1213 JM |
8521 | In general, |
8522 | @example | |
8523 | target sim | |
8524 | load | |
8525 | run | |
8526 | @end example | |
d4f3574e | 8527 | @noindent |
104c1213 | 8528 | works; however, you cannot assume that a specific memory map, device |
d4f3574e | 8529 | drivers, or even basic I/O is available, although some simulators do |
104c1213 JM |
8530 | provide these. For info about any processor-specific simulator details, |
8531 | see the appropriate section in @ref{Embedded Processors, ,Embedded | |
8532 | Processors}. | |
8533 | ||
c906108c SS |
8534 | @end table |
8535 | ||
104c1213 | 8536 | Some configurations may include these targets as well: |
c906108c SS |
8537 | |
8538 | @table @code | |
8539 | ||
c906108c SS |
8540 | @kindex target nrom |
8541 | @item target nrom @var{dev} | |
8542 | NetROM ROM emulator. This target only supports downloading. | |
8543 | ||
c906108c SS |
8544 | @end table |
8545 | ||
5d161b24 | 8546 | Different targets are available on different configurations of @value{GDBN}; |
c906108c | 8547 | your configuration may have more or fewer targets. |
c906108c SS |
8548 | |
8549 | Many remote targets require you to download the executable's code | |
8550 | once you've successfully established a connection. | |
8551 | ||
8552 | @table @code | |
8553 | ||
8554 | @kindex load @var{filename} | |
8555 | @item load @var{filename} | |
c906108c SS |
8556 | Depending on what remote debugging facilities are configured into |
8557 | @value{GDBN}, the @code{load} command may be available. Where it exists, it | |
8558 | is meant to make @var{filename} (an executable) available for debugging | |
8559 | on the remote system---by downloading, or dynamic linking, for example. | |
8560 | @code{load} also records the @var{filename} symbol table in @value{GDBN}, like | |
8561 | the @code{add-symbol-file} command. | |
8562 | ||
8563 | If your @value{GDBN} does not have a @code{load} command, attempting to | |
8564 | execute it gets the error message ``@code{You can't do that when your | |
8565 | target is @dots{}}'' | |
c906108c SS |
8566 | |
8567 | The file is loaded at whatever address is specified in the executable. | |
8568 | For some object file formats, you can specify the load address when you | |
8569 | link the program; for other formats, like a.out, the object file format | |
8570 | specifies a fixed address. | |
8571 | @c FIXME! This would be a good place for an xref to the GNU linker doc. | |
8572 | ||
c906108c SS |
8573 | @code{load} does not repeat if you press @key{RET} again after using it. |
8574 | @end table | |
8575 | ||
6d2ebf8b | 8576 | @node Byte Order |
c906108c | 8577 | @section Choosing target byte order |
7a292a7a | 8578 | |
c906108c SS |
8579 | @cindex choosing target byte order |
8580 | @cindex target byte order | |
c906108c SS |
8581 | |
8582 | Some types of processors, such as the MIPS, PowerPC, and Hitachi SH, | |
8583 | offer the ability to run either big-endian or little-endian byte | |
8584 | orders. Usually the executable or symbol will include a bit to | |
8585 | designate the endian-ness, and you will not need to worry about | |
8586 | which to use. However, you may still find it useful to adjust | |
d4f3574e | 8587 | @value{GDBN}'s idea of processor endian-ness manually. |
c906108c SS |
8588 | |
8589 | @table @code | |
8590 | @kindex set endian big | |
8591 | @item set endian big | |
8592 | Instruct @value{GDBN} to assume the target is big-endian. | |
8593 | ||
8594 | @kindex set endian little | |
8595 | @item set endian little | |
8596 | Instruct @value{GDBN} to assume the target is little-endian. | |
8597 | ||
8598 | @kindex set endian auto | |
8599 | @item set endian auto | |
8600 | Instruct @value{GDBN} to use the byte order associated with the | |
8601 | executable. | |
8602 | ||
8603 | @item show endian | |
8604 | Display @value{GDBN}'s current idea of the target byte order. | |
8605 | ||
8606 | @end table | |
8607 | ||
8608 | Note that these commands merely adjust interpretation of symbolic | |
8609 | data on the host, and that they have absolutely no effect on the | |
8610 | target system. | |
8611 | ||
6d2ebf8b | 8612 | @node Remote |
c906108c SS |
8613 | @section Remote debugging |
8614 | @cindex remote debugging | |
8615 | ||
8616 | If you are trying to debug a program running on a machine that cannot run | |
5d161b24 DB |
8617 | @value{GDBN} in the usual way, it is often useful to use remote debugging. |
8618 | For example, you might use remote debugging on an operating system kernel, | |
c906108c SS |
8619 | or on a small system which does not have a general purpose operating system |
8620 | powerful enough to run a full-featured debugger. | |
8621 | ||
8622 | Some configurations of @value{GDBN} have special serial or TCP/IP interfaces | |
8623 | to make this work with particular debugging targets. In addition, | |
5d161b24 | 8624 | @value{GDBN} comes with a generic serial protocol (specific to @value{GDBN}, |
c906108c SS |
8625 | but not specific to any particular target system) which you can use if you |
8626 | write the remote stubs---the code that runs on the remote system to | |
8627 | communicate with @value{GDBN}. | |
8628 | ||
8629 | Other remote targets may be available in your | |
8630 | configuration of @value{GDBN}; use @code{help target} to list them. | |
c906108c | 8631 | |
c906108c | 8632 | @menu |
c906108c | 8633 | * Remote Serial:: @value{GDBN} remote serial protocol |
c906108c SS |
8634 | @end menu |
8635 | ||
6d2ebf8b | 8636 | @node Remote Serial |
104c1213 | 8637 | @subsection The @value{GDBN} remote serial protocol |
7a292a7a | 8638 | |
104c1213 JM |
8639 | @cindex remote serial debugging, overview |
8640 | To debug a program running on another machine (the debugging | |
8641 | @dfn{target} machine), you must first arrange for all the usual | |
8642 | prerequisites for the program to run by itself. For example, for a C | |
8643 | program, you need: | |
c906108c | 8644 | |
104c1213 JM |
8645 | @enumerate |
8646 | @item | |
8647 | A startup routine to set up the C runtime environment; these usually | |
8648 | have a name like @file{crt0}. The startup routine may be supplied by | |
8649 | your hardware supplier, or you may have to write your own. | |
96baa820 | 8650 | |
5d161b24 | 8651 | @item |
d4f3574e | 8652 | A C subroutine library to support your program's |
104c1213 | 8653 | subroutine calls, notably managing input and output. |
96baa820 | 8654 | |
104c1213 JM |
8655 | @item |
8656 | A way of getting your program to the other machine---for example, a | |
8657 | download program. These are often supplied by the hardware | |
8658 | manufacturer, but you may have to write your own from hardware | |
8659 | documentation. | |
8660 | @end enumerate | |
96baa820 | 8661 | |
104c1213 JM |
8662 | The next step is to arrange for your program to use a serial port to |
8663 | communicate with the machine where @value{GDBN} is running (the @dfn{host} | |
8664 | machine). In general terms, the scheme looks like this: | |
96baa820 | 8665 | |
104c1213 JM |
8666 | @table @emph |
8667 | @item On the host, | |
8668 | @value{GDBN} already understands how to use this protocol; when everything | |
8669 | else is set up, you can simply use the @samp{target remote} command | |
8670 | (@pxref{Targets,,Specifying a Debugging Target}). | |
8671 | ||
8672 | @item On the target, | |
8673 | you must link with your program a few special-purpose subroutines that | |
8674 | implement the @value{GDBN} remote serial protocol. The file containing these | |
8675 | subroutines is called a @dfn{debugging stub}. | |
8676 | ||
8677 | On certain remote targets, you can use an auxiliary program | |
8678 | @code{gdbserver} instead of linking a stub into your program. | |
8679 | @xref{Server,,Using the @code{gdbserver} program}, for details. | |
8680 | @end table | |
96baa820 | 8681 | |
104c1213 JM |
8682 | The debugging stub is specific to the architecture of the remote |
8683 | machine; for example, use @file{sparc-stub.c} to debug programs on | |
8684 | @sc{sparc} boards. | |
96baa820 | 8685 | |
104c1213 JM |
8686 | @cindex remote serial stub list |
8687 | These working remote stubs are distributed with @value{GDBN}: | |
96baa820 | 8688 | |
104c1213 JM |
8689 | @table @code |
8690 | ||
8691 | @item i386-stub.c | |
41afff9a | 8692 | @cindex @file{i386-stub.c} |
104c1213 JM |
8693 | @cindex Intel |
8694 | @cindex i386 | |
8695 | For Intel 386 and compatible architectures. | |
8696 | ||
8697 | @item m68k-stub.c | |
41afff9a | 8698 | @cindex @file{m68k-stub.c} |
104c1213 JM |
8699 | @cindex Motorola 680x0 |
8700 | @cindex m680x0 | |
8701 | For Motorola 680x0 architectures. | |
8702 | ||
8703 | @item sh-stub.c | |
41afff9a | 8704 | @cindex @file{sh-stub.c} |
104c1213 JM |
8705 | @cindex Hitachi |
8706 | @cindex SH | |
8707 | For Hitachi SH architectures. | |
8708 | ||
8709 | @item sparc-stub.c | |
41afff9a | 8710 | @cindex @file{sparc-stub.c} |
104c1213 JM |
8711 | @cindex Sparc |
8712 | For @sc{sparc} architectures. | |
8713 | ||
8714 | @item sparcl-stub.c | |
41afff9a | 8715 | @cindex @file{sparcl-stub.c} |
104c1213 JM |
8716 | @cindex Fujitsu |
8717 | @cindex SparcLite | |
8718 | For Fujitsu @sc{sparclite} architectures. | |
8719 | ||
8720 | @end table | |
8721 | ||
8722 | The @file{README} file in the @value{GDBN} distribution may list other | |
8723 | recently added stubs. | |
8724 | ||
8725 | @menu | |
8726 | * Stub Contents:: What the stub can do for you | |
8727 | * Bootstrapping:: What you must do for the stub | |
8728 | * Debug Session:: Putting it all together | |
8729 | * Protocol:: Definition of the communication protocol | |
8730 | * Server:: Using the `gdbserver' program | |
8731 | * NetWare:: Using the `gdbserve.nlm' program | |
8732 | @end menu | |
8733 | ||
6d2ebf8b | 8734 | @node Stub Contents |
104c1213 JM |
8735 | @subsubsection What the stub can do for you |
8736 | ||
8737 | @cindex remote serial stub | |
8738 | The debugging stub for your architecture supplies these three | |
8739 | subroutines: | |
8740 | ||
8741 | @table @code | |
8742 | @item set_debug_traps | |
8743 | @kindex set_debug_traps | |
8744 | @cindex remote serial stub, initialization | |
8745 | This routine arranges for @code{handle_exception} to run when your | |
8746 | program stops. You must call this subroutine explicitly near the | |
8747 | beginning of your program. | |
8748 | ||
8749 | @item handle_exception | |
8750 | @kindex handle_exception | |
8751 | @cindex remote serial stub, main routine | |
8752 | This is the central workhorse, but your program never calls it | |
8753 | explicitly---the setup code arranges for @code{handle_exception} to | |
8754 | run when a trap is triggered. | |
8755 | ||
8756 | @code{handle_exception} takes control when your program stops during | |
8757 | execution (for example, on a breakpoint), and mediates communications | |
8758 | with @value{GDBN} on the host machine. This is where the communications | |
8759 | protocol is implemented; @code{handle_exception} acts as the @value{GDBN} | |
d4f3574e | 8760 | representative on the target machine. It begins by sending summary |
104c1213 JM |
8761 | information on the state of your program, then continues to execute, |
8762 | retrieving and transmitting any information @value{GDBN} needs, until you | |
8763 | execute a @value{GDBN} command that makes your program resume; at that point, | |
8764 | @code{handle_exception} returns control to your own code on the target | |
5d161b24 | 8765 | machine. |
104c1213 JM |
8766 | |
8767 | @item breakpoint | |
8768 | @cindex @code{breakpoint} subroutine, remote | |
8769 | Use this auxiliary subroutine to make your program contain a | |
8770 | breakpoint. Depending on the particular situation, this may be the only | |
8771 | way for @value{GDBN} to get control. For instance, if your target | |
8772 | machine has some sort of interrupt button, you won't need to call this; | |
8773 | pressing the interrupt button transfers control to | |
8774 | @code{handle_exception}---in effect, to @value{GDBN}. On some machines, | |
8775 | simply receiving characters on the serial port may also trigger a trap; | |
8776 | again, in that situation, you don't need to call @code{breakpoint} from | |
8777 | your own program---simply running @samp{target remote} from the host | |
5d161b24 | 8778 | @value{GDBN} session gets control. |
104c1213 JM |
8779 | |
8780 | Call @code{breakpoint} if none of these is true, or if you simply want | |
8781 | to make certain your program stops at a predetermined point for the | |
8782 | start of your debugging session. | |
8783 | @end table | |
8784 | ||
6d2ebf8b | 8785 | @node Bootstrapping |
104c1213 JM |
8786 | @subsubsection What you must do for the stub |
8787 | ||
8788 | @cindex remote stub, support routines | |
8789 | The debugging stubs that come with @value{GDBN} are set up for a particular | |
8790 | chip architecture, but they have no information about the rest of your | |
8791 | debugging target machine. | |
8792 | ||
8793 | First of all you need to tell the stub how to communicate with the | |
8794 | serial port. | |
8795 | ||
8796 | @table @code | |
8797 | @item int getDebugChar() | |
8798 | @kindex getDebugChar | |
8799 | Write this subroutine to read a single character from the serial port. | |
8800 | It may be identical to @code{getchar} for your target system; a | |
8801 | different name is used to allow you to distinguish the two if you wish. | |
8802 | ||
8803 | @item void putDebugChar(int) | |
8804 | @kindex putDebugChar | |
8805 | Write this subroutine to write a single character to the serial port. | |
5d161b24 | 8806 | It may be identical to @code{putchar} for your target system; a |
104c1213 JM |
8807 | different name is used to allow you to distinguish the two if you wish. |
8808 | @end table | |
8809 | ||
8810 | @cindex control C, and remote debugging | |
8811 | @cindex interrupting remote targets | |
8812 | If you want @value{GDBN} to be able to stop your program while it is | |
8813 | running, you need to use an interrupt-driven serial driver, and arrange | |
8814 | for it to stop when it receives a @code{^C} (@samp{\003}, the control-C | |
8815 | character). That is the character which @value{GDBN} uses to tell the | |
8816 | remote system to stop. | |
8817 | ||
8818 | Getting the debugging target to return the proper status to @value{GDBN} | |
8819 | probably requires changes to the standard stub; one quick and dirty way | |
8820 | is to just execute a breakpoint instruction (the ``dirty'' part is that | |
8821 | @value{GDBN} reports a @code{SIGTRAP} instead of a @code{SIGINT}). | |
8822 | ||
8823 | Other routines you need to supply are: | |
8824 | ||
8825 | @table @code | |
8826 | @item void exceptionHandler (int @var{exception_number}, void *@var{exception_address}) | |
8827 | @kindex exceptionHandler | |
8828 | Write this function to install @var{exception_address} in the exception | |
8829 | handling tables. You need to do this because the stub does not have any | |
8830 | way of knowing what the exception handling tables on your target system | |
8831 | are like (for example, the processor's table might be in @sc{rom}, | |
8832 | containing entries which point to a table in @sc{ram}). | |
8833 | @var{exception_number} is the exception number which should be changed; | |
8834 | its meaning is architecture-dependent (for example, different numbers | |
8835 | might represent divide by zero, misaligned access, etc). When this | |
8836 | exception occurs, control should be transferred directly to | |
8837 | @var{exception_address}, and the processor state (stack, registers, | |
8838 | and so on) should be just as it is when a processor exception occurs. So if | |
8839 | you want to use a jump instruction to reach @var{exception_address}, it | |
8840 | should be a simple jump, not a jump to subroutine. | |
8841 | ||
8842 | For the 386, @var{exception_address} should be installed as an interrupt | |
8843 | gate so that interrupts are masked while the handler runs. The gate | |
8844 | should be at privilege level 0 (the most privileged level). The | |
8845 | @sc{sparc} and 68k stubs are able to mask interrupts themselves without | |
8846 | help from @code{exceptionHandler}. | |
8847 | ||
8848 | @item void flush_i_cache() | |
8849 | @kindex flush_i_cache | |
d4f3574e | 8850 | On @sc{sparc} and @sc{sparclite} only, write this subroutine to flush the |
104c1213 JM |
8851 | instruction cache, if any, on your target machine. If there is no |
8852 | instruction cache, this subroutine may be a no-op. | |
8853 | ||
8854 | On target machines that have instruction caches, @value{GDBN} requires this | |
8855 | function to make certain that the state of your program is stable. | |
8856 | @end table | |
8857 | ||
8858 | @noindent | |
8859 | You must also make sure this library routine is available: | |
8860 | ||
8861 | @table @code | |
8862 | @item void *memset(void *, int, int) | |
8863 | @kindex memset | |
8864 | This is the standard library function @code{memset} that sets an area of | |
8865 | memory to a known value. If you have one of the free versions of | |
8866 | @code{libc.a}, @code{memset} can be found there; otherwise, you must | |
8867 | either obtain it from your hardware manufacturer, or write your own. | |
8868 | @end table | |
8869 | ||
8870 | If you do not use the GNU C compiler, you may need other standard | |
8871 | library subroutines as well; this varies from one stub to another, | |
8872 | but in general the stubs are likely to use any of the common library | |
d4f3574e | 8873 | subroutines which @code{@value{GCC}} generates as inline code. |
104c1213 JM |
8874 | |
8875 | ||
6d2ebf8b | 8876 | @node Debug Session |
104c1213 JM |
8877 | @subsubsection Putting it all together |
8878 | ||
8879 | @cindex remote serial debugging summary | |
8880 | In summary, when your program is ready to debug, you must follow these | |
8881 | steps. | |
8882 | ||
8883 | @enumerate | |
8884 | @item | |
6d2ebf8b | 8885 | Make sure you have defined the supporting low-level routines |
104c1213 JM |
8886 | (@pxref{Bootstrapping,,What you must do for the stub}): |
8887 | @display | |
8888 | @code{getDebugChar}, @code{putDebugChar}, | |
8889 | @code{flush_i_cache}, @code{memset}, @code{exceptionHandler}. | |
8890 | @end display | |
8891 | ||
8892 | @item | |
8893 | Insert these lines near the top of your program: | |
8894 | ||
8895 | @example | |
8896 | set_debug_traps(); | |
8897 | breakpoint(); | |
8898 | @end example | |
8899 | ||
8900 | @item | |
8901 | For the 680x0 stub only, you need to provide a variable called | |
8902 | @code{exceptionHook}. Normally you just use: | |
8903 | ||
8904 | @example | |
8905 | void (*exceptionHook)() = 0; | |
8906 | @end example | |
8907 | ||
d4f3574e | 8908 | @noindent |
104c1213 | 8909 | but if before calling @code{set_debug_traps}, you set it to point to a |
598ca718 | 8910 | function in your program, that function is called when |
104c1213 JM |
8911 | @code{@value{GDBN}} continues after stopping on a trap (for example, bus |
8912 | error). The function indicated by @code{exceptionHook} is called with | |
8913 | one parameter: an @code{int} which is the exception number. | |
8914 | ||
8915 | @item | |
8916 | Compile and link together: your program, the @value{GDBN} debugging stub for | |
8917 | your target architecture, and the supporting subroutines. | |
8918 | ||
8919 | @item | |
8920 | Make sure you have a serial connection between your target machine and | |
8921 | the @value{GDBN} host, and identify the serial port on the host. | |
8922 | ||
8923 | @item | |
8924 | @c The "remote" target now provides a `load' command, so we should | |
8925 | @c document that. FIXME. | |
8926 | Download your program to your target machine (or get it there by | |
8927 | whatever means the manufacturer provides), and start it. | |
8928 | ||
8929 | @item | |
8930 | To start remote debugging, run @value{GDBN} on the host machine, and specify | |
8931 | as an executable file the program that is running in the remote machine. | |
8932 | This tells @value{GDBN} how to find your program's symbols and the contents | |
8933 | of its pure text. | |
8934 | ||
d4f3574e | 8935 | @item |
104c1213 | 8936 | @cindex serial line, @code{target remote} |
d4f3574e | 8937 | Establish communication using the @code{target remote} command. |
104c1213 JM |
8938 | Its argument specifies how to communicate with the target |
8939 | machine---either via a devicename attached to a direct serial line, or a | |
8940 | TCP port (usually to a terminal server which in turn has a serial line | |
8941 | to the target). For example, to use a serial line connected to the | |
8942 | device named @file{/dev/ttyb}: | |
8943 | ||
8944 | @example | |
8945 | target remote /dev/ttyb | |
8946 | @end example | |
8947 | ||
8948 | @cindex TCP port, @code{target remote} | |
8949 | To use a TCP connection, use an argument of the form | |
8950 | @code{@var{host}:port}. For example, to connect to port 2828 on a | |
8951 | terminal server named @code{manyfarms}: | |
8952 | ||
8953 | @example | |
8954 | target remote manyfarms:2828 | |
8955 | @end example | |
8956 | @end enumerate | |
8957 | ||
8958 | Now you can use all the usual commands to examine and change data and to | |
8959 | step and continue the remote program. | |
8960 | ||
8961 | To resume the remote program and stop debugging it, use the @code{detach} | |
8962 | command. | |
8963 | ||
8964 | @cindex interrupting remote programs | |
8965 | @cindex remote programs, interrupting | |
8966 | Whenever @value{GDBN} is waiting for the remote program, if you type the | |
8967 | interrupt character (often @key{C-C}), @value{GDBN} attempts to stop the | |
8968 | program. This may or may not succeed, depending in part on the hardware | |
8969 | and the serial drivers the remote system uses. If you type the | |
8970 | interrupt character once again, @value{GDBN} displays this prompt: | |
8971 | ||
8972 | @example | |
8973 | Interrupted while waiting for the program. | |
8974 | Give up (and stop debugging it)? (y or n) | |
8975 | @end example | |
8976 | ||
8977 | If you type @kbd{y}, @value{GDBN} abandons the remote debugging session. | |
8978 | (If you decide you want to try again later, you can use @samp{target | |
8979 | remote} again to connect once more.) If you type @kbd{n}, @value{GDBN} | |
8980 | goes back to waiting. | |
8981 | ||
6d2ebf8b | 8982 | @node Protocol |
104c1213 JM |
8983 | @subsubsection Communication protocol |
8984 | ||
8985 | @cindex debugging stub, example | |
8986 | @cindex remote stub, example | |
8987 | @cindex stub example, remote debugging | |
8988 | The stub files provided with @value{GDBN} implement the target side of the | |
8989 | communication protocol, and the @value{GDBN} side is implemented in the | |
8990 | @value{GDBN} source file @file{remote.c}. Normally, you can simply allow | |
8991 | these subroutines to communicate, and ignore the details. (If you're | |
8992 | implementing your own stub file, you can still ignore the details: start | |
8993 | with one of the existing stub files. @file{sparc-stub.c} is the best | |
8994 | organized, and therefore the easiest to read.) | |
8995 | ||
8996 | However, there may be occasions when you need to know something about | |
8997 | the protocol---for example, if there is only one serial port to your | |
8998 | target machine, you might want your program to do something special if | |
8999 | it recognizes a packet meant for @value{GDBN}. | |
9000 | ||
9001 | In the examples below, @samp{<-} and @samp{->} are used to indicate | |
9002 | transmitted and received data respectfully. | |
9003 | ||
9004 | @cindex protocol, @value{GDBN} remote serial | |
9005 | @cindex serial protocol, @value{GDBN} remote | |
9006 | @cindex remote serial protocol | |
6cf7e474 AC |
9007 | All @value{GDBN} commands and responses (other than acknowledgments) are |
9008 | sent as a @var{packet}. A @var{packet} is introduced with the character | |
9009 | @samp{$}, the actual @var{packet-data}, and the terminating character | |
9010 | @samp{#} followed by a two-digit @var{checksum}: | |
104c1213 JM |
9011 | |
9012 | @example | |
9013 | @code{$}@var{packet-data}@code{#}@var{checksum} | |
9014 | @end example | |
9015 | @noindent | |
104c1213 JM |
9016 | |
9017 | @cindex checksum, for @value{GDBN} remote | |
9018 | @noindent | |
9019 | The two-digit @var{checksum} is computed as the modulo 256 sum of all | |
6cf7e474 AC |
9020 | characters between the leading @samp{$} and the trailing @samp{#} (an |
9021 | eight bit unsigned checksum). | |
9022 | ||
9023 | Implementors should note that prior to @value{GDBN} 5.0 the protocol | |
9024 | specification also included an optional two-digit @var{sequence-id}: | |
9025 | ||
9026 | @example | |
9027 | @code{$}@var{sequence-id}@code{:}@var{packet-data}@code{#}@var{checksum} | |
9028 | @end example | |
104c1213 JM |
9029 | |
9030 | @cindex sequence-id, for @value{GDBN} remote | |
9031 | @noindent | |
6cf7e474 AC |
9032 | That @var{sequence-id} was appended to the acknowledgment. @value{GDBN} |
9033 | has never output @var{sequence-id}s. Stubs that handle packets added | |
9034 | since @value{GDBN} 5.0 must not accept @var{sequence-id}. | |
104c1213 | 9035 | |
6cf7e474 | 9036 | @cindex acknowledgment, for @value{GDBN} remote |
104c1213 JM |
9037 | When either the host or the target machine receives a packet, the first |
9038 | response expected is an acknowledgment: either @samp{+} (to indicate | |
9039 | the package was received correctly) or @samp{-} (to request | |
9040 | retransmission): | |
9041 | ||
9042 | @example | |
9043 | <- @code{$}@var{packet-data}@code{#}@var{checksum} | |
9044 | -> @code{+} | |
9045 | @end example | |
9046 | @noindent | |
104c1213 JM |
9047 | |
9048 | The host (@value{GDBN}) sends @var{command}s, and the target (the | |
9049 | debugging stub incorporated in your program) sends a @var{response}. In | |
9050 | the case of step and continue @var{command}s, the response is only sent | |
9051 | when the operation has completed (the target has again stopped). | |
9052 | ||
9053 | @var{packet-data} consists of a sequence of characters with the | |
6cf7e474 AC |
9054 | exception of @samp{#} and @samp{$} (see @samp{X} packet for additional |
9055 | exceptions). | |
9056 | ||
9057 | Fields within the packet should be separated using @samp{,} @samp{;} or | |
9058 | @samp{:}. Except where otherwise noted all numbers are represented in | |
9059 | HEX with leading zeros suppressed. | |
9060 | ||
9061 | Implementors should note that prior to @value{GDBN} 5.0, the character | |
9062 | @samp{:} could not appear as the third character in a packet (as it | |
9063 | would potentially conflict with the @var{sequence-id}). | |
104c1213 JM |
9064 | |
9065 | Response @var{data} can be run-length encoded to save space. A @samp{*} | |
c3f6f71d | 9066 | means that the next character is an @sc{ascii} encoding giving a repeat count |
104c1213 JM |
9067 | which stands for that many repetitions of the character preceding the |
9068 | @samp{*}. The encoding is @code{n+29}, yielding a printable character | |
d4f3574e SS |
9069 | where @code{n >=3} (which is where rle starts to win). The printable |
9070 | characters @samp{$}, @samp{#}, @samp{+} and @samp{-} or with a numeric | |
9071 | value greater than 126 should not be used. | |
9072 | ||
9073 | Some remote systems have used a different run-length encoding mechanism | |
9074 | loosely refered to as the cisco encoding. Following the @samp{*} | |
9075 | character are two hex digits that indicate the size of the packet. | |
104c1213 JM |
9076 | |
9077 | So: | |
9078 | @example | |
9079 | "@code{0* }" | |
9080 | @end example | |
9081 | @noindent | |
9082 | means the same as "0000". | |
9083 | ||
598ca718 | 9084 | The error response returned for some packets includes a two character |
104c1213 JM |
9085 | error number. That number is not well defined. |
9086 | ||
9087 | For any @var{command} not supported by the stub, an empty response | |
9088 | (@samp{$#00}) should be returned. That way it is possible to extend the | |
9089 | protocol. A newer @value{GDBN} can tell if a packet is supported based | |
d4f3574e | 9090 | on that response. |
104c1213 | 9091 | |
f1251bdd C |
9092 | A stub is required to support the @samp{g}, @samp{G}, @samp{m}, @samp{M}, |
9093 | @samp{c}, and @samp{s} @var{command}s. All other @var{command}s are | |
9094 | optional. | |
9095 | ||
104c1213 JM |
9096 | Below is a complete list of all currently defined @var{command}s and |
9097 | their corresponding response @var{data}: | |
598ca718 | 9098 | @page |
104c1213 JM |
9099 | @multitable @columnfractions .30 .30 .40 |
9100 | @item Packet | |
9101 | @tab Request | |
9102 | @tab Description | |
9103 | ||
f1251bdd | 9104 | @item extended ops |
104c1213 JM |
9105 | @tab @code{!} |
9106 | @tab | |
d4f3574e | 9107 | Use the extended remote protocol. Sticky---only needs to be set once. |
598ca718 | 9108 | The extended remote protocol supports the @samp{R} packet. |
104c1213 JM |
9109 | @item |
9110 | @tab reply @samp{} | |
9111 | @tab | |
9112 | Stubs that support the extended remote protocol return @samp{} which, | |
9113 | unfortunately, is identical to the response returned by stubs that do not | |
9114 | support protocol extensions. | |
9115 | ||
9116 | @item last signal | |
9117 | @tab @code{?} | |
9118 | @tab | |
d4f3574e SS |
9119 | Indicate the reason the target halted. The reply is the same as for step |
9120 | and continue. | |
9121 | @item | |
9122 | @tab reply | |
9123 | @tab see below | |
9124 | ||
104c1213 JM |
9125 | |
9126 | @item reserved | |
9127 | @tab @code{a} | |
5d161b24 | 9128 | @tab Reserved for future use |
104c1213 | 9129 | |
f1251bdd | 9130 | @item set program arguments @strong{(reserved)} |
104c1213 JM |
9131 | @tab @code{A}@var{arglen}@code{,}@var{argnum}@code{,}@var{arg}@code{,...} |
9132 | @tab | |
598ca718 EZ |
9133 | @item |
9134 | @tab | |
9135 | @tab | |
104c1213 JM |
9136 | Initialized @samp{argv[]} array passed into program. @var{arglen} |
9137 | specifies the number of bytes in the hex encoded byte stream @var{arg}. | |
d4f3574e | 9138 | See @file{gdbserver} for more details. |
104c1213 JM |
9139 | @item |
9140 | @tab reply @code{OK} | |
9141 | @item | |
9142 | @tab reply @code{E}@var{NN} | |
9143 | ||
9144 | @item set baud @strong{(deprecated)} | |
9145 | @tab @code{b}@var{baud} | |
9146 | @tab | |
9147 | Change the serial line speed to @var{baud}. JTC: @emph{When does the | |
9148 | transport layer state change? When it's received, or after the ACK is | |
9149 | transmitted. In either case, there are problems if the command or the | |
9150 | acknowledgment packet is dropped.} Stan: @emph{If people really wanted | |
9151 | to add something like this, and get it working for the first time, they | |
9152 | ought to modify ser-unix.c to send some kind of out-of-band message to a | |
9153 | specially-setup stub and have the switch happen "in between" packets, so | |
9154 | that from remote protocol's point of view, nothing actually | |
9155 | happened.} | |
9156 | ||
9157 | @item set breakpoint @strong{(deprecated)} | |
9158 | @tab @code{B}@var{addr},@var{mode} | |
9159 | @tab | |
9160 | Set (@var{mode} is @samp{S}) or clear (@var{mode} is @samp{C}) a | |
9161 | breakpoint at @var{addr}. @emph{This has been replaced by the @samp{Z} and | |
9162 | @samp{z} packets.} | |
9163 | ||
9164 | @item continue | |
9165 | @tab @code{c}@var{addr} | |
9166 | @tab | |
9167 | @var{addr} is address to resume. If @var{addr} is omitted, resume at | |
9168 | current address. | |
9169 | @item | |
9170 | @tab reply | |
9171 | @tab see below | |
9172 | ||
f1251bdd | 9173 | @item continue with signal |
104c1213 JM |
9174 | @tab @code{C}@var{sig}@code{;}@var{addr} |
9175 | @tab | |
9176 | Continue with signal @var{sig} (hex signal number). If | |
9177 | @code{;}@var{addr} is omitted, resume at same address. | |
9178 | @item | |
9179 | @tab reply | |
9180 | @tab see below | |
9181 | ||
598ca718 | 9182 | @item toggle debug @strong{(deprecated)} |
104c1213 JM |
9183 | @tab @code{d} |
9184 | @tab | |
d4f3574e | 9185 | toggle debug flag. |
104c1213 | 9186 | |
f1251bdd | 9187 | @item detach |
104c1213 | 9188 | @tab @code{D} |
d4f3574e | 9189 | @tab |
2df3850c JM |
9190 | Detach @value{GDBN} from the remote system. Sent to the remote target before |
9191 | @value{GDBN} disconnects. | |
d4f3574e SS |
9192 | @item |
9193 | @tab reply @emph{no response} | |
9194 | @tab | |
598ca718 | 9195 | @value{GDBN} does not check for any response after sending this packet. |
104c1213 JM |
9196 | |
9197 | @item reserved | |
9198 | @tab @code{e} | |
5d161b24 | 9199 | @tab Reserved for future use |
104c1213 JM |
9200 | |
9201 | @item reserved | |
9202 | @tab @code{E} | |
5d161b24 | 9203 | @tab Reserved for future use |
104c1213 JM |
9204 | |
9205 | @item reserved | |
9206 | @tab @code{f} | |
5d161b24 | 9207 | @tab Reserved for future use |
104c1213 JM |
9208 | |
9209 | @item reserved | |
9210 | @tab @code{F} | |
5d161b24 | 9211 | @tab Reserved for future use |
104c1213 JM |
9212 | |
9213 | @item read registers | |
9214 | @tab @code{g} | |
9215 | @tab Read general registers. | |
9216 | @item | |
9217 | @tab reply @var{XX...} | |
9218 | @tab | |
9219 | Each byte of register data is described by two hex digits. The bytes | |
9220 | with the register are transmitted in target byte order. The size of | |
d4f3574e | 9221 | each register and their position within the @samp{g} @var{packet} are |
2df3850c | 9222 | determined by the @value{GDBN} internal macros @var{REGISTER_RAW_SIZE} and |
d4f3574e SS |
9223 | @var{REGISTER_NAME} macros. The specification of several standard |
9224 | @code{g} packets is specified below. | |
104c1213 JM |
9225 | @item |
9226 | @tab @code{E}@var{NN} | |
9227 | @tab for an error. | |
9228 | ||
9229 | @item write regs | |
9230 | @tab @code{G}@var{XX...} | |
9231 | @tab | |
9232 | See @samp{g} for a description of the @var{XX...} data. | |
9233 | @item | |
9234 | @tab reply @code{OK} | |
9235 | @tab for success | |
9236 | @item | |
9237 | @tab reply @code{E}@var{NN} | |
9238 | @tab for an error | |
9239 | ||
9240 | @item reserved | |
9241 | @tab @code{h} | |
5d161b24 | 9242 | @tab Reserved for future use |
104c1213 | 9243 | |
f1251bdd | 9244 | @item set thread |
104c1213 JM |
9245 | @tab @code{H}@var{c}@var{t...} |
9246 | @tab | |
d4f3574e SS |
9247 | Set thread for subsequent operations (@samp{m}, @samp{M}, @samp{g}, |
9248 | @samp{G}, et.al.). @var{c} = @samp{c} for thread used in step and | |
9249 | continue; @var{t...} can be -1 for all threads. @var{c} = @samp{g} for | |
9250 | thread used in other operations. If zero, pick a thread, any thread. | |
104c1213 JM |
9251 | @item |
9252 | @tab reply @code{OK} | |
9253 | @tab for success | |
9254 | @item | |
9255 | @tab reply @code{E}@var{NN} | |
9256 | @tab for an error | |
9257 | ||
d4f3574e SS |
9258 | @c FIXME: JTC: |
9259 | @c 'H': How restrictive (or permissive) is the thread model. If a | |
5d161b24 | 9260 | @c thread is selected and stopped, are other threads allowed |
d4f3574e SS |
9261 | @c to continue to execute? As I mentioned above, I think the |
9262 | @c semantics of each command when a thread is selected must be | |
9263 | @c described. For example: | |
9264 | @c | |
9265 | @c 'g': If the stub supports threads and a specific thread is | |
9266 | @c selected, returns the register block from that thread; | |
9267 | @c otherwise returns current registers. | |
9268 | @c | |
9269 | @c 'G' If the stub supports threads and a specific thread is | |
9270 | @c selected, sets the registers of the register block of | |
9271 | @c that thread; otherwise sets current registers. | |
9272 | ||
f1251bdd | 9273 | @item cycle step @strong{(draft)} |
104c1213 JM |
9274 | @tab @code{i}@var{addr}@code{,}@var{nnn} |
9275 | @tab | |
9276 | Step the remote target by a single clock cycle. If @code{,}@var{nnn} is | |
9277 | present, cycle step @var{nnn} cycles. If @var{addr} is present, cycle | |
9278 | step starting at that address. | |
9279 | ||
f1251bdd | 9280 | @item signal then cycle step @strong{(reserved)} |
104c1213 JM |
9281 | @tab @code{I} |
9282 | @tab | |
9283 | See @samp{i} and @samp{S} for likely syntax and semantics. | |
9284 | ||
9285 | @item reserved | |
9286 | @tab @code{j} | |
9287 | @tab Reserved for future use | |
9288 | ||
9289 | @item reserved | |
9290 | @tab @code{J} | |
5d161b24 | 9291 | @tab Reserved for future use |
104c1213 | 9292 | |
f1251bdd | 9293 | @item kill request |
104c1213 JM |
9294 | @tab @code{k} |
9295 | @tab | |
d4f3574e SS |
9296 | FIXME: @emph{There is no description of how operate when a specific |
9297 | thread context has been selected (ie. does 'k' kill only that thread?)}. | |
104c1213 JM |
9298 | |
9299 | @item reserved | |
9300 | @tab @code{l} | |
5d161b24 | 9301 | @tab Reserved for future use |
104c1213 JM |
9302 | |
9303 | @item reserved | |
9304 | @tab @code{L} | |
5d161b24 | 9305 | @tab Reserved for future use |
104c1213 JM |
9306 | |
9307 | @item read memory | |
9308 | @tab @code{m}@var{addr}@code{,}@var{length} | |
9309 | @tab | |
9310 | Read @var{length} bytes of memory starting at address @var{addr}. | |
2df3850c | 9311 | Neither @value{GDBN} nor the stub assume that sized memory transfers are assumed |
d4f3574e SS |
9312 | using word alligned accesses. FIXME: @emph{A word aligned memory |
9313 | transfer mechanism is needed.} | |
104c1213 JM |
9314 | @item |
9315 | @tab reply @var{XX...} | |
9316 | @tab | |
d4f3574e | 9317 | @var{XX...} is mem contents. Can be fewer bytes than requested if able |
2df3850c | 9318 | to read only part of the data. Neither @value{GDBN} nor the stub assume that |
d4f3574e SS |
9319 | sized memory transfers are assumed using word alligned accesses. FIXME: |
9320 | @emph{A word aligned memory transfer mechanism is needed.} | |
104c1213 JM |
9321 | @item |
9322 | @tab reply @code{E}@var{NN} | |
9323 | @tab @var{NN} is errno | |
9324 | ||
9325 | @item write mem | |
9326 | @tab @code{M}@var{addr},@var{length}@code{:}@var{XX...} | |
9327 | @tab | |
9328 | Write @var{length} bytes of memory starting at address @var{addr}. | |
9329 | @var{XX...} is the data. | |
9330 | @item | |
9331 | @tab reply @code{OK} | |
9332 | @tab for success | |
9333 | @item | |
9334 | @tab reply @code{E}@var{NN} | |
9335 | @tab | |
9336 | for an error (this includes the case where only part of the data was | |
9337 | written). | |
9338 | ||
9339 | @item reserved | |
9340 | @tab @code{n} | |
5d161b24 | 9341 | @tab Reserved for future use |
104c1213 JM |
9342 | |
9343 | @item reserved | |
9344 | @tab @code{N} | |
5d161b24 | 9345 | @tab Reserved for future use |
104c1213 JM |
9346 | |
9347 | @item reserved | |
9348 | @tab @code{o} | |
5d161b24 | 9349 | @tab Reserved for future use |
104c1213 JM |
9350 | |
9351 | @item reserved | |
9352 | @tab @code{O} | |
5d161b24 | 9353 | @tab Reserved for future use |
104c1213 JM |
9354 | |
9355 | @item read reg @strong{(reserved)} | |
9356 | @tab @code{p}@var{n...} | |
9357 | @tab | |
9358 | See write register. | |
9359 | @item | |
9360 | @tab return @var{r....} | |
9361 | @tab The hex encoded value of the register in target byte order. | |
9362 | ||
f1251bdd | 9363 | @item write reg |
104c1213 JM |
9364 | @tab @code{P}@var{n...}@code{=}@var{r...} |
9365 | @tab | |
9366 | Write register @var{n...} with value @var{r...}, which contains two hex | |
9367 | digits for each byte in the register (target byte order). | |
9368 | @item | |
9369 | @tab reply @code{OK} | |
9370 | @tab for success | |
9371 | @item | |
9372 | @tab reply @code{E}@var{NN} | |
9373 | @tab for an error | |
9374 | ||
f1251bdd | 9375 | @item general query |
104c1213 JM |
9376 | @tab @code{q}@var{query} |
9377 | @tab | |
598ca718 | 9378 | Request info about @var{query}. In general @value{GDBN} queries |
104c1213 | 9379 | have a leading upper case letter. Custom vendor queries should use a |
d4f3574e SS |
9380 | company prefix (in lower case) ex: @samp{qfsf.var}. @var{query} may |
9381 | optionally be followed by a @samp{,} or @samp{;} separated list. Stubs | |
9382 | must ensure that they match the full @var{query} name. | |
104c1213 JM |
9383 | @item |
9384 | @tab reply @code{XX...} | |
d4f3574e | 9385 | @tab Hex encoded data from query. The reply can not be empty. |
104c1213 JM |
9386 | @item |
9387 | @tab reply @code{E}@var{NN} | |
9388 | @tab error reply | |
9389 | @item | |
9390 | @tab reply @samp{} | |
9391 | @tab Indicating an unrecognized @var{query}. | |
9392 | ||
f1251bdd | 9393 | @item general set |
104c1213 JM |
9394 | @tab @code{Q}@var{var}@code{=}@var{val} |
9395 | @tab | |
9396 | Set value of @var{var} to @var{val}. See @samp{q} for a discussing of | |
9397 | naming conventions. | |
9398 | ||
598ca718 | 9399 | @item reset @strong{(deprecated)} |
d4f3574e SS |
9400 | @tab @code{r} |
9401 | @tab | |
9402 | Reset the entire system. | |
104c1213 | 9403 | |
f1251bdd | 9404 | @item remote restart |
104c1213 JM |
9405 | @tab @code{R}@var{XX} |
9406 | @tab | |
d4f3574e SS |
9407 | Restart the remote server. @var{XX} while needed has no clear |
9408 | definition. FIXME: @emph{An example interaction explaining how this | |
9409 | packet is used in extended-remote mode is needed}. | |
104c1213 | 9410 | |
f1251bdd | 9411 | @item step |
104c1213 JM |
9412 | @tab @code{s}@var{addr} |
9413 | @tab | |
9414 | @var{addr} is address to resume. If @var{addr} is omitted, resume at | |
9415 | same address. | |
9416 | @item | |
9417 | @tab reply | |
9418 | @tab see below | |
9419 | ||
f1251bdd | 9420 | @item step with signal |
104c1213 JM |
9421 | @tab @code{S}@var{sig}@code{;}@var{addr} |
9422 | @tab | |
9423 | Like @samp{C} but step not continue. | |
9424 | @item | |
9425 | @tab reply | |
9426 | @tab see below | |
9427 | ||
f1251bdd | 9428 | @item search |
104c1213 JM |
9429 | @tab @code{t}@var{addr}@code{:}@var{PP}@code{,}@var{MM} |
9430 | @tab | |
9431 | Search backwards starting at address @var{addr} for a match with pattern | |
9432 | @var{PP} and mask @var{MM}. @var{PP} and @var{MM} are 4 | |
d4f3574e | 9433 | bytes. @var{addr} must be at least 3 digits. |
104c1213 | 9434 | |
f1251bdd | 9435 | @item thread alive |
104c1213 JM |
9436 | @tab @code{T}@var{XX} |
9437 | @tab Find out if the thread XX is alive. | |
9438 | @item | |
9439 | @tab reply @code{OK} | |
9440 | @tab thread is still alive | |
9441 | @item | |
9442 | @tab reply @code{E}@var{NN} | |
9443 | @tab thread is dead | |
5d161b24 | 9444 | |
104c1213 JM |
9445 | @item reserved |
9446 | @tab @code{u} | |
5d161b24 | 9447 | @tab Reserved for future use |
104c1213 JM |
9448 | |
9449 | @item reserved | |
9450 | @tab @code{U} | |
5d161b24 | 9451 | @tab Reserved for future use |
104c1213 JM |
9452 | |
9453 | @item reserved | |
9454 | @tab @code{v} | |
5d161b24 | 9455 | @tab Reserved for future use |
104c1213 JM |
9456 | |
9457 | @item reserved | |
9458 | @tab @code{V} | |
5d161b24 | 9459 | @tab Reserved for future use |
104c1213 JM |
9460 | |
9461 | @item reserved | |
9462 | @tab @code{w} | |
5d161b24 | 9463 | @tab Reserved for future use |
104c1213 JM |
9464 | |
9465 | @item reserved | |
9466 | @tab @code{W} | |
5d161b24 | 9467 | @tab Reserved for future use |
104c1213 JM |
9468 | |
9469 | @item reserved | |
9470 | @tab @code{x} | |
5d161b24 | 9471 | @tab Reserved for future use |
104c1213 | 9472 | |
f1251bdd | 9473 | @item write mem (binary) |
104c1213 JM |
9474 | @tab @code{X}@var{addr}@code{,}@var{length}@var{:}@var{XX...} |
9475 | @tab | |
9476 | @var{addr} is address, @var{length} is number of bytes, @var{XX...} is | |
d4f3574e SS |
9477 | binary data. The characters @code{$}, @code{#}, and @code{0x7d} are |
9478 | escaped using @code{0x7d}. | |
104c1213 JM |
9479 | @item |
9480 | @tab reply @code{OK} | |
9481 | @tab for success | |
9482 | @item | |
9483 | @tab reply @code{E}@var{NN} | |
9484 | @tab for an error | |
9485 | ||
9486 | @item reserved | |
9487 | @tab @code{y} | |
5d161b24 | 9488 | @tab Reserved for future use |
104c1213 JM |
9489 | |
9490 | @item reserved | |
9491 | @tab @code{Y} | |
5d161b24 | 9492 | @tab Reserved for future use |
104c1213 | 9493 | |
f1251bdd | 9494 | @item remove break or watchpoint @strong{(draft)} |
104c1213 JM |
9495 | @tab @code{z}@var{t}@code{,}@var{addr}@code{,}@var{length} |
9496 | @tab | |
9497 | See @samp{Z}. | |
9498 | ||
f1251bdd | 9499 | @item insert break or watchpoint @strong{(draft)} |
104c1213 JM |
9500 | @tab @code{Z}@var{t}@code{,}@var{addr}@code{,}@var{length} |
9501 | @tab | |
9502 | @var{t} is type: @samp{0} - software breakpoint, @samp{1} - hardware | |
9503 | breakpoint, @samp{2} - write watchpoint, @samp{3} - read watchpoint, | |
9504 | @samp{4} - access watchpoint; @var{addr} is address; @var{length} is in | |
9505 | bytes. For a software breakpoint, @var{length} specifies the size of | |
9506 | the instruction to be patched. For hardware breakpoints and watchpoints | |
d4f3574e SS |
9507 | @var{length} specifies the memory region to be monitored. To avoid |
9508 | potential problems with duplicate packets, the operations should be | |
6d2ebf8b | 9509 | implemented in an idempotent way. |
104c1213 JM |
9510 | @item |
9511 | @tab reply @code{E}@var{NN} | |
9512 | @tab for an error | |
9513 | @item | |
9514 | @tab reply @code{OK} | |
9515 | @tab for success | |
9516 | @item | |
9517 | @tab @samp{} | |
9518 | @tab If not supported. | |
9519 | ||
9520 | @item reserved | |
9521 | @tab <other> | |
5d161b24 | 9522 | @tab Reserved for future use |
104c1213 JM |
9523 | |
9524 | @end multitable | |
9525 | ||
d4f3574e SS |
9526 | The @samp{C}, @samp{c}, @samp{S}, @samp{s} and @samp{?} packets can |
9527 | receive any of the below as a reply. In the case of the @samp{C}, | |
9528 | @samp{c}, @samp{S} and @samp{s} packets, that reply is only returned | |
9529 | when the target halts. In the below the exact meaning of @samp{signal | |
9530 | number} is poorly defined. In general one of the UNIX signal numbering | |
9531 | conventions is used. | |
104c1213 JM |
9532 | |
9533 | @multitable @columnfractions .4 .6 | |
9534 | ||
9535 | @item @code{S}@var{AA} | |
9536 | @tab @var{AA} is the signal number | |
9537 | ||
9538 | @item @code{T}@var{AA}@var{n...}@code{:}@var{r...}@code{;}@var{n...}@code{:}@var{r...}@code{;}@var{n...}@code{:}@var{r...}@code{;} | |
9539 | @tab | |
9540 | @var{AA} = two hex digit signal number; @var{n...} = register number | |
9541 | (hex), @var{r...} = target byte ordered register contents, size defined | |
9542 | by @code{REGISTER_RAW_SIZE}; @var{n...} = @samp{thread}, @var{r...} = | |
9543 | thread process ID, this is a hex integer; @var{n...} = other string not | |
d4f3574e | 9544 | starting with valid hex digit. @value{GDBN} should ignore this |
104c1213 JM |
9545 | @var{n...}, @var{r...} pair and go on to the next. This way we can |
9546 | extend the protocol. | |
9547 | ||
9548 | @item @code{W}@var{AA} | |
9549 | @tab | |
9550 | The process exited, and @var{AA} is the exit status. This is only | |
9551 | applicable for certains sorts of targets. | |
9552 | ||
9553 | @item @code{X}@var{AA} | |
9554 | @tab | |
9555 | The process terminated with signal @var{AA}. | |
9556 | ||
6d2ebf8b | 9557 | @item @code{N}@var{AA}@code{;}@var{t...}@code{;}@var{d...}@code{;}@var{b...} @strong{(obsolete)} |
104c1213 | 9558 | @tab |
6d2ebf8b SS |
9559 | @var{AA} = signal number; @var{t...} = address of symbol "_start"; |
9560 | @var{d...} = base of data section; @var{b...} = base of bss section. | |
9561 | @emph{Note: only used by Cisco Systems targets. The difference between | |
9562 | this reply and the "qOffsets" query is that the 'N' packet may arrive | |
9563 | spontaneously whereas the 'qOffsets' is a query initiated by the host | |
9564 | debugger.} | |
104c1213 JM |
9565 | |
9566 | @item @code{O}@var{XX...} | |
9567 | @tab | |
c3f6f71d | 9568 | @var{XX...} is hex encoding of @sc{ascii} data. This can happen at any time |
104c1213 JM |
9569 | while the program is running and the debugger should continue to wait |
9570 | for 'W', 'T', etc. | |
9571 | ||
9572 | @end multitable | |
9573 | ||
d4f3574e SS |
9574 | The following set and query packets have already been defined. |
9575 | ||
9576 | @multitable @columnfractions .2 .2 .6 | |
9577 | ||
9578 | @item current thread | |
9579 | @tab @code{q}@code{C} | |
9580 | @tab Return the current thread id. | |
9581 | @item | |
9582 | @tab reply @code{QC}@var{pid} | |
9583 | @tab | |
9584 | Where @var{pid} is a HEX encoded 16 bit process id. | |
9585 | @item | |
9586 | @tab reply * | |
9587 | @tab Any other reply implies the old pid. | |
9588 | ||
bba2971c MS |
9589 | @item all thread ids |
9590 | @tab @code{q}@code{fThreadInfo} | |
9591 | @item | |
9592 | @tab @code{q}@code{sThreadInfo} | |
d4f3574e | 9593 | @tab |
bba2971c MS |
9594 | Obtain a list of active thread ids from the target (OS). Since there |
9595 | may be too many active threads to fit into one reply packet, this query | |
9596 | works iteratively: it may require more than one query/reply sequence to | |
9597 | obtain the entire list of threads. The first query of the sequence will | |
5d161b24 | 9598 | be the @code{qf}@code{ThreadInfo} query; subsequent queries in the |
bba2971c | 9599 | sequence will be the @code{qs}@code{ThreadInfo} query. |
d4f3574e | 9600 | @item |
bba2971c MS |
9601 | @tab |
9602 | @tab NOTE: replaces the @code{qL} query (see below). | |
d4f3574e | 9603 | @item |
5d161b24 | 9604 | @tab reply @code{m}@var{<id>} |
bba2971c MS |
9605 | @tab A single thread id |
9606 | @item | |
00e4a2e4 | 9607 | @tab reply @code{m}@var{<id>},@var{<id>...} |
bba2971c MS |
9608 | @tab a comma-separated list of thread ids |
9609 | @item | |
9610 | @tab reply @code{l} | |
9611 | @tab (lower case 'el') denotes end of list. | |
9612 | @item | |
9613 | @tab | |
9614 | @tab | |
9615 | In response to each query, the target will reply with a list of one | |
9616 | or more thread ids, in big-endian hex, separated by commas. GDB will | |
9617 | respond to each reply with a request for more thread ids (using the | |
9618 | @code{qs} form of the query), until the target responds with @code{l} | |
9619 | (lower-case el, for @code{'last'}). | |
9620 | ||
9621 | @item extra thread info | |
480ff1fb | 9622 | @tab @code{q}@code{ThreadExtraInfo}@code{,}@var{id} |
bba2971c MS |
9623 | @tab |
9624 | @item | |
9625 | @tab | |
9626 | @tab | |
9627 | Where @var{<id>} is a thread-id in big-endian hex. | |
9628 | Obtain a printable string description of a thread's attributes from | |
9629 | the target OS. This string may contain anything that the target OS | |
9630 | thinks is interesting for @value{GDBN} to tell the user about the thread. | |
9631 | The string is displayed in @value{GDBN}'s @samp{info threads} display. | |
5d161b24 | 9632 | Some examples of possible thread extra info strings are "Runnable", or |
bba2971c MS |
9633 | "Blocked on Mutex". |
9634 | @item | |
9635 | @tab reply @var{XX...} | |
9636 | @tab | |
9637 | Where @var{XX...} is a hex encoding of @sc{ascii} data, comprising the | |
9638 | printable string containing the extra information about the thread's | |
9639 | attributes. | |
d4f3574e SS |
9640 | |
9641 | @item query @var{LIST} or @var{threadLIST} @strong{(deprecated)} | |
9642 | @tab @code{q}@code{L}@var{startflag}@var{threadcount}@var{nextthread} | |
9643 | @tab | |
2b628194 MS |
9644 | @item |
9645 | @tab | |
9646 | @tab | |
d4f3574e SS |
9647 | Obtain thread information from RTOS. Where: @var{startflag} (one hex |
9648 | digit) is one to indicate the first query and zero to indicate a | |
9649 | subsequent query; @var{threadcount} (two hex digits) is the maximum | |
9650 | number of threads the response packet can contain; and @var{nextthread} | |
9651 | (eight hex digits), for subsequent queries (@var{startflag} is zero), is | |
9652 | returned in the response as @var{argthread}. | |
9653 | @item | |
bba2971c MS |
9654 | @tab |
9655 | @tab NOTE: this query is replaced by the @code{q}@code{fThreadInfo} | |
9656 | query (see above). | |
9657 | @item | |
d4f3574e SS |
9658 | @tab reply @code{q}@code{M}@var{count}@var{done}@var{argthread}@var{thread...} |
9659 | @tab | |
2b628194 MS |
9660 | @item |
9661 | @tab | |
9662 | @tab | |
d4f3574e SS |
9663 | Where: @var{count} (two hex digits) is the number of threads being |
9664 | returned; @var{done} (one hex digit) is zero to indicate more threads | |
9665 | and one indicates no further threads; @var{argthreadid} (eight hex | |
9666 | digits) is @var{nextthread} from the request packet; @var{thread...} is | |
9667 | a sequence of thread IDs from the target. @var{threadid} (eight hex | |
9668 | digits). See @code{remote.c:parse_threadlist_response()}. | |
9669 | ||
bba2971c MS |
9670 | @item compute CRC of memory block |
9671 | @tab @code{q}@code{CRC:}@var{addr}@code{,}@var{length} | |
9672 | @tab | |
9673 | @item | |
9674 | @tab reply @code{E}@var{NN} | |
9675 | @tab An error (such as memory fault) | |
9676 | @item | |
9677 | @tab reply @code{C}@var{CRC32} | |
9678 | @tab A 32 bit cyclic redundancy check of the specified memory region. | |
9679 | ||
d4f3574e SS |
9680 | @item query sect offs |
9681 | @tab @code{q}@code{Offsets} | |
917317f4 JM |
9682 | @tab |
9683 | Get section offsets that the target used when re-locating the downloaded | |
9684 | image. @emph{Note: while a @code{Bss} offset is included in the | |
9685 | response, @value{GDBN} ignores this and instead applies the @code{Data} | |
9686 | offset to the @code{Bss} section.} | |
d4f3574e SS |
9687 | @item |
9688 | @tab reply @code{Text=}@var{xxx}@code{;Data=}@var{yyy}@code{;Bss=}@var{zzz} | |
9689 | ||
9690 | @item thread info request | |
9691 | @tab @code{q}@code{P}@var{mode}@var{threadid} | |
9692 | @tab | |
598ca718 EZ |
9693 | @item |
9694 | @tab | |
9695 | @tab | |
d4f3574e SS |
9696 | Returns information on @var{threadid}. Where: @var{mode} is a hex |
9697 | encoded 32 bit mode; @var{threadid} is a hex encoded 64 bit thread ID. | |
9698 | @item | |
9699 | @tab reply * | |
9700 | @tab | |
9701 | See @code{remote.c:remote_unpack_thread_info_response()}. | |
9702 | ||
9703 | @item remote command | |
9704 | @tab @code{q}@code{Rcmd,}@var{COMMAND} | |
9705 | @tab | |
598ca718 EZ |
9706 | @item |
9707 | @tab | |
9708 | @tab | |
d4f3574e SS |
9709 | @var{COMMAND} (hex encoded) is passed to the local interpreter for |
9710 | execution. Invalid commands should be reported using the output string. | |
9711 | Before the final result packet, the target may also respond with a | |
9712 | number of intermediate @code{O}@var{OUTPUT} console output | |
9713 | packets. @emph{Implementors should note that providing access to a | |
9714 | stubs's interpreter may have security implications}. | |
9715 | @item | |
9716 | @tab reply @code{OK} | |
9717 | @tab | |
9718 | A command response with no output. | |
9719 | @item | |
9720 | @tab reply @var{OUTPUT} | |
9721 | @tab | |
9722 | A command response with the hex encoded output string @var{OUTPUT}. | |
9723 | @item | |
9724 | @tab reply @code{E}@var{NN} | |
9725 | @tab | |
9726 | Indicate a badly formed request. | |
9727 | ||
9728 | @item | |
9729 | @tab reply @samp{} | |
9730 | @tab | |
9731 | When @samp{q}@samp{Rcmd} is not recognized. | |
9732 | ||
9733 | @end multitable | |
9734 | ||
9735 | The following @samp{g}/@samp{G} packets have previously been defined. | |
9736 | In the below, some thirty-two bit registers are transferred as sixty-four | |
9737 | bits. Those registers should be zero/sign extended (which?) to fill the | |
9738 | space allocated. Register bytes are transfered in target byte order. | |
9739 | The two nibbles within a register byte are transfered most-significant - | |
9740 | least-significant. | |
9741 | ||
9742 | @multitable @columnfractions .5 .5 | |
9743 | ||
9744 | @item MIPS32 | |
9745 | @tab | |
9746 | All registers are transfered as thirty-two bit quantities in the order: | |
9747 | 32 general-purpose; sr; lo; hi; bad; cause; pc; 32 floating-point | |
9748 | registers; fsr; fir; fp. | |
9749 | ||
9750 | @item MIPS64 | |
9751 | @tab | |
9752 | All registers are transfered as sixty-four bit quantities (including | |
9753 | thirty-two bit registers such as @code{sr}). The ordering is the same | |
9754 | as @code{MIPS32}. | |
9755 | ||
9756 | @end multitable | |
9757 | ||
104c1213 JM |
9758 | Example sequence of a target being re-started. Notice how the restart |
9759 | does not get any direct output: | |
9760 | ||
9761 | @example | |
9762 | <- @code{R00} | |
9763 | -> @code{+} | |
9764 | @emph{target restarts} | |
9765 | <- @code{?} | |
9766 | -> @code{+} | |
9767 | -> @code{T001:1234123412341234} | |
9768 | <- @code{+} | |
9769 | @end example | |
9770 | ||
9771 | Example sequence of a target being stepped by a single instruction: | |
9772 | ||
9773 | @example | |
9774 | <- @code{G1445...} | |
9775 | -> @code{+} | |
9776 | <- @code{s} | |
9777 | -> @code{+} | |
9778 | @emph{time passes} | |
9779 | -> @code{T001:1234123412341234} | |
9780 | <- @code{+} | |
9781 | <- @code{g} | |
9782 | -> @code{+} | |
9783 | -> @code{1455...} | |
9784 | <- @code{+} | |
9785 | @end example | |
9786 | ||
6d2ebf8b | 9787 | @node Server |
104c1213 JM |
9788 | @subsubsection Using the @code{gdbserver} program |
9789 | ||
9790 | @kindex gdbserver | |
9791 | @cindex remote connection without stubs | |
9792 | @code{gdbserver} is a control program for Unix-like systems, which | |
9793 | allows you to connect your program with a remote @value{GDBN} via | |
9794 | @code{target remote}---but without linking in the usual debugging stub. | |
9795 | ||
9796 | @code{gdbserver} is not a complete replacement for the debugging stubs, | |
9797 | because it requires essentially the same operating-system facilities | |
9798 | that @value{GDBN} itself does. In fact, a system that can run | |
9799 | @code{gdbserver} to connect to a remote @value{GDBN} could also run | |
9800 | @value{GDBN} locally! @code{gdbserver} is sometimes useful nevertheless, | |
9801 | because it is a much smaller program than @value{GDBN} itself. It is | |
9802 | also easier to port than all of @value{GDBN}, so you may be able to get | |
9803 | started more quickly on a new system by using @code{gdbserver}. | |
9804 | Finally, if you develop code for real-time systems, you may find that | |
9805 | the tradeoffs involved in real-time operation make it more convenient to | |
9806 | do as much development work as possible on another system, for example | |
9807 | by cross-compiling. You can use @code{gdbserver} to make a similar | |
9808 | choice for debugging. | |
9809 | ||
9810 | @value{GDBN} and @code{gdbserver} communicate via either a serial line | |
9811 | or a TCP connection, using the standard @value{GDBN} remote serial | |
9812 | protocol. | |
9813 | ||
9814 | @table @emph | |
9815 | @item On the target machine, | |
9816 | you need to have a copy of the program you want to debug. | |
9817 | @code{gdbserver} does not need your program's symbol table, so you can | |
9818 | strip the program if necessary to save space. @value{GDBN} on the host | |
9819 | system does all the symbol handling. | |
9820 | ||
9821 | To use the server, you must tell it how to communicate with @value{GDBN}; | |
9822 | the name of your program; and the arguments for your program. The | |
9823 | syntax is: | |
9824 | ||
9825 | @smallexample | |
9826 | target> gdbserver @var{comm} @var{program} [ @var{args} @dots{} ] | |
9827 | @end smallexample | |
9828 | ||
9829 | @var{comm} is either a device name (to use a serial line) or a TCP | |
9830 | hostname and portnumber. For example, to debug Emacs with the argument | |
9831 | @samp{foo.txt} and communicate with @value{GDBN} over the serial port | |
9832 | @file{/dev/com1}: | |
9833 | ||
9834 | @smallexample | |
9835 | target> gdbserver /dev/com1 emacs foo.txt | |
9836 | @end smallexample | |
9837 | ||
9838 | @code{gdbserver} waits passively for the host @value{GDBN} to communicate | |
9839 | with it. | |
9840 | ||
9841 | To use a TCP connection instead of a serial line: | |
9842 | ||
9843 | @smallexample | |
9844 | target> gdbserver host:2345 emacs foo.txt | |
9845 | @end smallexample | |
9846 | ||
9847 | The only difference from the previous example is the first argument, | |
9848 | specifying that you are communicating with the host @value{GDBN} via | |
9849 | TCP. The @samp{host:2345} argument means that @code{gdbserver} is to | |
9850 | expect a TCP connection from machine @samp{host} to local TCP port 2345. | |
9851 | (Currently, the @samp{host} part is ignored.) You can choose any number | |
9852 | you want for the port number as long as it does not conflict with any | |
9853 | TCP ports already in use on the target system (for example, @code{23} is | |
9854 | reserved for @code{telnet}).@footnote{If you choose a port number that | |
9855 | conflicts with another service, @code{gdbserver} prints an error message | |
d4f3574e | 9856 | and exits.} You must use the same port number with the host @value{GDBN} |
104c1213 JM |
9857 | @code{target remote} command. |
9858 | ||
9859 | @item On the @value{GDBN} host machine, | |
9860 | you need an unstripped copy of your program, since @value{GDBN} needs | |
9861 | symbols and debugging information. Start up @value{GDBN} as usual, | |
9862 | using the name of the local copy of your program as the first argument. | |
9863 | (You may also need the @w{@samp{--baud}} option if the serial line is | |
d4f3574e | 9864 | running at anything other than 9600@dmn{bps}.) After that, use @code{target |
104c1213 JM |
9865 | remote} to establish communications with @code{gdbserver}. Its argument |
9866 | is either a device name (usually a serial device, like | |
9867 | @file{/dev/ttyb}), or a TCP port descriptor in the form | |
9868 | @code{@var{host}:@var{PORT}}. For example: | |
9869 | ||
9870 | @smallexample | |
9871 | (@value{GDBP}) target remote /dev/ttyb | |
9872 | @end smallexample | |
9873 | ||
9874 | @noindent | |
9875 | communicates with the server via serial line @file{/dev/ttyb}, and | |
9876 | ||
9877 | @smallexample | |
9878 | (@value{GDBP}) target remote the-target:2345 | |
9879 | @end smallexample | |
9880 | ||
9881 | @noindent | |
9882 | communicates via a TCP connection to port 2345 on host @w{@file{the-target}}. | |
9883 | For TCP connections, you must start up @code{gdbserver} prior to using | |
9884 | the @code{target remote} command. Otherwise you may get an error whose | |
9885 | text depends on the host system, but which usually looks something like | |
9886 | @samp{Connection refused}. | |
9887 | @end table | |
9888 | ||
6d2ebf8b | 9889 | @node NetWare |
104c1213 JM |
9890 | @subsubsection Using the @code{gdbserve.nlm} program |
9891 | ||
9892 | @kindex gdbserve.nlm | |
9893 | @code{gdbserve.nlm} is a control program for NetWare systems, which | |
9894 | allows you to connect your program with a remote @value{GDBN} via | |
9895 | @code{target remote}. | |
9896 | ||
9897 | @value{GDBN} and @code{gdbserve.nlm} communicate via a serial line, | |
9898 | using the standard @value{GDBN} remote serial protocol. | |
9899 | ||
9900 | @table @emph | |
9901 | @item On the target machine, | |
9902 | you need to have a copy of the program you want to debug. | |
9903 | @code{gdbserve.nlm} does not need your program's symbol table, so you | |
9904 | can strip the program if necessary to save space. @value{GDBN} on the | |
9905 | host system does all the symbol handling. | |
9906 | ||
9907 | To use the server, you must tell it how to communicate with | |
9908 | @value{GDBN}; the name of your program; and the arguments for your | |
9909 | program. The syntax is: | |
9910 | ||
5d161b24 | 9911 | @smallexample |
104c1213 JM |
9912 | load gdbserve [ BOARD=@var{board} ] [ PORT=@var{port} ] |
9913 | [ BAUD=@var{baud} ] @var{program} [ @var{args} @dots{} ] | |
9914 | @end smallexample | |
9915 | ||
9916 | @var{board} and @var{port} specify the serial line; @var{baud} specifies | |
9917 | the baud rate used by the connection. @var{port} and @var{node} default | |
d4f3574e | 9918 | to 0, @var{baud} defaults to 9600@dmn{bps}. |
104c1213 JM |
9919 | |
9920 | For example, to debug Emacs with the argument @samp{foo.txt}and | |
5d161b24 | 9921 | communicate with @value{GDBN} over serial port number 2 or board 1 |
d4f3574e | 9922 | using a 19200@dmn{bps} connection: |
104c1213 JM |
9923 | |
9924 | @smallexample | |
9925 | load gdbserve BOARD=1 PORT=2 BAUD=19200 emacs foo.txt | |
9926 | @end smallexample | |
9927 | ||
9928 | @item On the @value{GDBN} host machine, | |
9929 | you need an unstripped copy of your program, since @value{GDBN} needs | |
9930 | symbols and debugging information. Start up @value{GDBN} as usual, | |
9931 | using the name of the local copy of your program as the first argument. | |
9932 | (You may also need the @w{@samp{--baud}} option if the serial line is | |
d4f3574e | 9933 | running at anything other than 9600@dmn{bps}. After that, use @code{target |
104c1213 JM |
9934 | remote} to establish communications with @code{gdbserve.nlm}. Its |
9935 | argument is a device name (usually a serial device, like | |
9936 | @file{/dev/ttyb}). For example: | |
9937 | ||
9938 | @smallexample | |
9939 | (@value{GDBP}) target remote /dev/ttyb | |
9940 | @end smallexample | |
9941 | ||
9942 | @noindent | |
9943 | communications with the server via serial line @file{/dev/ttyb}. | |
9944 | @end table | |
9945 | ||
6d2ebf8b | 9946 | @node KOD |
104c1213 JM |
9947 | @section Kernel Object Display |
9948 | ||
9949 | @cindex kernel object display | |
9950 | @cindex kernel object | |
9951 | @cindex KOD | |
9952 | ||
9953 | Some targets support kernel object display. Using this facility, | |
9954 | @value{GDBN} communicates specially with the underlying operating system | |
9955 | and can display information about operating system-level objects such as | |
9956 | mutexes and other synchronization objects. Exactly which objects can be | |
9957 | displayed is determined on a per-OS basis. | |
9958 | ||
9959 | Use the @code{set os} command to set the operating system. This tells | |
9960 | @value{GDBN} which kernel object display module to initialize: | |
9961 | ||
9962 | @example | |
2df3850c | 9963 | (@value{GDBP}) set os cisco |
104c1213 JM |
9964 | @end example |
9965 | ||
9966 | If @code{set os} succeeds, @value{GDBN} will display some information | |
9967 | about the operating system, and will create a new @code{info} command | |
9968 | which can be used to query the target. The @code{info} command is named | |
9969 | after the operating system: | |
9970 | ||
9971 | @example | |
2df3850c | 9972 | (@value{GDBP}) info cisco |
104c1213 JM |
9973 | List of Cisco Kernel Objects |
9974 | Object Description | |
9975 | any Any and all objects | |
9976 | @end example | |
9977 | ||
9978 | Further subcommands can be used to query about particular objects known | |
9979 | by the kernel. | |
9980 | ||
9981 | There is currently no way to determine whether a given operating system | |
96baa820 JM |
9982 | is supported other than to try it. |
9983 | ||
9984 | ||
6d2ebf8b | 9985 | @node Configurations |
104c1213 JM |
9986 | @chapter Configuration-Specific Information |
9987 | ||
9988 | While nearly all @value{GDBN} commands are available for all native and | |
9989 | cross versions of the debugger, there are some exceptions. This chapter | |
9990 | describes things that are only available in certain configurations. | |
9991 | ||
9992 | There are three major categories of configurations: native | |
9993 | configurations, where the host and target are the same, embedded | |
9994 | operating system configurations, which are usually the same for several | |
9995 | different processor architectures, and bare embedded processors, which | |
9996 | are quite different from each other. | |
9997 | ||
9998 | @menu | |
9999 | * Native:: | |
10000 | * Embedded OS:: | |
10001 | * Embedded Processors:: | |
10002 | * Architectures:: | |
10003 | @end menu | |
10004 | ||
6d2ebf8b | 10005 | @node Native |
104c1213 JM |
10006 | @section Native |
10007 | ||
10008 | This section describes details specific to particular native | |
10009 | configurations. | |
10010 | ||
10011 | @menu | |
10012 | * HP-UX:: HP-UX | |
10013 | * SVR4 Process Information:: SVR4 process information | |
10014 | @end menu | |
10015 | ||
6d2ebf8b | 10016 | @node HP-UX |
104c1213 JM |
10017 | @subsection HP-UX |
10018 | ||
10019 | On HP-UX systems, if you refer to a function or variable name that | |
10020 | begins with a dollar sign, @value{GDBN} searches for a user or system | |
10021 | name first, before it searches for a convenience variable. | |
10022 | ||
6d2ebf8b | 10023 | @node SVR4 Process Information |
104c1213 JM |
10024 | @subsection SVR4 process information |
10025 | ||
10026 | @kindex /proc | |
10027 | @cindex process image | |
10028 | ||
10029 | Many versions of SVR4 provide a facility called @samp{/proc} that can be | |
10030 | used to examine the image of a running process using file-system | |
10031 | subroutines. If @value{GDBN} is configured for an operating system with | |
10032 | this facility, the command @code{info proc} is available to report on | |
10033 | several kinds of information about the process running your program. | |
10034 | @code{info proc} works only on SVR4 systems that include the | |
10035 | @code{procfs} code. This includes OSF/1 (Digital Unix), Solaris, Irix, | |
10036 | and Unixware, but not HP-UX or Linux, for example. | |
10037 | ||
10038 | @table @code | |
10039 | @kindex info proc | |
10040 | @item info proc | |
10041 | Summarize available information about the process. | |
10042 | ||
10043 | @kindex info proc mappings | |
10044 | @item info proc mappings | |
10045 | Report on the address ranges accessible in the program, with information | |
10046 | on whether your program may read, write, or execute each range. | |
10047 | ||
10048 | @kindex info proc times | |
10049 | @item info proc times | |
10050 | Starting time, user CPU time, and system CPU time for your program and | |
10051 | its children. | |
10052 | ||
10053 | @kindex info proc id | |
10054 | @item info proc id | |
10055 | Report on the process IDs related to your program: its own process ID, | |
10056 | the ID of its parent, the process group ID, and the session ID. | |
10057 | ||
10058 | @kindex info proc status | |
10059 | @item info proc status | |
10060 | General information on the state of the process. If the process is | |
10061 | stopped, this report includes the reason for stopping, and any signal | |
10062 | received. | |
10063 | ||
10064 | @item info proc all | |
10065 | Show all the above information about the process. | |
10066 | @end table | |
10067 | ||
6d2ebf8b | 10068 | @node Embedded OS |
104c1213 JM |
10069 | @section Embedded Operating Systems |
10070 | ||
10071 | This section describes configurations involving the debugging of | |
10072 | embedded operating systems that are available for several different | |
10073 | architectures. | |
10074 | ||
10075 | @menu | |
10076 | * VxWorks:: Using @value{GDBN} with VxWorks | |
10077 | @end menu | |
10078 | ||
10079 | @value{GDBN} includes the ability to debug programs running on | |
10080 | various real-time operating systems. | |
10081 | ||
6d2ebf8b | 10082 | @node VxWorks |
104c1213 JM |
10083 | @subsection Using @value{GDBN} with VxWorks |
10084 | ||
10085 | @cindex VxWorks | |
10086 | ||
10087 | @table @code | |
10088 | ||
10089 | @kindex target vxworks | |
10090 | @item target vxworks @var{machinename} | |
10091 | A VxWorks system, attached via TCP/IP. The argument @var{machinename} | |
10092 | is the target system's machine name or IP address. | |
10093 | ||
10094 | @end table | |
10095 | ||
10096 | On VxWorks, @code{load} links @var{filename} dynamically on the | |
10097 | current target system as well as adding its symbols in @value{GDBN}. | |
10098 | ||
10099 | @value{GDBN} enables developers to spawn and debug tasks running on networked | |
10100 | VxWorks targets from a Unix host. Already-running tasks spawned from | |
10101 | the VxWorks shell can also be debugged. @value{GDBN} uses code that runs on | |
10102 | both the Unix host and on the VxWorks target. The program | |
d4f3574e | 10103 | @code{@value{GDBP}} is installed and executed on the Unix host. (It may be |
104c1213 | 10104 | installed with the name @code{vxgdb}, to distinguish it from a |
96a2c332 | 10105 | @value{GDBN} for debugging programs on the host itself.) |
104c1213 JM |
10106 | |
10107 | @table @code | |
10108 | @item VxWorks-timeout @var{args} | |
10109 | @kindex vxworks-timeout | |
5d161b24 DB |
10110 | All VxWorks-based targets now support the option @code{vxworks-timeout}. |
10111 | This option is set by the user, and @var{args} represents the number of | |
10112 | seconds @value{GDBN} waits for responses to rpc's. You might use this if | |
10113 | your VxWorks target is a slow software simulator or is on the far side | |
104c1213 JM |
10114 | of a thin network line. |
10115 | @end table | |
10116 | ||
10117 | The following information on connecting to VxWorks was current when | |
10118 | this manual was produced; newer releases of VxWorks may use revised | |
10119 | procedures. | |
10120 | ||
10121 | @kindex INCLUDE_RDB | |
10122 | To use @value{GDBN} with VxWorks, you must rebuild your VxWorks kernel | |
10123 | to include the remote debugging interface routines in the VxWorks | |
10124 | library @file{rdb.a}. To do this, define @code{INCLUDE_RDB} in the | |
10125 | VxWorks configuration file @file{configAll.h} and rebuild your VxWorks | |
10126 | kernel. The resulting kernel contains @file{rdb.a}, and spawns the | |
10127 | source debugging task @code{tRdbTask} when VxWorks is booted. For more | |
10128 | information on configuring and remaking VxWorks, see the manufacturer's | |
10129 | manual. | |
10130 | @c VxWorks, see the @cite{VxWorks Programmer's Guide}. | |
10131 | ||
10132 | Once you have included @file{rdb.a} in your VxWorks system image and set | |
10133 | your Unix execution search path to find @value{GDBN}, you are ready to | |
96a2c332 SS |
10134 | run @value{GDBN}. From your Unix host, run @code{@value{GDBP}} (or |
10135 | @code{vxgdb}, depending on your installation). | |
104c1213 JM |
10136 | |
10137 | @value{GDBN} comes up showing the prompt: | |
10138 | ||
10139 | @example | |
10140 | (vxgdb) | |
10141 | @end example | |
10142 | ||
10143 | @menu | |
10144 | * VxWorks Connection:: Connecting to VxWorks | |
10145 | * VxWorks Download:: VxWorks download | |
10146 | * VxWorks Attach:: Running tasks | |
10147 | @end menu | |
10148 | ||
6d2ebf8b | 10149 | @node VxWorks Connection |
104c1213 JM |
10150 | @subsubsection Connecting to VxWorks |
10151 | ||
10152 | The @value{GDBN} command @code{target} lets you connect to a VxWorks target on the | |
10153 | network. To connect to a target whose host name is ``@code{tt}'', type: | |
10154 | ||
10155 | @example | |
10156 | (vxgdb) target vxworks tt | |
10157 | @end example | |
10158 | ||
10159 | @need 750 | |
10160 | @value{GDBN} displays messages like these: | |
10161 | ||
10162 | @smallexample | |
5d161b24 | 10163 | Attaching remote machine across net... |
104c1213 JM |
10164 | Connected to tt. |
10165 | @end smallexample | |
10166 | ||
10167 | @need 1000 | |
10168 | @value{GDBN} then attempts to read the symbol tables of any object modules | |
10169 | loaded into the VxWorks target since it was last booted. @value{GDBN} locates | |
10170 | these files by searching the directories listed in the command search | |
10171 | path (@pxref{Environment, ,Your program's environment}); if it fails | |
10172 | to find an object file, it displays a message such as: | |
10173 | ||
10174 | @example | |
10175 | prog.o: No such file or directory. | |
10176 | @end example | |
10177 | ||
10178 | When this happens, add the appropriate directory to the search path with | |
10179 | the @value{GDBN} command @code{path}, and execute the @code{target} | |
10180 | command again. | |
10181 | ||
6d2ebf8b | 10182 | @node VxWorks Download |
104c1213 JM |
10183 | @subsubsection VxWorks download |
10184 | ||
10185 | @cindex download to VxWorks | |
10186 | If you have connected to the VxWorks target and you want to debug an | |
10187 | object that has not yet been loaded, you can use the @value{GDBN} | |
10188 | @code{load} command to download a file from Unix to VxWorks | |
10189 | incrementally. The object file given as an argument to the @code{load} | |
10190 | command is actually opened twice: first by the VxWorks target in order | |
10191 | to download the code, then by @value{GDBN} in order to read the symbol | |
10192 | table. This can lead to problems if the current working directories on | |
10193 | the two systems differ. If both systems have NFS mounted the same | |
10194 | filesystems, you can avoid these problems by using absolute paths. | |
10195 | Otherwise, it is simplest to set the working directory on both systems | |
10196 | to the directory in which the object file resides, and then to reference | |
10197 | the file by its name, without any path. For instance, a program | |
10198 | @file{prog.o} may reside in @file{@var{vxpath}/vw/demo/rdb} in VxWorks | |
10199 | and in @file{@var{hostpath}/vw/demo/rdb} on the host. To load this | |
10200 | program, type this on VxWorks: | |
10201 | ||
10202 | @example | |
10203 | -> cd "@var{vxpath}/vw/demo/rdb" | |
10204 | @end example | |
d4f3574e SS |
10205 | |
10206 | @noindent | |
104c1213 JM |
10207 | Then, in @value{GDBN}, type: |
10208 | ||
10209 | @example | |
5d161b24 | 10210 | (vxgdb) cd @var{hostpath}/vw/demo/rdb |
104c1213 JM |
10211 | (vxgdb) load prog.o |
10212 | @end example | |
10213 | ||
10214 | @value{GDBN} displays a response similar to this: | |
10215 | ||
10216 | @smallexample | |
10217 | Reading symbol data from wherever/vw/demo/rdb/prog.o... done. | |
10218 | @end smallexample | |
10219 | ||
10220 | You can also use the @code{load} command to reload an object module | |
10221 | after editing and recompiling the corresponding source file. Note that | |
10222 | this makes @value{GDBN} delete all currently-defined breakpoints, | |
10223 | auto-displays, and convenience variables, and to clear the value | |
10224 | history. (This is necessary in order to preserve the integrity of | |
d4f3574e | 10225 | debugger's data structures that reference the target system's symbol |
104c1213 JM |
10226 | table.) |
10227 | ||
6d2ebf8b | 10228 | @node VxWorks Attach |
104c1213 JM |
10229 | @subsubsection Running tasks |
10230 | ||
10231 | @cindex running VxWorks tasks | |
10232 | You can also attach to an existing task using the @code{attach} command as | |
10233 | follows: | |
10234 | ||
10235 | @example | |
10236 | (vxgdb) attach @var{task} | |
10237 | @end example | |
10238 | ||
10239 | @noindent | |
10240 | where @var{task} is the VxWorks hexadecimal task ID. The task can be running | |
10241 | or suspended when you attach to it. Running tasks are suspended at | |
10242 | the time of attachment. | |
10243 | ||
6d2ebf8b | 10244 | @node Embedded Processors |
104c1213 JM |
10245 | @section Embedded Processors |
10246 | ||
10247 | This section goes into details specific to particular embedded | |
10248 | configurations. | |
10249 | ||
10250 | @menu | |
10251 | * A29K Embedded:: AMD A29K Embedded | |
10252 | * ARM:: ARM | |
10253 | * H8/300:: Hitachi H8/300 | |
10254 | * H8/500:: Hitachi H8/500 | |
10255 | * i960:: Intel i960 | |
10256 | * M32R/D:: Mitsubishi M32R/D | |
10257 | * M68K:: Motorola M68K | |
10258 | * M88K:: Motorola M88K | |
10259 | * MIPS Embedded:: MIPS Embedded | |
10260 | * PA:: HP PA Embedded | |
10261 | * PowerPC: PowerPC | |
10262 | * SH:: Hitachi SH | |
10263 | * Sparclet:: Tsqware Sparclet | |
10264 | * Sparclite:: Fujitsu Sparclite | |
10265 | * ST2000:: Tandem ST2000 | |
10266 | * Z8000:: Zilog Z8000 | |
10267 | @end menu | |
10268 | ||
6d2ebf8b | 10269 | @node A29K Embedded |
104c1213 JM |
10270 | @subsection AMD A29K Embedded |
10271 | ||
10272 | @menu | |
10273 | * A29K UDI:: | |
10274 | * A29K EB29K:: | |
10275 | * Comms (EB29K):: Communications setup | |
10276 | * gdb-EB29K:: EB29K cross-debugging | |
10277 | * Remote Log:: Remote log | |
10278 | @end menu | |
10279 | ||
10280 | @table @code | |
10281 | ||
10282 | @kindex target adapt | |
10283 | @item target adapt @var{dev} | |
10284 | Adapt monitor for A29K. | |
10285 | ||
10286 | @kindex target amd-eb | |
10287 | @item target amd-eb @var{dev} @var{speed} @var{PROG} | |
10288 | @cindex AMD EB29K | |
10289 | Remote PC-resident AMD EB29K board, attached over serial lines. | |
10290 | @var{dev} is the serial device, as for @code{target remote}; | |
10291 | @var{speed} allows you to specify the linespeed; and @var{PROG} is the | |
10292 | name of the program to be debugged, as it appears to DOS on the PC. | |
10293 | @xref{A29K EB29K, ,EBMON protocol for AMD29K}. | |
10294 | ||
10295 | @end table | |
10296 | ||
6d2ebf8b | 10297 | @node A29K UDI |
104c1213 JM |
10298 | @subsubsection A29K UDI |
10299 | ||
10300 | @cindex UDI | |
10301 | @cindex AMD29K via UDI | |
10302 | ||
10303 | @value{GDBN} supports AMD's UDI (``Universal Debugger Interface'') | |
10304 | protocol for debugging the a29k processor family. To use this | |
10305 | configuration with AMD targets running the MiniMON monitor, you need the | |
10306 | program @code{MONTIP}, available from AMD at no charge. You can also | |
10307 | use @value{GDBN} with the UDI-conformant a29k simulator program | |
10308 | @code{ISSTIP}, also available from AMD. | |
10309 | ||
10310 | @table @code | |
10311 | @item target udi @var{keyword} | |
10312 | @kindex udi | |
10313 | Select the UDI interface to a remote a29k board or simulator, where | |
10314 | @var{keyword} is an entry in the AMD configuration file @file{udi_soc}. | |
10315 | This file contains keyword entries which specify parameters used to | |
10316 | connect to a29k targets. If the @file{udi_soc} file is not in your | |
10317 | working directory, you must set the environment variable @samp{UDICONF} | |
10318 | to its pathname. | |
10319 | @end table | |
10320 | ||
6d2ebf8b | 10321 | @node A29K EB29K |
104c1213 JM |
10322 | @subsubsection EBMON protocol for AMD29K |
10323 | ||
10324 | @cindex EB29K board | |
10325 | @cindex running 29K programs | |
10326 | ||
10327 | AMD distributes a 29K development board meant to fit in a PC, together | |
10328 | with a DOS-hosted monitor program called @code{EBMON}. As a shorthand | |
10329 | term, this development system is called the ``EB29K''. To use | |
10330 | @value{GDBN} from a Unix system to run programs on the EB29K board, you | |
10331 | must first connect a serial cable between the PC (which hosts the EB29K | |
10332 | board) and a serial port on the Unix system. In the following, we | |
10333 | assume you've hooked the cable between the PC's @file{COM1} port and | |
10334 | @file{/dev/ttya} on the Unix system. | |
10335 | ||
6d2ebf8b | 10336 | @node Comms (EB29K) |
104c1213 JM |
10337 | @subsubsection Communications setup |
10338 | ||
10339 | The next step is to set up the PC's port, by doing something like this | |
10340 | in DOS on the PC: | |
10341 | ||
10342 | @example | |
10343 | C:\> MODE com1:9600,n,8,1,none | |
10344 | @end example | |
10345 | ||
10346 | @noindent | |
10347 | This example---run on an MS DOS 4.0 system---sets the PC port to 9600 | |
10348 | bps, no parity, eight data bits, one stop bit, and no ``retry'' action; | |
10349 | you must match the communications parameters when establishing the Unix | |
10350 | end of the connection as well. | |
10351 | @c FIXME: Who knows what this "no retry action" crud from the DOS manual may | |
5d161b24 | 10352 | @c mean? It's optional; leave it out? [email protected], 25feb91 |
d4f3574e SS |
10353 | @c |
10354 | @c It's optional, but it's unwise to omit it: who knows what is the | |
10355 | @c default value set when the DOS machines boots? "No retry" means that | |
10356 | @c the DOS serial device driver won't retry the operation if it fails; | |
10357 | @c I understand that this is needed because the GDB serial protocol | |
10358 | @c handles any errors and retransmissions itself. ---Eli Zaretskii, 3sep99 | |
104c1213 JM |
10359 | |
10360 | To give control of the PC to the Unix side of the serial line, type | |
10361 | the following at the DOS console: | |
10362 | ||
10363 | @example | |
10364 | C:\> CTTY com1 | |
10365 | @end example | |
10366 | ||
10367 | @noindent | |
10368 | (Later, if you wish to return control to the DOS console, you can use | |
10369 | the command @code{CTTY con}---but you must send it over the device that | |
96a2c332 | 10370 | had control, in our example over the @file{COM1} serial line.) |
104c1213 JM |
10371 | |
10372 | From the Unix host, use a communications program such as @code{tip} or | |
10373 | @code{cu} to communicate with the PC; for example, | |
10374 | ||
10375 | @example | |
10376 | cu -s 9600 -l /dev/ttya | |
10377 | @end example | |
10378 | ||
10379 | @noindent | |
10380 | The @code{cu} options shown specify, respectively, the linespeed and the | |
10381 | serial port to use. If you use @code{tip} instead, your command line | |
10382 | may look something like the following: | |
10383 | ||
10384 | @example | |
10385 | tip -9600 /dev/ttya | |
10386 | @end example | |
10387 | ||
10388 | @noindent | |
10389 | Your system may require a different name where we show | |
10390 | @file{/dev/ttya} as the argument to @code{tip}. The communications | |
10391 | parameters, including which port to use, are associated with the | |
10392 | @code{tip} argument in the ``remote'' descriptions file---normally the | |
10393 | system table @file{/etc/remote}. | |
10394 | @c FIXME: What if anything needs doing to match the "n,8,1,none" part of | |
10395 | @c the DOS side's comms setup? cu can support -o (odd | |
10396 | @c parity), -e (even parity)---apparently no settings for no parity or | |
10397 | @c for character size. Taken from stty maybe...? John points out tip | |
10398 | @c can set these as internal variables, eg ~s parity=none; man stty | |
10399 | @c suggests that it *might* work to stty these options with stdin or | |
10400 | @c stdout redirected... [email protected], 25feb91 | |
d4f3574e SS |
10401 | @c |
10402 | @c There's nothing to be done for the "none" part of the DOS MODE | |
10403 | @c command. The rest of the parameters should be matched by the | |
10404 | @c baudrate, bits, and parity used by the Unix side. ---Eli Zaretskii, 3Sep99 | |
104c1213 JM |
10405 | |
10406 | @kindex EBMON | |
10407 | Using the @code{tip} or @code{cu} connection, change the DOS working | |
10408 | directory to the directory containing a copy of your 29K program, then | |
10409 | start the PC program @code{EBMON} (an EB29K control program supplied | |
10410 | with your board by AMD). You should see an initial display from | |
10411 | @code{EBMON} similar to the one that follows, ending with the | |
10412 | @code{EBMON} prompt @samp{#}--- | |
10413 | ||
10414 | @example | |
10415 | C:\> G: | |
10416 | ||
10417 | G:\> CD \usr\joe\work29k | |
10418 | ||
10419 | G:\USR\JOE\WORK29K> EBMON | |
10420 | Am29000 PC Coprocessor Board Monitor, version 3.0-18 | |
10421 | Copyright 1990 Advanced Micro Devices, Inc. | |
10422 | Written by Gibbons and Associates, Inc. | |
10423 | ||
10424 | Enter '?' or 'H' for help | |
10425 | ||
10426 | PC Coprocessor Type = EB29K | |
10427 | I/O Base = 0x208 | |
10428 | Memory Base = 0xd0000 | |
10429 | ||
10430 | Data Memory Size = 2048KB | |
10431 | Available I-RAM Range = 0x8000 to 0x1fffff | |
10432 | Available D-RAM Range = 0x80002000 to 0x801fffff | |
10433 | ||
10434 | PageSize = 0x400 | |
10435 | Register Stack Size = 0x800 | |
10436 | Memory Stack Size = 0x1800 | |
10437 | ||
10438 | CPU PRL = 0x3 | |
10439 | Am29027 Available = No | |
10440 | Byte Write Available = Yes | |
10441 | ||
10442 | # ~. | |
10443 | @end example | |
10444 | ||
10445 | Then exit the @code{cu} or @code{tip} program (done in the example by | |
10446 | typing @code{~.} at the @code{EBMON} prompt). @code{EBMON} keeps | |
10447 | running, ready for @value{GDBN} to take over. | |
10448 | ||
10449 | For this example, we've assumed what is probably the most convenient | |
10450 | way to make sure the same 29K program is on both the PC and the Unix | |
d4f3574e | 10451 | system: a PC/NFS connection that establishes ``drive @file{G:}'' on the |
104c1213 JM |
10452 | PC as a file system on the Unix host. If you do not have PC/NFS or |
10453 | something similar connecting the two systems, you must arrange some | |
10454 | other way---perhaps floppy-disk transfer---of getting the 29K program | |
10455 | from the Unix system to the PC; @value{GDBN} does @emph{not} download it over the | |
10456 | serial line. | |
10457 | ||
6d2ebf8b | 10458 | @node gdb-EB29K |
104c1213 JM |
10459 | @subsubsection EB29K cross-debugging |
10460 | ||
10461 | Finally, @code{cd} to the directory containing an image of your 29K | |
10462 | program on the Unix system, and start @value{GDBN}---specifying as argument the | |
10463 | name of your 29K program: | |
10464 | ||
10465 | @example | |
10466 | cd /usr/joe/work29k | |
10467 | @value{GDBP} myfoo | |
10468 | @end example | |
10469 | ||
10470 | @need 500 | |
10471 | Now you can use the @code{target} command: | |
10472 | ||
10473 | @example | |
10474 | target amd-eb /dev/ttya 9600 MYFOO | |
10475 | @c FIXME: test above 'target amd-eb' as spelled, with caps! caps are meant to | |
10476 | @c emphasize that this is the name as seen by DOS (since I think DOS is | |
10477 | @c single-minded about case of letters). [email protected], 25feb91 | |
10478 | @end example | |
10479 | ||
10480 | @noindent | |
10481 | In this example, we've assumed your program is in a file called | |
10482 | @file{myfoo}. Note that the filename given as the last argument to | |
10483 | @code{target amd-eb} should be the name of the program as it appears to DOS. | |
10484 | In our example this is simply @code{MYFOO}, but in general it can include | |
10485 | a DOS path, and depending on your transfer mechanism may not resemble | |
10486 | the name on the Unix side. | |
10487 | ||
10488 | At this point, you can set any breakpoints you wish; when you are ready | |
10489 | to see your program run on the 29K board, use the @value{GDBN} command | |
10490 | @code{run}. | |
10491 | ||
10492 | To stop debugging the remote program, use the @value{GDBN} @code{detach} | |
10493 | command. | |
10494 | ||
10495 | To return control of the PC to its console, use @code{tip} or @code{cu} | |
10496 | once again, after your @value{GDBN} session has concluded, to attach to | |
10497 | @code{EBMON}. You can then type the command @code{q} to shut down | |
10498 | @code{EBMON}, returning control to the DOS command-line interpreter. | |
d4f3574e | 10499 | Type @kbd{CTTY con} to return command input to the main DOS console, |
104c1213 JM |
10500 | and type @kbd{~.} to leave @code{tip} or @code{cu}. |
10501 | ||
6d2ebf8b | 10502 | @node Remote Log |
104c1213 | 10503 | @subsubsection Remote log |
41afff9a | 10504 | @cindex @file{eb.log}, a log file for EB29K |
104c1213 JM |
10505 | @cindex log file for EB29K |
10506 | ||
10507 | The @code{target amd-eb} command creates a file @file{eb.log} in the | |
10508 | current working directory, to help debug problems with the connection. | |
10509 | @file{eb.log} records all the output from @code{EBMON}, including echoes | |
10510 | of the commands sent to it. Running @samp{tail -f} on this file in | |
10511 | another window often helps to understand trouble with @code{EBMON}, or | |
10512 | unexpected events on the PC side of the connection. | |
10513 | ||
6d2ebf8b | 10514 | @node ARM |
104c1213 JM |
10515 | @subsection ARM |
10516 | ||
10517 | @table @code | |
10518 | ||
10519 | @kindex target rdi | |
10520 | @item target rdi @var{dev} | |
10521 | ARM Angel monitor, via RDI library interface to ADP protocol. You may | |
10522 | use this target to communicate with both boards running the Angel | |
10523 | monitor, or with the EmbeddedICE JTAG debug device. | |
5d161b24 | 10524 | |
104c1213 JM |
10525 | @kindex target rdp |
10526 | @item target rdp @var{dev} | |
10527 | ARM Demon monitor. | |
10528 | ||
10529 | @end table | |
10530 | ||
6d2ebf8b | 10531 | @node H8/300 |
104c1213 JM |
10532 | @subsection Hitachi H8/300 |
10533 | ||
10534 | @table @code | |
10535 | ||
d4f3574e | 10536 | @kindex target hms@r{, with H8/300} |
104c1213 JM |
10537 | @item target hms @var{dev} |
10538 | A Hitachi SH, H8/300, or H8/500 board, attached via serial line to your host. | |
10539 | Use special commands @code{device} and @code{speed} to control the serial | |
10540 | line and the communications speed used. | |
10541 | ||
d4f3574e | 10542 | @kindex target e7000@r{, with H8/300} |
104c1213 JM |
10543 | @item target e7000 @var{dev} |
10544 | E7000 emulator for Hitachi H8 and SH. | |
10545 | ||
d4f3574e SS |
10546 | @kindex target sh3@r{, with H8/300} |
10547 | @kindex target sh3e@r{, with H8/300} | |
104c1213 | 10548 | @item target sh3 @var{dev} |
96a2c332 | 10549 | @itemx target sh3e @var{dev} |
104c1213 JM |
10550 | Hitachi SH-3 and SH-3E target systems. |
10551 | ||
10552 | @end table | |
10553 | ||
10554 | @cindex download to H8/300 or H8/500 | |
10555 | @cindex H8/300 or H8/500 download | |
10556 | @cindex download to Hitachi SH | |
10557 | @cindex Hitachi SH download | |
10558 | When you select remote debugging to a Hitachi SH, H8/300, or H8/500 | |
10559 | board, the @code{load} command downloads your program to the Hitachi | |
10560 | board and also opens it as the current executable target for | |
10561 | @value{GDBN} on your host (like the @code{file} command). | |
10562 | ||
10563 | @value{GDBN} needs to know these things to talk to your | |
5d161b24 | 10564 | Hitachi SH, H8/300, or H8/500: |
104c1213 JM |
10565 | |
10566 | @enumerate | |
10567 | @item | |
10568 | that you want to use @samp{target hms}, the remote debugging interface | |
10569 | for Hitachi microprocessors, or @samp{target e7000}, the in-circuit | |
10570 | emulator for the Hitachi SH and the Hitachi 300H. (@samp{target hms} is | |
2df3850c | 10571 | the default when @value{GDBN} is configured specifically for the Hitachi SH, |
104c1213 JM |
10572 | H8/300, or H8/500.) |
10573 | ||
10574 | @item | |
10575 | what serial device connects your host to your Hitachi board (the first | |
10576 | serial device available on your host is the default). | |
10577 | ||
10578 | @item | |
10579 | what speed to use over the serial device. | |
10580 | @end enumerate | |
10581 | ||
10582 | @menu | |
10583 | * Hitachi Boards:: Connecting to Hitachi boards. | |
10584 | * Hitachi ICE:: Using the E7000 In-Circuit Emulator. | |
10585 | * Hitachi Special:: Special @value{GDBN} commands for Hitachi micros. | |
10586 | @end menu | |
10587 | ||
6d2ebf8b | 10588 | @node Hitachi Boards |
104c1213 JM |
10589 | @subsubsection Connecting to Hitachi boards |
10590 | ||
10591 | @c only for Unix hosts | |
10592 | @kindex device | |
10593 | @cindex serial device, Hitachi micros | |
96a2c332 | 10594 | Use the special @code{@value{GDBN}} command @samp{device @var{port}} if you |
104c1213 JM |
10595 | need to explicitly set the serial device. The default @var{port} is the |
10596 | first available port on your host. This is only necessary on Unix | |
10597 | hosts, where it is typically something like @file{/dev/ttya}. | |
10598 | ||
10599 | @kindex speed | |
10600 | @cindex serial line speed, Hitachi micros | |
96a2c332 | 10601 | @code{@value{GDBN}} has another special command to set the communications |
104c1213 | 10602 | speed: @samp{speed @var{bps}}. This command also is only used from Unix |
2df3850c | 10603 | hosts; on DOS hosts, set the line speed as usual from outside @value{GDBN} with |
d4f3574e SS |
10604 | the DOS @code{mode} command (for instance, |
10605 | @w{@kbd{mode com2:9600,n,8,1,p}} for a 9600@dmn{bps} connection). | |
104c1213 JM |
10606 | |
10607 | The @samp{device} and @samp{speed} commands are available only when you | |
10608 | use a Unix host to debug your Hitachi microprocessor programs. If you | |
10609 | use a DOS host, | |
10610 | @value{GDBN} depends on an auxiliary terminate-and-stay-resident program | |
10611 | called @code{asynctsr} to communicate with the development board | |
10612 | through a PC serial port. You must also use the DOS @code{mode} command | |
10613 | to set up the serial port on the DOS side. | |
10614 | ||
10615 | The following sample session illustrates the steps needed to start a | |
10616 | program under @value{GDBN} control on an H8/300. The example uses a | |
10617 | sample H8/300 program called @file{t.x}. The procedure is the same for | |
10618 | the Hitachi SH and the H8/500. | |
10619 | ||
10620 | First hook up your development board. In this example, we use a | |
10621 | board attached to serial port @code{COM2}; if you use a different serial | |
10622 | port, substitute its name in the argument of the @code{mode} command. | |
10623 | When you call @code{asynctsr}, the auxiliary comms program used by the | |
d4f3574e | 10624 | debugger, you give it just the numeric part of the serial port's name; |
104c1213 JM |
10625 | for example, @samp{asyncstr 2} below runs @code{asyncstr} on |
10626 | @code{COM2}. | |
10627 | ||
10628 | @example | |
10629 | C:\H8300\TEST> asynctsr 2 | |
10630 | C:\H8300\TEST> mode com2:9600,n,8,1,p | |
10631 | ||
10632 | Resident portion of MODE loaded | |
10633 | ||
10634 | COM2: 9600, n, 8, 1, p | |
10635 | ||
10636 | @end example | |
10637 | ||
10638 | @quotation | |
10639 | @emph{Warning:} We have noticed a bug in PC-NFS that conflicts with | |
10640 | @code{asynctsr}. If you also run PC-NFS on your DOS host, you may need to | |
10641 | disable it, or even boot without it, to use @code{asynctsr} to control | |
10642 | your development board. | |
10643 | @end quotation | |
10644 | ||
d4f3574e | 10645 | @kindex target hms@r{, and serial protocol} |
104c1213 JM |
10646 | Now that serial communications are set up, and the development board is |
10647 | connected, you can start up @value{GDBN}. Call @code{@value{GDBP}} with | |
96a2c332 | 10648 | the name of your program as the argument. @code{@value{GDBN}} prompts |
104c1213 JM |
10649 | you, as usual, with the prompt @samp{(@value{GDBP})}. Use two special |
10650 | commands to begin your debugging session: @samp{target hms} to specify | |
10651 | cross-debugging to the Hitachi board, and the @code{load} command to | |
10652 | download your program to the board. @code{load} displays the names of | |
10653 | the program's sections, and a @samp{*} for each 2K of data downloaded. | |
10654 | (If you want to refresh @value{GDBN} data on symbols or on the | |
10655 | executable file without downloading, use the @value{GDBN} commands | |
10656 | @code{file} or @code{symbol-file}. These commands, and @code{load} | |
10657 | itself, are described in @ref{Files,,Commands to specify files}.) | |
10658 | ||
10659 | @smallexample | |
10660 | (eg-C:\H8300\TEST) @value{GDBP} t.x | |
2df3850c | 10661 | @value{GDBN} is free software and you are welcome to distribute copies |
5d161b24 | 10662 | of it under certain conditions; type "show copying" to see |
104c1213 | 10663 | the conditions. |
5d161b24 | 10664 | There is absolutely no warranty for @value{GDBN}; type "show warranty" |
104c1213 | 10665 | for details. |
2df3850c JM |
10666 | @value{GDBN} @value{GDBVN}, Copyright 1992 Free Software Foundation, Inc... |
10667 | (@value{GDBP}) target hms | |
104c1213 | 10668 | Connected to remote H8/300 HMS system. |
2df3850c | 10669 | (@value{GDBP}) load t.x |
104c1213 JM |
10670 | .text : 0x8000 .. 0xabde *********** |
10671 | .data : 0xabde .. 0xad30 * | |
10672 | .stack : 0xf000 .. 0xf014 * | |
10673 | @end smallexample | |
10674 | ||
10675 | At this point, you're ready to run or debug your program. From here on, | |
10676 | you can use all the usual @value{GDBN} commands. The @code{break} command | |
10677 | sets breakpoints; the @code{run} command starts your program; | |
10678 | @code{print} or @code{x} display data; the @code{continue} command | |
10679 | resumes execution after stopping at a breakpoint. You can use the | |
10680 | @code{help} command at any time to find out more about @value{GDBN} commands. | |
10681 | ||
10682 | Remember, however, that @emph{operating system} facilities aren't | |
10683 | available on your development board; for example, if your program hangs, | |
10684 | you can't send an interrupt---but you can press the @sc{reset} switch! | |
10685 | ||
10686 | Use the @sc{reset} button on the development board | |
10687 | @itemize @bullet | |
10688 | @item | |
10689 | to interrupt your program (don't use @kbd{ctl-C} on the DOS host---it has | |
10690 | no way to pass an interrupt signal to the development board); and | |
10691 | ||
10692 | @item | |
10693 | to return to the @value{GDBN} command prompt after your program finishes | |
10694 | normally. The communications protocol provides no other way for @value{GDBN} | |
10695 | to detect program completion. | |
10696 | @end itemize | |
10697 | ||
10698 | In either case, @value{GDBN} sees the effect of a @sc{reset} on the | |
10699 | development board as a ``normal exit'' of your program. | |
10700 | ||
6d2ebf8b | 10701 | @node Hitachi ICE |
104c1213 JM |
10702 | @subsubsection Using the E7000 in-circuit emulator |
10703 | ||
d4f3574e | 10704 | @kindex target e7000@r{, with Hitachi ICE} |
104c1213 JM |
10705 | You can use the E7000 in-circuit emulator to develop code for either the |
10706 | Hitachi SH or the H8/300H. Use one of these forms of the @samp{target | |
10707 | e7000} command to connect @value{GDBN} to your E7000: | |
10708 | ||
10709 | @table @code | |
10710 | @item target e7000 @var{port} @var{speed} | |
10711 | Use this form if your E7000 is connected to a serial port. The | |
10712 | @var{port} argument identifies what serial port to use (for example, | |
10713 | @samp{com2}). The third argument is the line speed in bits per second | |
10714 | (for example, @samp{9600}). | |
10715 | ||
10716 | @item target e7000 @var{hostname} | |
10717 | If your E7000 is installed as a host on a TCP/IP network, you can just | |
10718 | specify its hostname; @value{GDBN} uses @code{telnet} to connect. | |
10719 | @end table | |
10720 | ||
6d2ebf8b | 10721 | @node Hitachi Special |
104c1213 JM |
10722 | @subsubsection Special @value{GDBN} commands for Hitachi micros |
10723 | ||
10724 | Some @value{GDBN} commands are available only for the H8/300: | |
10725 | ||
10726 | @table @code | |
10727 | ||
10728 | @kindex set machine | |
10729 | @kindex show machine | |
10730 | @item set machine h8300 | |
10731 | @itemx set machine h8300h | |
10732 | Condition @value{GDBN} for one of the two variants of the H8/300 | |
10733 | architecture with @samp{set machine}. You can use @samp{show machine} | |
10734 | to check which variant is currently in effect. | |
10735 | ||
10736 | @end table | |
10737 | ||
6d2ebf8b | 10738 | @node H8/500 |
104c1213 JM |
10739 | @subsection H8/500 |
10740 | ||
10741 | @table @code | |
10742 | ||
10743 | @kindex set memory @var{mod} | |
10744 | @cindex memory models, H8/500 | |
10745 | @item set memory @var{mod} | |
10746 | @itemx show memory | |
10747 | Specify which H8/500 memory model (@var{mod}) you are using with | |
10748 | @samp{set memory}; check which memory model is in effect with @samp{show | |
10749 | memory}. The accepted values for @var{mod} are @code{small}, | |
10750 | @code{big}, @code{medium}, and @code{compact}. | |
10751 | ||
10752 | @end table | |
10753 | ||
6d2ebf8b | 10754 | @node i960 |
104c1213 JM |
10755 | @subsection Intel i960 |
10756 | ||
10757 | @table @code | |
10758 | ||
10759 | @kindex target mon960 | |
10760 | @item target mon960 @var{dev} | |
10761 | MON960 monitor for Intel i960. | |
10762 | ||
f0ca3dce | 10763 | @kindex target nindy |
104c1213 JM |
10764 | @item target nindy @var{devicename} |
10765 | An Intel 960 board controlled by a Nindy Monitor. @var{devicename} is | |
10766 | the name of the serial device to use for the connection, e.g. | |
10767 | @file{/dev/ttya}. | |
10768 | ||
10769 | @end table | |
10770 | ||
10771 | @cindex Nindy | |
10772 | @cindex i960 | |
10773 | @dfn{Nindy} is a ROM Monitor program for Intel 960 target systems. When | |
10774 | @value{GDBN} is configured to control a remote Intel 960 using Nindy, you can | |
10775 | tell @value{GDBN} how to connect to the 960 in several ways: | |
10776 | ||
10777 | @itemize @bullet | |
10778 | @item | |
10779 | Through command line options specifying serial port, version of the | |
10780 | Nindy protocol, and communications speed; | |
10781 | ||
10782 | @item | |
10783 | By responding to a prompt on startup; | |
10784 | ||
10785 | @item | |
10786 | By using the @code{target} command at any point during your @value{GDBN} | |
10787 | session. @xref{Target Commands, ,Commands for managing targets}. | |
10788 | ||
104c1213 JM |
10789 | @end itemize |
10790 | ||
10791 | @cindex download to Nindy-960 | |
10792 | With the Nindy interface to an Intel 960 board, @code{load} | |
10793 | downloads @var{filename} to the 960 as well as adding its symbols in | |
10794 | @value{GDBN}. | |
10795 | ||
10796 | @menu | |
10797 | * Nindy Startup:: Startup with Nindy | |
10798 | * Nindy Options:: Options for Nindy | |
10799 | * Nindy Reset:: Nindy reset command | |
10800 | @end menu | |
10801 | ||
6d2ebf8b | 10802 | @node Nindy Startup |
104c1213 JM |
10803 | @subsubsection Startup with Nindy |
10804 | ||
10805 | If you simply start @code{@value{GDBP}} without using any command-line | |
10806 | options, you are prompted for what serial port to use, @emph{before} you | |
10807 | reach the ordinary @value{GDBN} prompt: | |
10808 | ||
10809 | @example | |
5d161b24 | 10810 | Attach /dev/ttyNN -- specify NN, or "quit" to quit: |
104c1213 JM |
10811 | @end example |
10812 | ||
10813 | @noindent | |
10814 | Respond to the prompt with whatever suffix (after @samp{/dev/tty}) | |
10815 | identifies the serial port you want to use. You can, if you choose, | |
10816 | simply start up with no Nindy connection by responding to the prompt | |
10817 | with an empty line. If you do this and later wish to attach to Nindy, | |
10818 | use @code{target} (@pxref{Target Commands, ,Commands for managing targets}). | |
10819 | ||
6d2ebf8b | 10820 | @node Nindy Options |
104c1213 JM |
10821 | @subsubsection Options for Nindy |
10822 | ||
10823 | These are the startup options for beginning your @value{GDBN} session with a | |
10824 | Nindy-960 board attached: | |
10825 | ||
10826 | @table @code | |
10827 | @item -r @var{port} | |
10828 | Specify the serial port name of a serial interface to be used to connect | |
10829 | to the target system. This option is only available when @value{GDBN} is | |
10830 | configured for the Intel 960 target architecture. You may specify | |
10831 | @var{port} as any of: a full pathname (e.g. @samp{-r /dev/ttya}), a | |
10832 | device name in @file{/dev} (e.g. @samp{-r ttya}), or simply the unique | |
10833 | suffix for a specific @code{tty} (e.g. @samp{-r a}). | |
10834 | ||
10835 | @item -O | |
10836 | (An uppercase letter ``O'', not a zero.) Specify that @value{GDBN} should use | |
10837 | the ``old'' Nindy monitor protocol to connect to the target system. | |
10838 | This option is only available when @value{GDBN} is configured for the Intel 960 | |
10839 | target architecture. | |
10840 | ||
10841 | @quotation | |
10842 | @emph{Warning:} if you specify @samp{-O}, but are actually trying to | |
10843 | connect to a target system that expects the newer protocol, the connection | |
10844 | fails, appearing to be a speed mismatch. @value{GDBN} repeatedly | |
10845 | attempts to reconnect at several different line speeds. You can abort | |
10846 | this process with an interrupt. | |
10847 | @end quotation | |
10848 | ||
10849 | @item -brk | |
10850 | Specify that @value{GDBN} should first send a @code{BREAK} signal to the target | |
10851 | system, in an attempt to reset it, before connecting to a Nindy target. | |
10852 | ||
10853 | @quotation | |
10854 | @emph{Warning:} Many target systems do not have the hardware that this | |
10855 | requires; it only works with a few boards. | |
10856 | @end quotation | |
10857 | @end table | |
10858 | ||
10859 | The standard @samp{-b} option controls the line speed used on the serial | |
10860 | port. | |
10861 | ||
10862 | @c @group | |
6d2ebf8b | 10863 | @node Nindy Reset |
104c1213 JM |
10864 | @subsubsection Nindy reset command |
10865 | ||
10866 | @table @code | |
10867 | @item reset | |
10868 | @kindex reset | |
10869 | For a Nindy target, this command sends a ``break'' to the remote target | |
10870 | system; this is only useful if the target has been equipped with a | |
10871 | circuit to perform a hard reset (or some other interesting action) when | |
10872 | a break is detected. | |
10873 | @end table | |
10874 | @c @end group | |
10875 | ||
6d2ebf8b | 10876 | @node M32R/D |
104c1213 JM |
10877 | @subsection Mitsubishi M32R/D |
10878 | ||
10879 | @table @code | |
10880 | ||
10881 | @kindex target m32r | |
10882 | @item target m32r @var{dev} | |
10883 | Mitsubishi M32R/D ROM monitor. | |
10884 | ||
10885 | @end table | |
10886 | ||
6d2ebf8b | 10887 | @node M68K |
104c1213 JM |
10888 | @subsection M68k |
10889 | ||
10890 | The Motorola m68k configuration includes ColdFire support, and | |
10891 | target command for the following ROM monitors. | |
10892 | ||
10893 | @table @code | |
10894 | ||
10895 | @kindex target abug | |
10896 | @item target abug @var{dev} | |
10897 | ABug ROM monitor for M68K. | |
10898 | ||
10899 | @kindex target cpu32bug | |
10900 | @item target cpu32bug @var{dev} | |
10901 | CPU32BUG monitor, running on a CPU32 (M68K) board. | |
10902 | ||
10903 | @kindex target dbug | |
10904 | @item target dbug @var{dev} | |
10905 | dBUG ROM monitor for Motorola ColdFire. | |
10906 | ||
10907 | @kindex target est | |
10908 | @item target est @var{dev} | |
10909 | EST-300 ICE monitor, running on a CPU32 (M68K) board. | |
10910 | ||
10911 | @kindex target rom68k | |
10912 | @item target rom68k @var{dev} | |
10913 | ROM 68K monitor, running on an M68K IDP board. | |
10914 | ||
10915 | @end table | |
10916 | ||
10917 | If @value{GDBN} is configured with @code{m68*-ericsson-*}, it will | |
10918 | instead have only a single special target command: | |
10919 | ||
10920 | @table @code | |
10921 | ||
10922 | @kindex target es1800 | |
10923 | @item target es1800 @var{dev} | |
10924 | ES-1800 emulator for M68K. | |
10925 | ||
10926 | @end table | |
10927 | ||
10928 | [context?] | |
10929 | ||
10930 | @table @code | |
10931 | ||
10932 | @kindex target rombug | |
10933 | @item target rombug @var{dev} | |
10934 | ROMBUG ROM monitor for OS/9000. | |
10935 | ||
10936 | @end table | |
10937 | ||
6d2ebf8b | 10938 | @node M88K |
104c1213 JM |
10939 | @subsection M88K |
10940 | ||
10941 | @table @code | |
10942 | ||
10943 | @kindex target bug | |
10944 | @item target bug @var{dev} | |
10945 | BUG monitor, running on a MVME187 (m88k) board. | |
10946 | ||
10947 | @end table | |
10948 | ||
6d2ebf8b | 10949 | @node MIPS Embedded |
104c1213 JM |
10950 | @subsection MIPS Embedded |
10951 | ||
10952 | @cindex MIPS boards | |
10953 | @value{GDBN} can use the MIPS remote debugging protocol to talk to a | |
10954 | MIPS board attached to a serial line. This is available when | |
10955 | you configure @value{GDBN} with @samp{--target=mips-idt-ecoff}. | |
10956 | ||
10957 | @need 1000 | |
10958 | Use these @value{GDBN} commands to specify the connection to your target board: | |
10959 | ||
10960 | @table @code | |
10961 | @item target mips @var{port} | |
10962 | @kindex target mips @var{port} | |
10963 | To run a program on the board, start up @code{@value{GDBP}} with the | |
10964 | name of your program as the argument. To connect to the board, use the | |
10965 | command @samp{target mips @var{port}}, where @var{port} is the name of | |
10966 | the serial port connected to the board. If the program has not already | |
10967 | been downloaded to the board, you may use the @code{load} command to | |
10968 | download it. You can then use all the usual @value{GDBN} commands. | |
10969 | ||
10970 | For example, this sequence connects to the target board through a serial | |
10971 | port, and loads and runs a program called @var{prog} through the | |
10972 | debugger: | |
10973 | ||
10974 | @example | |
10975 | host$ @value{GDBP} @var{prog} | |
2df3850c JM |
10976 | @value{GDBN} is free software and @dots{} |
10977 | (@value{GDBP}) target mips /dev/ttyb | |
10978 | (@value{GDBP}) load @var{prog} | |
10979 | (@value{GDBP}) run | |
104c1213 JM |
10980 | @end example |
10981 | ||
10982 | @item target mips @var{hostname}:@var{portnumber} | |
10983 | On some @value{GDBN} host configurations, you can specify a TCP | |
10984 | connection (for instance, to a serial line managed by a terminal | |
10985 | concentrator) instead of a serial port, using the syntax | |
10986 | @samp{@var{hostname}:@var{portnumber}}. | |
10987 | ||
10988 | @item target pmon @var{port} | |
10989 | @kindex target pmon @var{port} | |
10990 | PMON ROM monitor. | |
10991 | ||
10992 | @item target ddb @var{port} | |
10993 | @kindex target ddb @var{port} | |
10994 | NEC's DDB variant of PMON for Vr4300. | |
10995 | ||
10996 | @item target lsi @var{port} | |
10997 | @kindex target lsi @var{port} | |
10998 | LSI variant of PMON. | |
10999 | ||
11000 | @kindex target r3900 | |
11001 | @item target r3900 @var{dev} | |
11002 | Densan DVE-R3900 ROM monitor for Toshiba R3900 Mips. | |
11003 | ||
11004 | @kindex target array | |
11005 | @item target array @var{dev} | |
11006 | Array Tech LSI33K RAID controller board. | |
11007 | ||
11008 | @end table | |
11009 | ||
11010 | ||
11011 | @noindent | |
11012 | @value{GDBN} also supports these special commands for MIPS targets: | |
11013 | ||
11014 | @table @code | |
11015 | @item set processor @var{args} | |
11016 | @itemx show processor | |
11017 | @kindex set processor @var{args} | |
11018 | @kindex show processor | |
11019 | Use the @code{set processor} command to set the type of MIPS | |
11020 | processor when you want to access processor-type-specific registers. | |
5d161b24 | 11021 | For example, @code{set processor @var{r3041}} tells @value{GDBN} |
96c405b3 | 11022 | to use the CPU registers appropriate for the 3041 chip. |
5d161b24 | 11023 | Use the @code{show processor} command to see what MIPS processor @value{GDBN} |
104c1213 | 11024 | is using. Use the @code{info reg} command to see what registers |
5d161b24 | 11025 | @value{GDBN} is using. |
104c1213 JM |
11026 | |
11027 | @item set mipsfpu double | |
11028 | @itemx set mipsfpu single | |
11029 | @itemx set mipsfpu none | |
11030 | @itemx show mipsfpu | |
11031 | @kindex set mipsfpu | |
11032 | @kindex show mipsfpu | |
11033 | @cindex MIPS remote floating point | |
11034 | @cindex floating point, MIPS remote | |
11035 | If your target board does not support the MIPS floating point | |
11036 | coprocessor, you should use the command @samp{set mipsfpu none} (if you | |
96a2c332 | 11037 | need this, you may wish to put the command in your @value{GDBN} init |
104c1213 JM |
11038 | file). This tells @value{GDBN} how to find the return value of |
11039 | functions which return floating point values. It also allows | |
11040 | @value{GDBN} to avoid saving the floating point registers when calling | |
11041 | functions on the board. If you are using a floating point coprocessor | |
11042 | with only single precision floating point support, as on the @sc{r4650} | |
11043 | processor, use the command @samp{set mipsfpu single}. The default | |
11044 | double precision floating point coprocessor may be selected using | |
11045 | @samp{set mipsfpu double}. | |
11046 | ||
11047 | In previous versions the only choices were double precision or no | |
11048 | floating point, so @samp{set mipsfpu on} will select double precision | |
11049 | and @samp{set mipsfpu off} will select no floating point. | |
11050 | ||
11051 | As usual, you can inquire about the @code{mipsfpu} variable with | |
11052 | @samp{show mipsfpu}. | |
11053 | ||
11054 | @item set remotedebug @var{n} | |
11055 | @itemx show remotedebug | |
d4f3574e SS |
11056 | @kindex set remotedebug@r{, MIPS protocol} |
11057 | @kindex show remotedebug@r{, MIPS protocol} | |
104c1213 JM |
11058 | @cindex @code{remotedebug}, MIPS protocol |
11059 | @cindex MIPS @code{remotedebug} protocol | |
11060 | @c FIXME! For this to be useful, you must know something about the MIPS | |
11061 | @c FIXME...protocol. Where is it described? | |
11062 | You can see some debugging information about communications with the board | |
11063 | by setting the @code{remotedebug} variable. If you set it to @code{1} using | |
11064 | @samp{set remotedebug 1}, every packet is displayed. If you set it | |
11065 | to @code{2}, every character is displayed. You can check the current value | |
11066 | at any time with the command @samp{show remotedebug}. | |
11067 | ||
11068 | @item set timeout @var{seconds} | |
11069 | @itemx set retransmit-timeout @var{seconds} | |
11070 | @itemx show timeout | |
11071 | @itemx show retransmit-timeout | |
11072 | @cindex @code{timeout}, MIPS protocol | |
11073 | @cindex @code{retransmit-timeout}, MIPS protocol | |
11074 | @kindex set timeout | |
11075 | @kindex show timeout | |
11076 | @kindex set retransmit-timeout | |
11077 | @kindex show retransmit-timeout | |
11078 | You can control the timeout used while waiting for a packet, in the MIPS | |
11079 | remote protocol, with the @code{set timeout @var{seconds}} command. The | |
11080 | default is 5 seconds. Similarly, you can control the timeout used while | |
11081 | waiting for an acknowledgement of a packet with the @code{set | |
11082 | retransmit-timeout @var{seconds}} command. The default is 3 seconds. | |
11083 | You can inspect both values with @code{show timeout} and @code{show | |
11084 | retransmit-timeout}. (These commands are @emph{only} available when | |
11085 | @value{GDBN} is configured for @samp{--target=mips-idt-ecoff}.) | |
11086 | ||
11087 | The timeout set by @code{set timeout} does not apply when @value{GDBN} | |
11088 | is waiting for your program to stop. In that case, @value{GDBN} waits | |
11089 | forever because it has no way of knowing how long the program is going | |
11090 | to run before stopping. | |
11091 | @end table | |
11092 | ||
6d2ebf8b | 11093 | @node PowerPC |
104c1213 JM |
11094 | @subsection PowerPC |
11095 | ||
11096 | @table @code | |
11097 | ||
11098 | @kindex target dink32 | |
11099 | @item target dink32 @var{dev} | |
11100 | DINK32 ROM monitor. | |
11101 | ||
11102 | @kindex target ppcbug | |
11103 | @item target ppcbug @var{dev} | |
11104 | @kindex target ppcbug1 | |
11105 | @item target ppcbug1 @var{dev} | |
11106 | PPCBUG ROM monitor for PowerPC. | |
11107 | ||
11108 | @kindex target sds | |
11109 | @item target sds @var{dev} | |
11110 | SDS monitor, running on a PowerPC board (such as Motorola's ADS). | |
11111 | ||
11112 | @end table | |
11113 | ||
6d2ebf8b | 11114 | @node PA |
104c1213 JM |
11115 | @subsection HP PA Embedded |
11116 | ||
11117 | @table @code | |
11118 | ||
11119 | @kindex target op50n | |
11120 | @item target op50n @var{dev} | |
11121 | OP50N monitor, running on an OKI HPPA board. | |
11122 | ||
11123 | @kindex target w89k | |
11124 | @item target w89k @var{dev} | |
11125 | W89K monitor, running on a Winbond HPPA board. | |
11126 | ||
11127 | @end table | |
11128 | ||
6d2ebf8b | 11129 | @node SH |
104c1213 JM |
11130 | @subsection Hitachi SH |
11131 | ||
11132 | @table @code | |
11133 | ||
d4f3574e | 11134 | @kindex target hms@r{, with Hitachi SH} |
104c1213 JM |
11135 | @item target hms @var{dev} |
11136 | A Hitachi SH board attached via serial line to your host. Use special | |
11137 | commands @code{device} and @code{speed} to control the serial line and | |
11138 | the communications speed used. | |
11139 | ||
d4f3574e | 11140 | @kindex target e7000@r{, with Hitachi SH} |
104c1213 JM |
11141 | @item target e7000 @var{dev} |
11142 | E7000 emulator for Hitachi SH. | |
11143 | ||
d4f3574e SS |
11144 | @kindex target sh3@r{, with SH} |
11145 | @kindex target sh3e@r{, with SH} | |
104c1213 JM |
11146 | @item target sh3 @var{dev} |
11147 | @item target sh3e @var{dev} | |
11148 | Hitachi SH-3 and SH-3E target systems. | |
11149 | ||
11150 | @end table | |
11151 | ||
6d2ebf8b | 11152 | @node Sparclet |
104c1213 JM |
11153 | @subsection Tsqware Sparclet |
11154 | ||
11155 | @cindex Sparclet | |
11156 | ||
5d161b24 DB |
11157 | @value{GDBN} enables developers to debug tasks running on |
11158 | Sparclet targets from a Unix host. | |
104c1213 JM |
11159 | @value{GDBN} uses code that runs on |
11160 | both the Unix host and on the Sparclet target. The program | |
5d161b24 | 11161 | @code{@value{GDBP}} is installed and executed on the Unix host. |
104c1213 JM |
11162 | |
11163 | @table @code | |
f0ca3dce | 11164 | @item remotetimeout @var{args} |
104c1213 | 11165 | @kindex remotetimeout |
5d161b24 DB |
11166 | @value{GDBN} supports the option @code{remotetimeout}. |
11167 | This option is set by the user, and @var{args} represents the number of | |
11168 | seconds @value{GDBN} waits for responses. | |
104c1213 JM |
11169 | @end table |
11170 | ||
41afff9a | 11171 | @cindex compiling, on Sparclet |
5d161b24 | 11172 | When compiling for debugging, include the options @samp{-g} to get debug |
d4f3574e | 11173 | information and @samp{-Ttext} to relocate the program to where you wish to |
5d161b24 | 11174 | load it on the target. You may also want to add the options @samp{-n} or |
d4f3574e | 11175 | @samp{-N} in order to reduce the size of the sections. Example: |
104c1213 JM |
11176 | |
11177 | @example | |
11178 | sparclet-aout-gcc prog.c -Ttext 0x12010000 -g -o prog -N | |
11179 | @end example | |
11180 | ||
d4f3574e | 11181 | You can use @code{objdump} to verify that the addresses are what you intended: |
104c1213 JM |
11182 | |
11183 | @example | |
11184 | sparclet-aout-objdump --headers --syms prog | |
11185 | @end example | |
11186 | ||
41afff9a | 11187 | @cindex running, on Sparclet |
104c1213 JM |
11188 | Once you have set |
11189 | your Unix execution search path to find @value{GDBN}, you are ready to | |
5d161b24 | 11190 | run @value{GDBN}. From your Unix host, run @code{@value{GDBP}} |
104c1213 JM |
11191 | (or @code{sparclet-aout-gdb}, depending on your installation). |
11192 | ||
11193 | @value{GDBN} comes up showing the prompt: | |
11194 | ||
11195 | @example | |
11196 | (gdbslet) | |
11197 | @end example | |
11198 | ||
11199 | @menu | |
11200 | * Sparclet File:: Setting the file to debug | |
11201 | * Sparclet Connection:: Connecting to Sparclet | |
11202 | * Sparclet Download:: Sparclet download | |
5d161b24 | 11203 | * Sparclet Execution:: Running and debugging |
104c1213 JM |
11204 | @end menu |
11205 | ||
6d2ebf8b | 11206 | @node Sparclet File |
104c1213 JM |
11207 | @subsubsection Setting file to debug |
11208 | ||
11209 | The @value{GDBN} command @code{file} lets you choose with program to debug. | |
11210 | ||
11211 | @example | |
11212 | (gdbslet) file prog | |
11213 | @end example | |
11214 | ||
11215 | @need 1000 | |
11216 | @value{GDBN} then attempts to read the symbol table of @file{prog}. | |
11217 | @value{GDBN} locates | |
11218 | the file by searching the directories listed in the command search | |
11219 | path. | |
11220 | If the file was compiled with debug information (option "-g"), source | |
11221 | files will be searched as well. | |
11222 | @value{GDBN} locates | |
11223 | the source files by searching the directories listed in the directory search | |
11224 | path (@pxref{Environment, ,Your program's environment}). | |
11225 | If it fails | |
11226 | to find a file, it displays a message such as: | |
11227 | ||
11228 | @example | |
11229 | prog: No such file or directory. | |
11230 | @end example | |
11231 | ||
11232 | When this happens, add the appropriate directories to the search paths with | |
5d161b24 | 11233 | the @value{GDBN} commands @code{path} and @code{dir}, and execute the |
104c1213 JM |
11234 | @code{target} command again. |
11235 | ||
6d2ebf8b | 11236 | @node Sparclet Connection |
104c1213 JM |
11237 | @subsubsection Connecting to Sparclet |
11238 | ||
11239 | The @value{GDBN} command @code{target} lets you connect to a Sparclet target. | |
11240 | To connect to a target on serial port ``@code{ttya}'', type: | |
11241 | ||
11242 | @example | |
11243 | (gdbslet) target sparclet /dev/ttya | |
11244 | Remote target sparclet connected to /dev/ttya | |
5d161b24 | 11245 | main () at ../prog.c:3 |
104c1213 JM |
11246 | @end example |
11247 | ||
11248 | @need 750 | |
11249 | @value{GDBN} displays messages like these: | |
11250 | ||
d4f3574e | 11251 | @example |
104c1213 | 11252 | Connected to ttya. |
d4f3574e | 11253 | @end example |
104c1213 | 11254 | |
6d2ebf8b | 11255 | @node Sparclet Download |
104c1213 JM |
11256 | @subsubsection Sparclet download |
11257 | ||
11258 | @cindex download to Sparclet | |
5d161b24 | 11259 | Once connected to the Sparclet target, |
104c1213 JM |
11260 | you can use the @value{GDBN} |
11261 | @code{load} command to download the file from the host to the target. | |
11262 | The file name and load offset should be given as arguments to the @code{load} | |
11263 | command. | |
5d161b24 | 11264 | Since the file format is aout, the program must be loaded to the starting |
d4f3574e | 11265 | address. You can use @code{objdump} to find out what this value is. The load |
104c1213 JM |
11266 | offset is an offset which is added to the VMA (virtual memory address) |
11267 | of each of the file's sections. | |
11268 | For instance, if the program | |
11269 | @file{prog} was linked to text address 0x1201000, with data at 0x12010160 | |
11270 | and bss at 0x12010170, in @value{GDBN}, type: | |
11271 | ||
11272 | @example | |
11273 | (gdbslet) load prog 0x12010000 | |
11274 | Loading section .text, size 0xdb0 vma 0x12010000 | |
11275 | @end example | |
11276 | ||
5d161b24 DB |
11277 | If the code is loaded at a different address then what the program was linked |
11278 | to, you may need to use the @code{section} and @code{add-symbol-file} commands | |
104c1213 JM |
11279 | to tell @value{GDBN} where to map the symbol table. |
11280 | ||
6d2ebf8b | 11281 | @node Sparclet Execution |
104c1213 JM |
11282 | @subsubsection Running and debugging |
11283 | ||
11284 | @cindex running and debugging Sparclet programs | |
11285 | You can now begin debugging the task using @value{GDBN}'s execution control | |
5d161b24 | 11286 | commands, @code{b}, @code{step}, @code{run}, etc. See the @value{GDBN} |
104c1213 JM |
11287 | manual for the list of commands. |
11288 | ||
11289 | @example | |
11290 | (gdbslet) b main | |
11291 | Breakpoint 1 at 0x12010000: file prog.c, line 3. | |
5d161b24 | 11292 | (gdbslet) run |
104c1213 JM |
11293 | Starting program: prog |
11294 | Breakpoint 1, main (argc=1, argv=0xeffff21c) at prog.c:3 | |
11295 | 3 char *symarg = 0; | |
11296 | (gdbslet) step | |
11297 | 4 char *execarg = "hello!"; | |
5d161b24 | 11298 | (gdbslet) |
104c1213 JM |
11299 | @end example |
11300 | ||
6d2ebf8b | 11301 | @node Sparclite |
104c1213 JM |
11302 | @subsection Fujitsu Sparclite |
11303 | ||
11304 | @table @code | |
11305 | ||
11306 | @kindex target sparclite | |
11307 | @item target sparclite @var{dev} | |
5d161b24 DB |
11308 | Fujitsu sparclite boards, used only for the purpose of loading. |
11309 | You must use an additional command to debug the program. | |
11310 | For example: target remote @var{dev} using @value{GDBN} standard | |
104c1213 JM |
11311 | remote protocol. |
11312 | ||
11313 | @end table | |
11314 | ||
6d2ebf8b | 11315 | @node ST2000 |
104c1213 JM |
11316 | @subsection Tandem ST2000 |
11317 | ||
2df3850c | 11318 | @value{GDBN} may be used with a Tandem ST2000 phone switch, running Tandem's |
104c1213 JM |
11319 | STDBUG protocol. |
11320 | ||
11321 | To connect your ST2000 to the host system, see the manufacturer's | |
11322 | manual. Once the ST2000 is physically attached, you can run: | |
11323 | ||
11324 | @example | |
11325 | target st2000 @var{dev} @var{speed} | |
11326 | @end example | |
11327 | ||
11328 | @noindent | |
11329 | to establish it as your debugging environment. @var{dev} is normally | |
11330 | the name of a serial device, such as @file{/dev/ttya}, connected to the | |
11331 | ST2000 via a serial line. You can instead specify @var{dev} as a TCP | |
11332 | connection (for example, to a serial line attached via a terminal | |
11333 | concentrator) using the syntax @code{@var{hostname}:@var{portnumber}}. | |
11334 | ||
11335 | The @code{load} and @code{attach} commands are @emph{not} defined for | |
11336 | this target; you must load your program into the ST2000 as you normally | |
11337 | would for standalone operation. @value{GDBN} reads debugging information | |
11338 | (such as symbols) from a separate, debugging version of the program | |
11339 | available on your host computer. | |
11340 | @c FIXME!! This is terribly vague; what little content is here is | |
11341 | @c basically hearsay. | |
11342 | ||
11343 | @cindex ST2000 auxiliary commands | |
11344 | These auxiliary @value{GDBN} commands are available to help you with the ST2000 | |
11345 | environment: | |
11346 | ||
11347 | @table @code | |
11348 | @item st2000 @var{command} | |
11349 | @kindex st2000 @var{cmd} | |
11350 | @cindex STDBUG commands (ST2000) | |
11351 | @cindex commands to STDBUG (ST2000) | |
11352 | Send a @var{command} to the STDBUG monitor. See the manufacturer's | |
11353 | manual for available commands. | |
11354 | ||
11355 | @item connect | |
11356 | @cindex connect (to STDBUG) | |
11357 | Connect the controlling terminal to the STDBUG command monitor. When | |
11358 | you are done interacting with STDBUG, typing either of two character | |
11359 | sequences gets you back to the @value{GDBN} command prompt: | |
11360 | @kbd{@key{RET}~.} (Return, followed by tilde and period) or | |
11361 | @kbd{@key{RET}~@key{C-d}} (Return, followed by tilde and control-D). | |
11362 | @end table | |
11363 | ||
6d2ebf8b | 11364 | @node Z8000 |
104c1213 JM |
11365 | @subsection Zilog Z8000 |
11366 | ||
11367 | @cindex Z8000 | |
11368 | @cindex simulator, Z8000 | |
11369 | @cindex Zilog Z8000 simulator | |
11370 | ||
11371 | When configured for debugging Zilog Z8000 targets, @value{GDBN} includes | |
11372 | a Z8000 simulator. | |
11373 | ||
11374 | For the Z8000 family, @samp{target sim} simulates either the Z8002 (the | |
11375 | unsegmented variant of the Z8000 architecture) or the Z8001 (the | |
11376 | segmented variant). The simulator recognizes which architecture is | |
11377 | appropriate by inspecting the object code. | |
11378 | ||
11379 | @table @code | |
11380 | @item target sim @var{args} | |
11381 | @kindex sim | |
d4f3574e | 11382 | @kindex target sim@r{, with Z8000} |
104c1213 JM |
11383 | Debug programs on a simulated CPU. If the simulator supports setup |
11384 | options, specify them via @var{args}. | |
11385 | @end table | |
11386 | ||
11387 | @noindent | |
11388 | After specifying this target, you can debug programs for the simulated | |
11389 | CPU in the same style as programs for your host computer; use the | |
11390 | @code{file} command to load a new program image, the @code{run} command | |
11391 | to run your program, and so on. | |
11392 | ||
d4f3574e SS |
11393 | As well as making available all the usual machine registers |
11394 | (@pxref{Registers, ,Registers}), the Z8000 simulator provides three | |
11395 | additional items of information as specially named registers: | |
104c1213 JM |
11396 | |
11397 | @table @code | |
11398 | ||
11399 | @item cycles | |
11400 | Counts clock-ticks in the simulator. | |
11401 | ||
11402 | @item insts | |
11403 | Counts instructions run in the simulator. | |
11404 | ||
11405 | @item time | |
11406 | Execution time in 60ths of a second. | |
11407 | ||
11408 | @end table | |
11409 | ||
11410 | You can refer to these values in @value{GDBN} expressions with the usual | |
11411 | conventions; for example, @w{@samp{b fputc if $cycles>5000}} sets a | |
11412 | conditional breakpoint that suspends only after at least 5000 | |
11413 | simulated clock ticks. | |
11414 | ||
6d2ebf8b | 11415 | @node Architectures |
104c1213 JM |
11416 | @section Architectures |
11417 | ||
11418 | This section describes characteristics of architectures that affect | |
2df3850c | 11419 | all uses of @value{GDBN} with the architecture, both native and cross. |
104c1213 JM |
11420 | |
11421 | @menu | |
11422 | * A29K:: | |
11423 | * Alpha:: | |
11424 | * MIPS:: | |
11425 | @end menu | |
11426 | ||
6d2ebf8b | 11427 | @node A29K |
104c1213 JM |
11428 | @subsection A29K |
11429 | ||
11430 | @table @code | |
11431 | ||
11432 | @kindex set rstack_high_address | |
11433 | @cindex AMD 29K register stack | |
11434 | @cindex register stack, AMD29K | |
11435 | @item set rstack_high_address @var{address} | |
11436 | On AMD 29000 family processors, registers are saved in a separate | |
d4f3574e | 11437 | @dfn{register stack}. There is no way for @value{GDBN} to determine the |
104c1213 JM |
11438 | extent of this stack. Normally, @value{GDBN} just assumes that the |
11439 | stack is ``large enough''. This may result in @value{GDBN} referencing | |
11440 | memory locations that do not exist. If necessary, you can get around | |
11441 | this problem by specifying the ending address of the register stack with | |
11442 | the @code{set rstack_high_address} command. The argument should be an | |
11443 | address, which you probably want to precede with @samp{0x} to specify in | |
11444 | hexadecimal. | |
11445 | ||
11446 | @kindex show rstack_high_address | |
11447 | @item show rstack_high_address | |
11448 | Display the current limit of the register stack, on AMD 29000 family | |
11449 | processors. | |
11450 | ||
11451 | @end table | |
11452 | ||
6d2ebf8b | 11453 | @node Alpha |
104c1213 JM |
11454 | @subsection Alpha |
11455 | ||
11456 | See the following section. | |
11457 | ||
6d2ebf8b | 11458 | @node MIPS |
104c1213 JM |
11459 | @subsection MIPS |
11460 | ||
11461 | @cindex stack on Alpha | |
11462 | @cindex stack on MIPS | |
11463 | @cindex Alpha stack | |
11464 | @cindex MIPS stack | |
11465 | Alpha- and MIPS-based computers use an unusual stack frame, which | |
11466 | sometimes requires @value{GDBN} to search backward in the object code to | |
11467 | find the beginning of a function. | |
11468 | ||
11469 | @cindex response time, MIPS debugging | |
11470 | To improve response time (especially for embedded applications, where | |
11471 | @value{GDBN} may be restricted to a slow serial line for this search) | |
11472 | you may want to limit the size of this search, using one of these | |
11473 | commands: | |
11474 | ||
11475 | @table @code | |
00e4a2e4 | 11476 | @cindex @code{heuristic-fence-post} (Alpha, MIPS) |
104c1213 JM |
11477 | @item set heuristic-fence-post @var{limit} |
11478 | Restrict @value{GDBN} to examining at most @var{limit} bytes in its | |
11479 | search for the beginning of a function. A value of @var{0} (the | |
11480 | default) means there is no limit. However, except for @var{0}, the | |
11481 | larger the limit the more bytes @code{heuristic-fence-post} must search | |
11482 | and therefore the longer it takes to run. | |
11483 | ||
11484 | @item show heuristic-fence-post | |
11485 | Display the current limit. | |
11486 | @end table | |
11487 | ||
11488 | @noindent | |
11489 | These commands are available @emph{only} when @value{GDBN} is configured | |
11490 | for debugging programs on Alpha or MIPS processors. | |
11491 | ||
11492 | ||
6d2ebf8b | 11493 | @node Controlling GDB |
c906108c SS |
11494 | @chapter Controlling @value{GDBN} |
11495 | ||
53a5351d JM |
11496 | You can alter the way @value{GDBN} interacts with you by using the |
11497 | @code{set} command. For commands controlling how @value{GDBN} displays | |
d4f3574e | 11498 | data, see @ref{Print Settings, ,Print settings}. Other settings are |
53a5351d | 11499 | described here. |
c906108c SS |
11500 | |
11501 | @menu | |
11502 | * Prompt:: Prompt | |
11503 | * Editing:: Command editing | |
11504 | * History:: Command history | |
11505 | * Screen Size:: Screen size | |
11506 | * Numbers:: Numbers | |
11507 | * Messages/Warnings:: Optional warnings and messages | |
5d161b24 | 11508 | * Debugging Output:: Optional messages about internal happenings |
c906108c SS |
11509 | @end menu |
11510 | ||
6d2ebf8b | 11511 | @node Prompt |
c906108c SS |
11512 | @section Prompt |
11513 | ||
11514 | @cindex prompt | |
11515 | ||
11516 | @value{GDBN} indicates its readiness to read a command by printing a string | |
11517 | called the @dfn{prompt}. This string is normally @samp{(@value{GDBP})}. You | |
11518 | can change the prompt string with the @code{set prompt} command. For | |
11519 | instance, when debugging @value{GDBN} with @value{GDBN}, it is useful to change | |
5d161b24 | 11520 | the prompt in one of the @value{GDBN} sessions so that you can always tell |
c906108c SS |
11521 | which one you are talking to. |
11522 | ||
d4f3574e | 11523 | @emph{Note:} @code{set prompt} does not add a space for you after the |
c906108c SS |
11524 | prompt you set. This allows you to set a prompt which ends in a space |
11525 | or a prompt that does not. | |
11526 | ||
11527 | @table @code | |
11528 | @kindex set prompt | |
11529 | @item set prompt @var{newprompt} | |
11530 | Directs @value{GDBN} to use @var{newprompt} as its prompt string henceforth. | |
11531 | ||
11532 | @kindex show prompt | |
11533 | @item show prompt | |
11534 | Prints a line of the form: @samp{Gdb's prompt is: @var{your-prompt}} | |
11535 | @end table | |
11536 | ||
6d2ebf8b | 11537 | @node Editing |
c906108c SS |
11538 | @section Command editing |
11539 | @cindex readline | |
11540 | @cindex command line editing | |
11541 | ||
11542 | @value{GDBN} reads its input commands via the @dfn{readline} interface. This | |
11543 | @sc{gnu} library provides consistent behavior for programs which provide a | |
11544 | command line interface to the user. Advantages are @sc{gnu} Emacs-style | |
11545 | or @dfn{vi}-style inline editing of commands, @code{csh}-like history | |
11546 | substitution, and a storage and recall of command history across | |
11547 | debugging sessions. | |
11548 | ||
11549 | You may control the behavior of command line editing in @value{GDBN} with the | |
11550 | command @code{set}. | |
11551 | ||
11552 | @table @code | |
11553 | @kindex set editing | |
11554 | @cindex editing | |
11555 | @item set editing | |
11556 | @itemx set editing on | |
11557 | Enable command line editing (enabled by default). | |
11558 | ||
11559 | @item set editing off | |
11560 | Disable command line editing. | |
11561 | ||
11562 | @kindex show editing | |
11563 | @item show editing | |
11564 | Show whether command line editing is enabled. | |
11565 | @end table | |
11566 | ||
6d2ebf8b | 11567 | @node History |
c906108c SS |
11568 | @section Command history |
11569 | ||
11570 | @value{GDBN} can keep track of the commands you type during your | |
11571 | debugging sessions, so that you can be certain of precisely what | |
11572 | happened. Use these commands to manage the @value{GDBN} command | |
11573 | history facility. | |
11574 | ||
11575 | @table @code | |
11576 | @cindex history substitution | |
11577 | @cindex history file | |
11578 | @kindex set history filename | |
11579 | @kindex GDBHISTFILE | |
11580 | @item set history filename @var{fname} | |
11581 | Set the name of the @value{GDBN} command history file to @var{fname}. | |
11582 | This is the file where @value{GDBN} reads an initial command history | |
11583 | list, and where it writes the command history from this session when it | |
11584 | exits. You can access this list through history expansion or through | |
11585 | the history command editing characters listed below. This file defaults | |
11586 | to the value of the environment variable @code{GDBHISTFILE}, or to | |
d4f3574e SS |
11587 | @file{./.gdb_history} (@file{./_gdb_history} on MS-DOS) if this variable |
11588 | is not set. | |
c906108c SS |
11589 | |
11590 | @cindex history save | |
11591 | @kindex set history save | |
11592 | @item set history save | |
11593 | @itemx set history save on | |
11594 | Record command history in a file, whose name may be specified with the | |
11595 | @code{set history filename} command. By default, this option is disabled. | |
11596 | ||
11597 | @item set history save off | |
11598 | Stop recording command history in a file. | |
11599 | ||
11600 | @cindex history size | |
11601 | @kindex set history size | |
11602 | @item set history size @var{size} | |
11603 | Set the number of commands which @value{GDBN} keeps in its history list. | |
11604 | This defaults to the value of the environment variable | |
11605 | @code{HISTSIZE}, or to 256 if this variable is not set. | |
11606 | @end table | |
11607 | ||
11608 | @cindex history expansion | |
11609 | History expansion assigns special meaning to the character @kbd{!}. | |
11610 | @ifset have-readline-appendices | |
11611 | @xref{Event Designators}. | |
11612 | @end ifset | |
11613 | ||
11614 | Since @kbd{!} is also the logical not operator in C, history expansion | |
11615 | is off by default. If you decide to enable history expansion with the | |
11616 | @code{set history expansion on} command, you may sometimes need to | |
11617 | follow @kbd{!} (when it is used as logical not, in an expression) with | |
11618 | a space or a tab to prevent it from being expanded. The readline | |
11619 | history facilities do not attempt substitution on the strings | |
11620 | @kbd{!=} and @kbd{!(}, even when history expansion is enabled. | |
11621 | ||
11622 | The commands to control history expansion are: | |
11623 | ||
11624 | @table @code | |
11625 | @kindex set history expansion | |
11626 | @item set history expansion on | |
11627 | @itemx set history expansion | |
11628 | Enable history expansion. History expansion is off by default. | |
11629 | ||
11630 | @item set history expansion off | |
11631 | Disable history expansion. | |
11632 | ||
11633 | The readline code comes with more complete documentation of | |
11634 | editing and history expansion features. Users unfamiliar with @sc{gnu} Emacs | |
11635 | or @code{vi} may wish to read it. | |
11636 | @ifset have-readline-appendices | |
11637 | @xref{Command Line Editing}. | |
11638 | @end ifset | |
11639 | ||
11640 | @c @group | |
11641 | @kindex show history | |
11642 | @item show history | |
11643 | @itemx show history filename | |
11644 | @itemx show history save | |
11645 | @itemx show history size | |
11646 | @itemx show history expansion | |
11647 | These commands display the state of the @value{GDBN} history parameters. | |
11648 | @code{show history} by itself displays all four states. | |
11649 | @c @end group | |
11650 | @end table | |
11651 | ||
11652 | @table @code | |
41afff9a | 11653 | @kindex shows |
c906108c SS |
11654 | @item show commands |
11655 | Display the last ten commands in the command history. | |
11656 | ||
11657 | @item show commands @var{n} | |
11658 | Print ten commands centered on command number @var{n}. | |
11659 | ||
11660 | @item show commands + | |
11661 | Print ten commands just after the commands last printed. | |
11662 | @end table | |
11663 | ||
6d2ebf8b | 11664 | @node Screen Size |
c906108c SS |
11665 | @section Screen size |
11666 | @cindex size of screen | |
11667 | @cindex pauses in output | |
11668 | ||
11669 | Certain commands to @value{GDBN} may produce large amounts of | |
11670 | information output to the screen. To help you read all of it, | |
11671 | @value{GDBN} pauses and asks you for input at the end of each page of | |
11672 | output. Type @key{RET} when you want to continue the output, or @kbd{q} | |
11673 | to discard the remaining output. Also, the screen width setting | |
11674 | determines when to wrap lines of output. Depending on what is being | |
11675 | printed, @value{GDBN} tries to break the line at a readable place, | |
11676 | rather than simply letting it overflow onto the following line. | |
11677 | ||
d4f3574e SS |
11678 | Normally @value{GDBN} knows the size of the screen from the terminal |
11679 | driver software. For example, on Unix @value{GDBN} uses the termcap data base | |
c906108c | 11680 | together with the value of the @code{TERM} environment variable and the |
d4f3574e | 11681 | @code{stty rows} and @code{stty cols} settings. If this is not correct, |
c906108c SS |
11682 | you can override it with the @code{set height} and @code{set |
11683 | width} commands: | |
11684 | ||
11685 | @table @code | |
11686 | @kindex set height | |
11687 | @kindex set width | |
11688 | @kindex show width | |
11689 | @kindex show height | |
11690 | @item set height @var{lpp} | |
11691 | @itemx show height | |
11692 | @itemx set width @var{cpl} | |
11693 | @itemx show width | |
11694 | These @code{set} commands specify a screen height of @var{lpp} lines and | |
11695 | a screen width of @var{cpl} characters. The associated @code{show} | |
11696 | commands display the current settings. | |
11697 | ||
5d161b24 DB |
11698 | If you specify a height of zero lines, @value{GDBN} does not pause during |
11699 | output no matter how long the output is. This is useful if output is to a | |
c906108c SS |
11700 | file or to an editor buffer. |
11701 | ||
11702 | Likewise, you can specify @samp{set width 0} to prevent @value{GDBN} | |
11703 | from wrapping its output. | |
11704 | @end table | |
11705 | ||
6d2ebf8b | 11706 | @node Numbers |
c906108c SS |
11707 | @section Numbers |
11708 | @cindex number representation | |
11709 | @cindex entering numbers | |
11710 | ||
2df3850c JM |
11711 | You can always enter numbers in octal, decimal, or hexadecimal in |
11712 | @value{GDBN} by the usual conventions: octal numbers begin with | |
11713 | @samp{0}, decimal numbers end with @samp{.}, and hexadecimal numbers | |
11714 | begin with @samp{0x}. Numbers that begin with none of these are, by | |
11715 | default, entered in base 10; likewise, the default display for | |
11716 | numbers---when no particular format is specified---is base 10. You can | |
11717 | change the default base for both input and output with the @code{set | |
11718 | radix} command. | |
c906108c SS |
11719 | |
11720 | @table @code | |
11721 | @kindex set input-radix | |
11722 | @item set input-radix @var{base} | |
11723 | Set the default base for numeric input. Supported choices | |
11724 | for @var{base} are decimal 8, 10, or 16. @var{base} must itself be | |
11725 | specified either unambiguously or using the current default radix; for | |
11726 | example, any of | |
11727 | ||
11728 | @smallexample | |
11729 | set radix 012 | |
11730 | set radix 10. | |
11731 | set radix 0xa | |
11732 | @end smallexample | |
11733 | ||
11734 | @noindent | |
11735 | sets the base to decimal. On the other hand, @samp{set radix 10} | |
11736 | leaves the radix unchanged no matter what it was. | |
11737 | ||
11738 | @kindex set output-radix | |
11739 | @item set output-radix @var{base} | |
11740 | Set the default base for numeric display. Supported choices | |
11741 | for @var{base} are decimal 8, 10, or 16. @var{base} must itself be | |
11742 | specified either unambiguously or using the current default radix. | |
11743 | ||
11744 | @kindex show input-radix | |
11745 | @item show input-radix | |
11746 | Display the current default base for numeric input. | |
11747 | ||
11748 | @kindex show output-radix | |
11749 | @item show output-radix | |
11750 | Display the current default base for numeric display. | |
11751 | @end table | |
11752 | ||
6d2ebf8b | 11753 | @node Messages/Warnings |
c906108c SS |
11754 | @section Optional warnings and messages |
11755 | ||
2df3850c JM |
11756 | By default, @value{GDBN} is silent about its inner workings. If you are |
11757 | running on a slow machine, you may want to use the @code{set verbose} | |
11758 | command. This makes @value{GDBN} tell you when it does a lengthy | |
11759 | internal operation, so you will not think it has crashed. | |
c906108c SS |
11760 | |
11761 | Currently, the messages controlled by @code{set verbose} are those | |
11762 | which announce that the symbol table for a source file is being read; | |
11763 | see @code{symbol-file} in @ref{Files, ,Commands to specify files}. | |
11764 | ||
11765 | @table @code | |
11766 | @kindex set verbose | |
11767 | @item set verbose on | |
11768 | Enables @value{GDBN} output of certain informational messages. | |
11769 | ||
11770 | @item set verbose off | |
11771 | Disables @value{GDBN} output of certain informational messages. | |
11772 | ||
11773 | @kindex show verbose | |
11774 | @item show verbose | |
11775 | Displays whether @code{set verbose} is on or off. | |
11776 | @end table | |
11777 | ||
2df3850c JM |
11778 | By default, if @value{GDBN} encounters bugs in the symbol table of an |
11779 | object file, it is silent; but if you are debugging a compiler, you may | |
11780 | find this information useful (@pxref{Symbol Errors, ,Errors reading | |
11781 | symbol files}). | |
c906108c SS |
11782 | |
11783 | @table @code | |
2df3850c | 11784 | |
c906108c SS |
11785 | @kindex set complaints |
11786 | @item set complaints @var{limit} | |
2df3850c JM |
11787 | Permits @value{GDBN} to output @var{limit} complaints about each type of |
11788 | unusual symbols before becoming silent about the problem. Set | |
11789 | @var{limit} to zero to suppress all complaints; set it to a large number | |
11790 | to prevent complaints from being suppressed. | |
c906108c SS |
11791 | |
11792 | @kindex show complaints | |
11793 | @item show complaints | |
11794 | Displays how many symbol complaints @value{GDBN} is permitted to produce. | |
2df3850c | 11795 | |
c906108c SS |
11796 | @end table |
11797 | ||
11798 | By default, @value{GDBN} is cautious, and asks what sometimes seems to be a | |
11799 | lot of stupid questions to confirm certain commands. For example, if | |
11800 | you try to run a program which is already running: | |
11801 | ||
11802 | @example | |
11803 | (@value{GDBP}) run | |
11804 | The program being debugged has been started already. | |
11805 | Start it from the beginning? (y or n) | |
11806 | @end example | |
11807 | ||
11808 | If you are willing to unflinchingly face the consequences of your own | |
11809 | commands, you can disable this ``feature'': | |
11810 | ||
11811 | @table @code | |
2df3850c | 11812 | |
c906108c SS |
11813 | @kindex set confirm |
11814 | @cindex flinching | |
11815 | @cindex confirmation | |
11816 | @cindex stupid questions | |
11817 | @item set confirm off | |
11818 | Disables confirmation requests. | |
11819 | ||
11820 | @item set confirm on | |
11821 | Enables confirmation requests (the default). | |
11822 | ||
11823 | @kindex show confirm | |
11824 | @item show confirm | |
11825 | Displays state of confirmation requests. | |
2df3850c | 11826 | |
c906108c SS |
11827 | @end table |
11828 | ||
6d2ebf8b | 11829 | @node Debugging Output |
5d161b24 DB |
11830 | @section Optional messages about internal happenings |
11831 | @table @code | |
11832 | @kindex set debug arch | |
11833 | @item set debug arch | |
11834 | Turns on or off display of gdbarch debugging info. The default is off | |
11835 | @kindex show debug arch | |
11836 | @item show debug arch | |
11837 | Displays the current state of displaying gdbarch debugging info. | |
11838 | @kindex set debug event | |
11839 | @item set debug event | |
11840 | Turns on or off display of @value{GDBN} event debugging info. The | |
11841 | default is off. | |
11842 | @kindex show debug event | |
11843 | @item show debug event | |
11844 | Displays the current state of displaying @value{GDBN} event debugging | |
11845 | info. | |
11846 | @kindex set debug expression | |
11847 | @item set debug expression | |
11848 | Turns on or off display of @value{GDBN} expression debugging info. The | |
11849 | default is off. | |
11850 | @kindex show debug expression | |
11851 | @item show debug expression | |
11852 | Displays the current state of displaying @value{GDBN} expression | |
11853 | debugging info. | |
11854 | @kindex set debug overload | |
11855 | @item set debug overload | |
11856 | Turns on or off display of @value{GDBN} C++ overload debugging | |
11857 | info. This includes info such as ranking of functions, etc. The default | |
11858 | is off. | |
11859 | @kindex show debug overload | |
11860 | @item show debug overload | |
11861 | Displays the current state of displaying @value{GDBN} C++ overload | |
11862 | debugging info. | |
11863 | @kindex set debug remote | |
11864 | @cindex packets, reporting on stdout | |
11865 | @cindex serial connections, debugging | |
11866 | @item set debug remote | |
11867 | Turns on or off display of reports on all packets sent back and forth across | |
11868 | the serial line to the remote machine. The info is printed on the | |
11869 | @value{GDBN} standard output stream. The default is off. | |
11870 | @kindex show debug remote | |
11871 | @item show debug remote | |
11872 | Displays the state of display of remote packets. | |
11873 | @kindex set debug serial | |
11874 | @item set debug serial | |
11875 | Turns on or off display of @value{GDBN} serial debugging info. The | |
11876 | default is off. | |
11877 | @kindex show debug serial | |
11878 | @item show debug serial | |
11879 | Displays the current state of displaying @value{GDBN} serial debugging | |
11880 | info. | |
11881 | @kindex set debug target | |
11882 | @item set debug target | |
11883 | Turns on or off display of @value{GDBN} target debugging info. This info | |
11884 | includes what is going on at the target level of GDB, as it happens. The | |
11885 | default is off. | |
11886 | @kindex show debug target | |
11887 | @item show debug target | |
11888 | Displays the current state of displaying @value{GDBN} target debugging | |
11889 | info. | |
11890 | @kindex set debug varobj | |
11891 | @item set debug varobj | |
11892 | Turns on or off display of @value{GDBN} variable object debugging | |
11893 | info. The default is off. | |
11894 | @kindex show debug varobj | |
11895 | @item show debug varobj | |
11896 | Displays the current state of displaying @value{GDBN} variable object | |
11897 | debugging info. | |
11898 | @end table | |
11899 | ||
6d2ebf8b | 11900 | @node Sequences |
c906108c SS |
11901 | @chapter Canned Sequences of Commands |
11902 | ||
11903 | Aside from breakpoint commands (@pxref{Break Commands, ,Breakpoint | |
2df3850c JM |
11904 | command lists}), @value{GDBN} provides two ways to store sequences of |
11905 | commands for execution as a unit: user-defined commands and command | |
11906 | files. | |
c906108c SS |
11907 | |
11908 | @menu | |
11909 | * Define:: User-defined commands | |
11910 | * Hooks:: User-defined command hooks | |
11911 | * Command Files:: Command files | |
11912 | * Output:: Commands for controlled output | |
11913 | @end menu | |
11914 | ||
6d2ebf8b | 11915 | @node Define |
c906108c SS |
11916 | @section User-defined commands |
11917 | ||
11918 | @cindex user-defined command | |
2df3850c JM |
11919 | A @dfn{user-defined command} is a sequence of @value{GDBN} commands to |
11920 | which you assign a new name as a command. This is done with the | |
11921 | @code{define} command. User commands may accept up to 10 arguments | |
11922 | separated by whitespace. Arguments are accessed within the user command | |
11923 | via @var{$arg0@dots{}$arg9}. A trivial example: | |
c906108c SS |
11924 | |
11925 | @smallexample | |
11926 | define adder | |
11927 | print $arg0 + $arg1 + $arg2 | |
11928 | @end smallexample | |
11929 | ||
d4f3574e SS |
11930 | @noindent |
11931 | To execute the command use: | |
c906108c SS |
11932 | |
11933 | @smallexample | |
11934 | adder 1 2 3 | |
11935 | @end smallexample | |
11936 | ||
d4f3574e SS |
11937 | @noindent |
11938 | This defines the command @code{adder}, which prints the sum of | |
5d161b24 | 11939 | its three arguments. Note the arguments are text substitutions, so they may |
c906108c SS |
11940 | reference variables, use complex expressions, or even perform inferior |
11941 | functions calls. | |
11942 | ||
11943 | @table @code | |
2df3850c | 11944 | |
c906108c SS |
11945 | @kindex define |
11946 | @item define @var{commandname} | |
11947 | Define a command named @var{commandname}. If there is already a command | |
11948 | by that name, you are asked to confirm that you want to redefine it. | |
11949 | ||
11950 | The definition of the command is made up of other @value{GDBN} command lines, | |
11951 | which are given following the @code{define} command. The end of these | |
11952 | commands is marked by a line containing @code{end}. | |
11953 | ||
11954 | @kindex if | |
11955 | @kindex else | |
11956 | @item if | |
11957 | Takes a single argument, which is an expression to evaluate. | |
11958 | It is followed by a series of commands that are executed | |
11959 | only if the expression is true (nonzero). | |
11960 | There can then optionally be a line @code{else}, followed | |
11961 | by a series of commands that are only executed if the expression | |
11962 | was false. The end of the list is marked by a line containing @code{end}. | |
11963 | ||
11964 | @kindex while | |
11965 | @item while | |
11966 | The syntax is similar to @code{if}: the command takes a single argument, | |
11967 | which is an expression to evaluate, and must be followed by the commands to | |
11968 | execute, one per line, terminated by an @code{end}. | |
11969 | The commands are executed repeatedly as long as the expression | |
11970 | evaluates to true. | |
11971 | ||
11972 | @kindex document | |
11973 | @item document @var{commandname} | |
11974 | Document the user-defined command @var{commandname}, so that it can be | |
5d161b24 DB |
11975 | accessed by @code{help}. The command @var{commandname} must already be |
11976 | defined. This command reads lines of documentation just as @code{define} | |
11977 | reads the lines of the command definition, ending with @code{end}. | |
11978 | After the @code{document} command is finished, @code{help} on command | |
c906108c SS |
11979 | @var{commandname} displays the documentation you have written. |
11980 | ||
11981 | You may use the @code{document} command again to change the | |
11982 | documentation of a command. Redefining the command with @code{define} | |
11983 | does not change the documentation. | |
11984 | ||
11985 | @kindex help user-defined | |
11986 | @item help user-defined | |
11987 | List all user-defined commands, with the first line of the documentation | |
11988 | (if any) for each. | |
11989 | ||
11990 | @kindex show user | |
11991 | @item show user | |
11992 | @itemx show user @var{commandname} | |
2df3850c JM |
11993 | Display the @value{GDBN} commands used to define @var{commandname} (but |
11994 | not its documentation). If no @var{commandname} is given, display the | |
c906108c | 11995 | definitions for all user-defined commands. |
2df3850c | 11996 | |
c906108c SS |
11997 | @end table |
11998 | ||
11999 | When user-defined commands are executed, the | |
12000 | commands of the definition are not printed. An error in any command | |
12001 | stops execution of the user-defined command. | |
12002 | ||
12003 | If used interactively, commands that would ask for confirmation proceed | |
5d161b24 DB |
12004 | without asking when used inside a user-defined command. Many @value{GDBN} |
12005 | commands that normally print messages to say what they are doing omit the | |
c906108c SS |
12006 | messages when used in a user-defined command. |
12007 | ||
6d2ebf8b | 12008 | @node Hooks |
c906108c | 12009 | @section User-defined command hooks |
d4f3574e SS |
12010 | @cindex command hooks |
12011 | @cindex hooks, for commands | |
c78b4128 | 12012 | @cindex hooks, pre-command |
c906108c | 12013 | |
c78b4128 EZ |
12014 | @kindex hook |
12015 | @kindex hook- | |
12016 | You may define @dfn{hooks}, which are a special kind of user-defined | |
c906108c SS |
12017 | command. Whenever you run the command @samp{foo}, if the user-defined |
12018 | command @samp{hook-foo} exists, it is executed (with no arguments) | |
12019 | before that command. | |
12020 | ||
c78b4128 EZ |
12021 | @cindex hooks, post-command |
12022 | @kindex hookpost | |
12023 | @kindex hookpost- | |
12024 | A hook may also be defined which is run after the command you executed. | |
12025 | Whenever you run the command @samp{foo}, if the user-defined command | |
12026 | @samp{hookpost-foo} exists, it is executed (with no arguments) after | |
12027 | that command. Post-execution hooks may exist simultaneously with | |
12028 | pre-execution hooks, for the same command. | |
12029 | ||
12030 | It is valid for a hook to call the command which it hooks. If this | |
12031 | occurs, the hook is not re-executed, thereby avoiding infinte recursion. | |
12032 | ||
12033 | @c It would be nice if hookpost could be passed a parameter indicating | |
12034 | @c if the command it hooks executed properly or not. FIXME! | |
12035 | ||
d4f3574e | 12036 | @kindex stop@r{, a pseudo-command} |
c906108c SS |
12037 | In addition, a pseudo-command, @samp{stop} exists. Defining |
12038 | (@samp{hook-stop}) makes the associated commands execute every time | |
12039 | execution stops in your program: before breakpoint commands are run, | |
12040 | displays are printed, or the stack frame is printed. | |
12041 | ||
c906108c SS |
12042 | For example, to ignore @code{SIGALRM} signals while |
12043 | single-stepping, but treat them normally during normal execution, | |
12044 | you could define: | |
12045 | ||
12046 | @example | |
12047 | define hook-stop | |
12048 | handle SIGALRM nopass | |
12049 | end | |
12050 | ||
12051 | define hook-run | |
12052 | handle SIGALRM pass | |
12053 | end | |
12054 | ||
12055 | define hook-continue | |
12056 | handle SIGLARM pass | |
12057 | end | |
12058 | @end example | |
c906108c | 12059 | |
c78b4128 EZ |
12060 | As a further example, to hook at the begining and end of the @code{echo} |
12061 | command, and to add extra text to the beginning and end of the message, | |
12062 | you could define: | |
12063 | ||
12064 | @example | |
12065 | define hook-echo | |
12066 | echo <<<--- | |
12067 | end | |
12068 | ||
12069 | define hookpost-echo | |
12070 | echo --->>>\n | |
12071 | end | |
12072 | ||
12073 | (@value{GDBP}) echo Hello World | |
12074 | <<<---Hello World--->>> | |
12075 | (@value{GDBP}) | |
12076 | ||
12077 | @end example | |
12078 | ||
c906108c SS |
12079 | You can define a hook for any single-word command in @value{GDBN}, but |
12080 | not for command aliases; you should define a hook for the basic command | |
12081 | name, e.g. @code{backtrace} rather than @code{bt}. | |
12082 | @c FIXME! So how does Joe User discover whether a command is an alias | |
12083 | @c or not? | |
12084 | If an error occurs during the execution of your hook, execution of | |
12085 | @value{GDBN} commands stops and @value{GDBN} issues a prompt | |
12086 | (before the command that you actually typed had a chance to run). | |
12087 | ||
12088 | If you try to define a hook which does not match any known command, you | |
12089 | get a warning from the @code{define} command. | |
12090 | ||
6d2ebf8b | 12091 | @node Command Files |
c906108c SS |
12092 | @section Command files |
12093 | ||
12094 | @cindex command files | |
5d161b24 DB |
12095 | A command file for @value{GDBN} is a file of lines that are @value{GDBN} |
12096 | commands. Comments (lines starting with @kbd{#}) may also be included. | |
12097 | An empty line in a command file does nothing; it does not mean to repeat | |
c906108c SS |
12098 | the last command, as it would from the terminal. |
12099 | ||
12100 | @cindex init file | |
12101 | @cindex @file{.gdbinit} | |
d4f3574e | 12102 | @cindex @file{gdb.ini} |
c906108c | 12103 | When you start @value{GDBN}, it automatically executes commands from its |
bf0184be ND |
12104 | @dfn{init files}. These are files named @file{.gdbinit} on Unix and |
12105 | @file{gdb.ini} on DOS/Windows. During startup, @value{GDBN} does the | |
12106 | following: | |
12107 | ||
12108 | @enumerate | |
12109 | @item | |
12110 | Reads the init file (if any) in your home directory@footnote{On | |
12111 | DOS/Windows systems, the home directory is the one pointed to by the | |
12112 | @code{HOME} environment variable.}. | |
12113 | ||
12114 | @item | |
12115 | Processes command line options and operands. | |
12116 | ||
12117 | @item | |
12118 | Reads the init file (if any) in the current working directory. | |
12119 | ||
12120 | @item | |
12121 | Reads command files specified by the @samp{-x} option. | |
12122 | @end enumerate | |
12123 | ||
12124 | The init file in your home directory can set options (such as @samp{set | |
12125 | complaints}) that affect subsequent processing of command line options | |
12126 | and operands. Init files are not executed if you use the @samp{-nx} | |
12127 | option (@pxref{Mode Options, ,Choosing modes}). | |
c906108c | 12128 | |
c906108c SS |
12129 | @cindex init file name |
12130 | On some configurations of @value{GDBN}, the init file is known by a | |
12131 | different name (these are typically environments where a specialized | |
12132 | form of @value{GDBN} may need to coexist with other forms, hence a | |
12133 | different name for the specialized version's init file). These are the | |
12134 | environments with special init file names: | |
12135 | ||
00e4a2e4 | 12136 | @cindex @file{.vxgdbinit} |
c906108c SS |
12137 | @itemize @bullet |
12138 | @item | |
00e4a2e4 | 12139 | VxWorks (Wind River Systems real-time OS): @file{.vxgdbinit} |
c906108c | 12140 | |
00e4a2e4 | 12141 | @cindex @file{.os68gdbinit} |
c906108c | 12142 | @item |
00e4a2e4 | 12143 | OS68K (Enea Data Systems real-time OS): @file{.os68gdbinit} |
c906108c | 12144 | |
00e4a2e4 | 12145 | @cindex @file{.esgdbinit} |
c906108c | 12146 | @item |
00e4a2e4 | 12147 | ES-1800 (Ericsson Telecom AB M68000 emulator): @file{.esgdbinit} |
c906108c | 12148 | @end itemize |
c906108c SS |
12149 | |
12150 | You can also request the execution of a command file with the | |
12151 | @code{source} command: | |
12152 | ||
12153 | @table @code | |
12154 | @kindex source | |
12155 | @item source @var{filename} | |
12156 | Execute the command file @var{filename}. | |
12157 | @end table | |
12158 | ||
12159 | The lines in a command file are executed sequentially. They are not | |
12160 | printed as they are executed. An error in any command terminates execution | |
12161 | of the command file. | |
12162 | ||
12163 | Commands that would ask for confirmation if used interactively proceed | |
12164 | without asking when used in a command file. Many @value{GDBN} commands that | |
12165 | normally print messages to say what they are doing omit the messages | |
12166 | when called from command files. | |
12167 | ||
6d2ebf8b | 12168 | @node Output |
c906108c SS |
12169 | @section Commands for controlled output |
12170 | ||
12171 | During the execution of a command file or a user-defined command, normal | |
12172 | @value{GDBN} output is suppressed; the only output that appears is what is | |
12173 | explicitly printed by the commands in the definition. This section | |
12174 | describes three commands useful for generating exactly the output you | |
12175 | want. | |
12176 | ||
12177 | @table @code | |
12178 | @kindex echo | |
12179 | @item echo @var{text} | |
12180 | @c I do not consider backslash-space a standard C escape sequence | |
12181 | @c because it is not in ANSI. | |
12182 | Print @var{text}. Nonprinting characters can be included in | |
12183 | @var{text} using C escape sequences, such as @samp{\n} to print a | |
12184 | newline. @strong{No newline is printed unless you specify one.} | |
12185 | In addition to the standard C escape sequences, a backslash followed | |
12186 | by a space stands for a space. This is useful for displaying a | |
12187 | string with spaces at the beginning or the end, since leading and | |
5d161b24 | 12188 | trailing spaces are otherwise trimmed from all arguments. |
c906108c SS |
12189 | To print @samp{@w{ }and foo =@w{ }}, use the command |
12190 | @samp{echo \@w{ }and foo = \@w{ }}. | |
12191 | ||
12192 | A backslash at the end of @var{text} can be used, as in C, to continue | |
12193 | the command onto subsequent lines. For example, | |
12194 | ||
12195 | @example | |
12196 | echo This is some text\n\ | |
12197 | which is continued\n\ | |
12198 | onto several lines.\n | |
12199 | @end example | |
12200 | ||
12201 | produces the same output as | |
12202 | ||
12203 | @example | |
12204 | echo This is some text\n | |
12205 | echo which is continued\n | |
12206 | echo onto several lines.\n | |
12207 | @end example | |
12208 | ||
12209 | @kindex output | |
12210 | @item output @var{expression} | |
12211 | Print the value of @var{expression} and nothing but that value: no | |
12212 | newlines, no @samp{$@var{nn} = }. The value is not entered in the | |
5d161b24 | 12213 | value history either. @xref{Expressions, ,Expressions}, for more information |
c906108c SS |
12214 | on expressions. |
12215 | ||
12216 | @item output/@var{fmt} @var{expression} | |
12217 | Print the value of @var{expression} in format @var{fmt}. You can use | |
12218 | the same formats as for @code{print}. @xref{Output Formats,,Output | |
12219 | formats}, for more information. | |
12220 | ||
12221 | @kindex printf | |
12222 | @item printf @var{string}, @var{expressions}@dots{} | |
12223 | Print the values of the @var{expressions} under the control of | |
12224 | @var{string}. The @var{expressions} are separated by commas and may be | |
12225 | either numbers or pointers. Their values are printed as specified by | |
12226 | @var{string}, exactly as if your program were to execute the C | |
12227 | subroutine | |
d4f3574e SS |
12228 | @c FIXME: the above implies that at least all ANSI C formats are |
12229 | @c supported, but it isn't true: %E and %G don't work (or so it seems). | |
12230 | @c Either this is a bug, or the manual should document what formats are | |
12231 | @c supported. | |
c906108c SS |
12232 | |
12233 | @example | |
12234 | printf (@var{string}, @var{expressions}@dots{}); | |
12235 | @end example | |
12236 | ||
12237 | For example, you can print two values in hex like this: | |
12238 | ||
12239 | @smallexample | |
12240 | printf "foo, bar-foo = 0x%x, 0x%x\n", foo, bar-foo | |
12241 | @end smallexample | |
12242 | ||
12243 | The only backslash-escape sequences that you can use in the format | |
12244 | string are the simple ones that consist of backslash followed by a | |
12245 | letter. | |
12246 | @end table | |
12247 | ||
6d2ebf8b | 12248 | @node Emacs |
c906108c SS |
12249 | @chapter Using @value{GDBN} under @sc{gnu} Emacs |
12250 | ||
12251 | @cindex Emacs | |
12252 | @cindex @sc{gnu} Emacs | |
12253 | A special interface allows you to use @sc{gnu} Emacs to view (and | |
12254 | edit) the source files for the program you are debugging with | |
12255 | @value{GDBN}. | |
12256 | ||
12257 | To use this interface, use the command @kbd{M-x gdb} in Emacs. Give the | |
12258 | executable file you want to debug as an argument. This command starts | |
12259 | @value{GDBN} as a subprocess of Emacs, with input and output through a newly | |
12260 | created Emacs buffer. | |
53a5351d | 12261 | @c (Do not use the @code{-tui} option to run @value{GDBN} from Emacs.) |
c906108c SS |
12262 | |
12263 | Using @value{GDBN} under Emacs is just like using @value{GDBN} normally except for two | |
12264 | things: | |
12265 | ||
12266 | @itemize @bullet | |
12267 | @item | |
12268 | All ``terminal'' input and output goes through the Emacs buffer. | |
12269 | @end itemize | |
12270 | ||
12271 | This applies both to @value{GDBN} commands and their output, and to the input | |
12272 | and output done by the program you are debugging. | |
12273 | ||
12274 | This is useful because it means that you can copy the text of previous | |
12275 | commands and input them again; you can even use parts of the output | |
12276 | in this way. | |
12277 | ||
12278 | All the facilities of Emacs' Shell mode are available for interacting | |
12279 | with your program. In particular, you can send signals the usual | |
12280 | way---for example, @kbd{C-c C-c} for an interrupt, @kbd{C-c C-z} for a | |
12281 | stop. | |
12282 | ||
12283 | @itemize @bullet | |
12284 | @item | |
12285 | @value{GDBN} displays source code through Emacs. | |
12286 | @end itemize | |
12287 | ||
12288 | Each time @value{GDBN} displays a stack frame, Emacs automatically finds the | |
12289 | source file for that frame and puts an arrow (@samp{=>}) at the | |
12290 | left margin of the current line. Emacs uses a separate buffer for | |
12291 | source display, and splits the screen to show both your @value{GDBN} session | |
12292 | and the source. | |
12293 | ||
12294 | Explicit @value{GDBN} @code{list} or search commands still produce output as | |
12295 | usual, but you probably have no reason to use them from Emacs. | |
12296 | ||
12297 | @quotation | |
12298 | @emph{Warning:} If the directory where your program resides is not your | |
12299 | current directory, it can be easy to confuse Emacs about the location of | |
12300 | the source files, in which case the auxiliary display buffer does not | |
12301 | appear to show your source. @value{GDBN} can find programs by searching your | |
12302 | environment's @code{PATH} variable, so the @value{GDBN} input and output | |
12303 | session proceeds normally; but Emacs does not get enough information | |
12304 | back from @value{GDBN} to locate the source files in this situation. To | |
12305 | avoid this problem, either start @value{GDBN} mode from the directory where | |
12306 | your program resides, or specify an absolute file name when prompted for the | |
12307 | @kbd{M-x gdb} argument. | |
12308 | ||
12309 | A similar confusion can result if you use the @value{GDBN} @code{file} command to | |
12310 | switch to debugging a program in some other location, from an existing | |
12311 | @value{GDBN} buffer in Emacs. | |
12312 | @end quotation | |
12313 | ||
12314 | By default, @kbd{M-x gdb} calls the program called @file{gdb}. If | |
12315 | you need to call @value{GDBN} by a different name (for example, if you keep | |
12316 | several configurations around, with different names) you can set the | |
12317 | Emacs variable @code{gdb-command-name}; for example, | |
12318 | ||
12319 | @example | |
12320 | (setq gdb-command-name "mygdb") | |
12321 | @end example | |
12322 | ||
12323 | @noindent | |
d4f3574e | 12324 | (preceded by @kbd{M-:} or @kbd{ESC :}, or typed in the @code{*scratch*} buffer, or |
c906108c SS |
12325 | in your @file{.emacs} file) makes Emacs call the program named |
12326 | ``@code{mygdb}'' instead. | |
12327 | ||
12328 | In the @value{GDBN} I/O buffer, you can use these special Emacs commands in | |
12329 | addition to the standard Shell mode commands: | |
12330 | ||
12331 | @table @kbd | |
12332 | @item C-h m | |
12333 | Describe the features of Emacs' @value{GDBN} Mode. | |
12334 | ||
12335 | @item M-s | |
12336 | Execute to another source line, like the @value{GDBN} @code{step} command; also | |
12337 | update the display window to show the current file and location. | |
12338 | ||
12339 | @item M-n | |
12340 | Execute to next source line in this function, skipping all function | |
12341 | calls, like the @value{GDBN} @code{next} command. Then update the display window | |
12342 | to show the current file and location. | |
12343 | ||
12344 | @item M-i | |
12345 | Execute one instruction, like the @value{GDBN} @code{stepi} command; update | |
12346 | display window accordingly. | |
12347 | ||
12348 | @item M-x gdb-nexti | |
12349 | Execute to next instruction, using the @value{GDBN} @code{nexti} command; update | |
12350 | display window accordingly. | |
12351 | ||
12352 | @item C-c C-f | |
12353 | Execute until exit from the selected stack frame, like the @value{GDBN} | |
12354 | @code{finish} command. | |
12355 | ||
12356 | @item M-c | |
12357 | Continue execution of your program, like the @value{GDBN} @code{continue} | |
12358 | command. | |
12359 | ||
12360 | @emph{Warning:} In Emacs v19, this command is @kbd{C-c C-p}. | |
12361 | ||
12362 | @item M-u | |
12363 | Go up the number of frames indicated by the numeric argument | |
12364 | (@pxref{Arguments, , Numeric Arguments, Emacs, The @sc{gnu} Emacs Manual}), | |
12365 | like the @value{GDBN} @code{up} command. | |
12366 | ||
12367 | @emph{Warning:} In Emacs v19, this command is @kbd{C-c C-u}. | |
12368 | ||
12369 | @item M-d | |
12370 | Go down the number of frames indicated by the numeric argument, like the | |
12371 | @value{GDBN} @code{down} command. | |
12372 | ||
12373 | @emph{Warning:} In Emacs v19, this command is @kbd{C-c C-d}. | |
12374 | ||
12375 | @item C-x & | |
12376 | Read the number where the cursor is positioned, and insert it at the end | |
12377 | of the @value{GDBN} I/O buffer. For example, if you wish to disassemble code | |
12378 | around an address that was displayed earlier, type @kbd{disassemble}; | |
12379 | then move the cursor to the address display, and pick up the | |
12380 | argument for @code{disassemble} by typing @kbd{C-x &}. | |
12381 | ||
12382 | You can customize this further by defining elements of the list | |
12383 | @code{gdb-print-command}; once it is defined, you can format or | |
12384 | otherwise process numbers picked up by @kbd{C-x &} before they are | |
12385 | inserted. A numeric argument to @kbd{C-x &} indicates that you | |
12386 | wish special formatting, and also acts as an index to pick an element of the | |
12387 | list. If the list element is a string, the number to be inserted is | |
12388 | formatted using the Emacs function @code{format}; otherwise the number | |
12389 | is passed as an argument to the corresponding list element. | |
12390 | @end table | |
12391 | ||
12392 | In any source file, the Emacs command @kbd{C-x SPC} (@code{gdb-break}) | |
12393 | tells @value{GDBN} to set a breakpoint on the source line point is on. | |
12394 | ||
12395 | If you accidentally delete the source-display buffer, an easy way to get | |
12396 | it back is to type the command @code{f} in the @value{GDBN} buffer, to | |
12397 | request a frame display; when you run under Emacs, this recreates | |
12398 | the source buffer if necessary to show you the context of the current | |
12399 | frame. | |
12400 | ||
12401 | The source files displayed in Emacs are in ordinary Emacs buffers | |
12402 | which are visiting the source files in the usual way. You can edit | |
12403 | the files with these buffers if you wish; but keep in mind that @value{GDBN} | |
12404 | communicates with Emacs in terms of line numbers. If you add or | |
12405 | delete lines from the text, the line numbers that @value{GDBN} knows cease | |
12406 | to correspond properly with the code. | |
12407 | ||
12408 | @c The following dropped because Epoch is nonstandard. Reactivate | |
12409 | @c if/when v19 does something similar. [email protected] 19dec1990 | |
12410 | @ignore | |
12411 | @kindex Emacs Epoch environment | |
12412 | @kindex Epoch | |
12413 | @kindex inspect | |
12414 | ||
5d161b24 | 12415 | Version 18 of @sc{gnu} Emacs has a built-in window system |
c906108c SS |
12416 | called the @code{epoch} |
12417 | environment. Users of this environment can use a new command, | |
12418 | @code{inspect} which performs identically to @code{print} except that | |
12419 | each value is printed in its own window. | |
12420 | @end ignore | |
c906108c | 12421 | |
d700128c | 12422 | @include annotate.texi |
7162c0ca | 12423 | @include gdbmi.texinfo |
d700128c | 12424 | |
6d2ebf8b | 12425 | @node GDB Bugs |
c906108c SS |
12426 | @chapter Reporting Bugs in @value{GDBN} |
12427 | @cindex bugs in @value{GDBN} | |
12428 | @cindex reporting bugs in @value{GDBN} | |
12429 | ||
12430 | Your bug reports play an essential role in making @value{GDBN} reliable. | |
12431 | ||
12432 | Reporting a bug may help you by bringing a solution to your problem, or it | |
12433 | may not. But in any case the principal function of a bug report is to help | |
12434 | the entire community by making the next version of @value{GDBN} work better. Bug | |
12435 | reports are your contribution to the maintenance of @value{GDBN}. | |
12436 | ||
12437 | In order for a bug report to serve its purpose, you must include the | |
12438 | information that enables us to fix the bug. | |
12439 | ||
12440 | @menu | |
12441 | * Bug Criteria:: Have you found a bug? | |
12442 | * Bug Reporting:: How to report bugs | |
12443 | @end menu | |
12444 | ||
6d2ebf8b | 12445 | @node Bug Criteria |
c906108c SS |
12446 | @section Have you found a bug? |
12447 | @cindex bug criteria | |
12448 | ||
12449 | If you are not sure whether you have found a bug, here are some guidelines: | |
12450 | ||
12451 | @itemize @bullet | |
12452 | @cindex fatal signal | |
12453 | @cindex debugger crash | |
12454 | @cindex crash of debugger | |
12455 | @item | |
12456 | If the debugger gets a fatal signal, for any input whatever, that is a | |
12457 | @value{GDBN} bug. Reliable debuggers never crash. | |
12458 | ||
12459 | @cindex error on valid input | |
12460 | @item | |
12461 | If @value{GDBN} produces an error message for valid input, that is a | |
12462 | bug. (Note that if you're cross debugging, the problem may also be | |
12463 | somewhere in the connection to the target.) | |
12464 | ||
12465 | @cindex invalid input | |
12466 | @item | |
12467 | If @value{GDBN} does not produce an error message for invalid input, | |
12468 | that is a bug. However, you should note that your idea of | |
12469 | ``invalid input'' might be our idea of ``an extension'' or ``support | |
12470 | for traditional practice''. | |
12471 | ||
12472 | @item | |
12473 | If you are an experienced user of debugging tools, your suggestions | |
12474 | for improvement of @value{GDBN} are welcome in any case. | |
12475 | @end itemize | |
12476 | ||
6d2ebf8b | 12477 | @node Bug Reporting |
c906108c SS |
12478 | @section How to report bugs |
12479 | @cindex bug reports | |
12480 | @cindex @value{GDBN} bugs, reporting | |
12481 | ||
c906108c SS |
12482 | A number of companies and individuals offer support for @sc{gnu} products. |
12483 | If you obtained @value{GDBN} from a support organization, we recommend you | |
12484 | contact that organization first. | |
12485 | ||
12486 | You can find contact information for many support companies and | |
12487 | individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs | |
12488 | distribution. | |
12489 | @c should add a web page ref... | |
12490 | ||
12491 | In any event, we also recommend that you send bug reports for | |
12492 | @value{GDBN} to this addresses: | |
12493 | ||
12494 | @example | |
d4f3574e | 12495 | bug-gdb@@gnu.org |
c906108c SS |
12496 | @end example |
12497 | ||
12498 | @strong{Do not send bug reports to @samp{info-gdb}, or to | |
d4f3574e | 12499 | @samp{help-gdb}, or to any newsgroups.} Most users of @value{GDBN} do |
c906108c SS |
12500 | not want to receive bug reports. Those that do have arranged to receive |
12501 | @samp{bug-gdb}. | |
12502 | ||
12503 | The mailing list @samp{bug-gdb} has a newsgroup @samp{gnu.gdb.bug} which | |
12504 | serves as a repeater. The mailing list and the newsgroup carry exactly | |
12505 | the same messages. Often people think of posting bug reports to the | |
12506 | newsgroup instead of mailing them. This appears to work, but it has one | |
12507 | problem which can be crucial: a newsgroup posting often lacks a mail | |
12508 | path back to the sender. Thus, if we need to ask for more information, | |
12509 | we may be unable to reach you. For this reason, it is better to send | |
12510 | bug reports to the mailing list. | |
12511 | ||
12512 | As a last resort, send bug reports on paper to: | |
12513 | ||
12514 | @example | |
12515 | @sc{gnu} Debugger Bugs | |
12516 | Free Software Foundation Inc. | |
12517 | 59 Temple Place - Suite 330 | |
12518 | Boston, MA 02111-1307 | |
12519 | USA | |
12520 | @end example | |
c906108c SS |
12521 | |
12522 | The fundamental principle of reporting bugs usefully is this: | |
12523 | @strong{report all the facts}. If you are not sure whether to state a | |
12524 | fact or leave it out, state it! | |
12525 | ||
12526 | Often people omit facts because they think they know what causes the | |
12527 | problem and assume that some details do not matter. Thus, you might | |
12528 | assume that the name of the variable you use in an example does not matter. | |
12529 | Well, probably it does not, but one cannot be sure. Perhaps the bug is a | |
12530 | stray memory reference which happens to fetch from the location where that | |
12531 | name is stored in memory; perhaps, if the name were different, the contents | |
12532 | of that location would fool the debugger into doing the right thing despite | |
12533 | the bug. Play it safe and give a specific, complete example. That is the | |
12534 | easiest thing for you to do, and the most helpful. | |
12535 | ||
12536 | Keep in mind that the purpose of a bug report is to enable us to fix the | |
12537 | bug. It may be that the bug has been reported previously, but neither | |
12538 | you nor we can know that unless your bug report is complete and | |
12539 | self-contained. | |
12540 | ||
12541 | Sometimes people give a few sketchy facts and ask, ``Does this ring a | |
12542 | bell?'' Those bug reports are useless, and we urge everyone to | |
12543 | @emph{refuse to respond to them} except to chide the sender to report | |
12544 | bugs properly. | |
12545 | ||
12546 | To enable us to fix the bug, you should include all these things: | |
12547 | ||
12548 | @itemize @bullet | |
12549 | @item | |
12550 | The version of @value{GDBN}. @value{GDBN} announces it if you start | |
12551 | with no arguments; you can also print it at any time using @code{show | |
12552 | version}. | |
12553 | ||
12554 | Without this, we will not know whether there is any point in looking for | |
12555 | the bug in the current version of @value{GDBN}. | |
12556 | ||
12557 | @item | |
12558 | The type of machine you are using, and the operating system name and | |
12559 | version number. | |
12560 | ||
c906108c SS |
12561 | @item |
12562 | What compiler (and its version) was used to compile @value{GDBN}---e.g. | |
12563 | ``@value{GCC}--2.8.1''. | |
c906108c SS |
12564 | |
12565 | @item | |
12566 | What compiler (and its version) was used to compile the program you are | |
12567 | debugging---e.g. ``@value{GCC}--2.8.1'', or ``HP92453-01 A.10.32.03 HP | |
12568 | C Compiler''. For GCC, you can say @code{gcc --version} to get this | |
12569 | information; for other compilers, see the documentation for those | |
12570 | compilers. | |
12571 | ||
12572 | @item | |
12573 | The command arguments you gave the compiler to compile your example and | |
12574 | observe the bug. For example, did you use @samp{-O}? To guarantee | |
12575 | you will not omit something important, list them all. A copy of the | |
12576 | Makefile (or the output from make) is sufficient. | |
12577 | ||
12578 | If we were to try to guess the arguments, we would probably guess wrong | |
12579 | and then we might not encounter the bug. | |
12580 | ||
12581 | @item | |
12582 | A complete input script, and all necessary source files, that will | |
12583 | reproduce the bug. | |
12584 | ||
12585 | @item | |
12586 | A description of what behavior you observe that you believe is | |
12587 | incorrect. For example, ``It gets a fatal signal.'' | |
12588 | ||
12589 | Of course, if the bug is that @value{GDBN} gets a fatal signal, then we | |
12590 | will certainly notice it. But if the bug is incorrect output, we might | |
12591 | not notice unless it is glaringly wrong. You might as well not give us | |
12592 | a chance to make a mistake. | |
12593 | ||
12594 | Even if the problem you experience is a fatal signal, you should still | |
12595 | say so explicitly. Suppose something strange is going on, such as, your | |
12596 | copy of @value{GDBN} is out of synch, or you have encountered a bug in | |
12597 | the C library on your system. (This has happened!) Your copy might | |
12598 | crash and ours would not. If you told us to expect a crash, then when | |
12599 | ours fails to crash, we would know that the bug was not happening for | |
12600 | us. If you had not told us to expect a crash, then we would not be able | |
12601 | to draw any conclusion from our observations. | |
12602 | ||
c906108c SS |
12603 | @item |
12604 | If you wish to suggest changes to the @value{GDBN} source, send us context | |
12605 | diffs. If you even discuss something in the @value{GDBN} source, refer to | |
12606 | it by context, not by line number. | |
12607 | ||
12608 | The line numbers in our development sources will not match those in your | |
12609 | sources. Your line numbers would convey no useful information to us. | |
53a5351d | 12610 | |
c906108c SS |
12611 | @end itemize |
12612 | ||
12613 | Here are some things that are not necessary: | |
12614 | ||
12615 | @itemize @bullet | |
12616 | @item | |
12617 | A description of the envelope of the bug. | |
12618 | ||
12619 | Often people who encounter a bug spend a lot of time investigating | |
12620 | which changes to the input file will make the bug go away and which | |
12621 | changes will not affect it. | |
12622 | ||
12623 | This is often time consuming and not very useful, because the way we | |
12624 | will find the bug is by running a single example under the debugger | |
12625 | with breakpoints, not by pure deduction from a series of examples. | |
12626 | We recommend that you save your time for something else. | |
12627 | ||
12628 | Of course, if you can find a simpler example to report @emph{instead} | |
12629 | of the original one, that is a convenience for us. Errors in the | |
12630 | output will be easier to spot, running under the debugger will take | |
12631 | less time, and so on. | |
12632 | ||
12633 | However, simplification is not vital; if you do not want to do this, | |
12634 | report the bug anyway and send us the entire test case you used. | |
12635 | ||
12636 | @item | |
12637 | A patch for the bug. | |
12638 | ||
12639 | A patch for the bug does help us if it is a good one. But do not omit | |
12640 | the necessary information, such as the test case, on the assumption that | |
12641 | a patch is all we need. We might see problems with your patch and decide | |
12642 | to fix the problem another way, or we might not understand it at all. | |
12643 | ||
12644 | Sometimes with a program as complicated as @value{GDBN} it is very hard to | |
12645 | construct an example that will make the program follow a certain path | |
12646 | through the code. If you do not send us the example, we will not be able | |
12647 | to construct one, so we will not be able to verify that the bug is fixed. | |
12648 | ||
12649 | And if we cannot understand what bug you are trying to fix, or why your | |
12650 | patch should be an improvement, we will not install it. A test case will | |
12651 | help us to understand. | |
12652 | ||
12653 | @item | |
12654 | A guess about what the bug is or what it depends on. | |
12655 | ||
12656 | Such guesses are usually wrong. Even we cannot guess right about such | |
12657 | things without first using the debugger to find the facts. | |
12658 | @end itemize | |
12659 | ||
5d161b24 | 12660 | @c The readline documentation is distributed with the readline code |
c906108c SS |
12661 | @c and consists of the two following files: |
12662 | @c rluser.texinfo | |
7be570e7 | 12663 | @c inc-hist.texinfo |
c906108c SS |
12664 | @c Use -I with makeinfo to point to the appropriate directory, |
12665 | @c environment var TEXINPUTS with TeX. | |
12666 | @include rluser.texinfo | |
7be570e7 | 12667 | @include inc-hist.texinfo |
c906108c SS |
12668 | |
12669 | ||
6d2ebf8b | 12670 | @node Formatting Documentation |
c906108c SS |
12671 | @appendix Formatting Documentation |
12672 | ||
12673 | @cindex @value{GDBN} reference card | |
12674 | @cindex reference card | |
12675 | The @value{GDBN} 4 release includes an already-formatted reference card, ready | |
12676 | for printing with PostScript or Ghostscript, in the @file{gdb} | |
12677 | subdirectory of the main source directory@footnote{In | |
12678 | @file{gdb-@value{GDBVN}/gdb/refcard.ps} of the version @value{GDBVN} | |
12679 | release.}. If you can use PostScript or Ghostscript with your printer, | |
12680 | you can print the reference card immediately with @file{refcard.ps}. | |
12681 | ||
12682 | The release also includes the source for the reference card. You | |
12683 | can format it, using @TeX{}, by typing: | |
12684 | ||
12685 | @example | |
12686 | make refcard.dvi | |
12687 | @end example | |
12688 | ||
5d161b24 DB |
12689 | The @value{GDBN} reference card is designed to print in @dfn{landscape} |
12690 | mode on US ``letter'' size paper; | |
c906108c SS |
12691 | that is, on a sheet 11 inches wide by 8.5 inches |
12692 | high. You will need to specify this form of printing as an option to | |
12693 | your @sc{dvi} output program. | |
12694 | ||
12695 | @cindex documentation | |
12696 | ||
12697 | All the documentation for @value{GDBN} comes as part of the machine-readable | |
12698 | distribution. The documentation is written in Texinfo format, which is | |
12699 | a documentation system that uses a single source file to produce both | |
12700 | on-line information and a printed manual. You can use one of the Info | |
12701 | formatting commands to create the on-line version of the documentation | |
12702 | and @TeX{} (or @code{texi2roff}) to typeset the printed version. | |
12703 | ||
12704 | @value{GDBN} includes an already formatted copy of the on-line Info | |
12705 | version of this manual in the @file{gdb} subdirectory. The main Info | |
12706 | file is @file{gdb-@value{GDBVN}/gdb/gdb.info}, and it refers to | |
12707 | subordinate files matching @samp{gdb.info*} in the same directory. If | |
12708 | necessary, you can print out these files, or read them with any editor; | |
12709 | but they are easier to read using the @code{info} subsystem in @sc{gnu} | |
12710 | Emacs or the standalone @code{info} program, available as part of the | |
12711 | @sc{gnu} Texinfo distribution. | |
12712 | ||
12713 | If you want to format these Info files yourself, you need one of the | |
12714 | Info formatting programs, such as @code{texinfo-format-buffer} or | |
12715 | @code{makeinfo}. | |
12716 | ||
12717 | If you have @code{makeinfo} installed, and are in the top level | |
12718 | @value{GDBN} source directory (@file{gdb-@value{GDBVN}}, in the case of | |
12719 | version @value{GDBVN}), you can make the Info file by typing: | |
12720 | ||
12721 | @example | |
12722 | cd gdb | |
12723 | make gdb.info | |
12724 | @end example | |
12725 | ||
12726 | If you want to typeset and print copies of this manual, you need @TeX{}, | |
12727 | a program to print its @sc{dvi} output files, and @file{texinfo.tex}, the | |
12728 | Texinfo definitions file. | |
12729 | ||
12730 | @TeX{} is a typesetting program; it does not print files directly, but | |
12731 | produces output files called @sc{dvi} files. To print a typeset | |
12732 | document, you need a program to print @sc{dvi} files. If your system | |
12733 | has @TeX{} installed, chances are it has such a program. The precise | |
12734 | command to use depends on your system; @kbd{lpr -d} is common; another | |
12735 | (for PostScript devices) is @kbd{dvips}. The @sc{dvi} print command may | |
12736 | require a file name without any extension or a @samp{.dvi} extension. | |
12737 | ||
12738 | @TeX{} also requires a macro definitions file called | |
12739 | @file{texinfo.tex}. This file tells @TeX{} how to typeset a document | |
12740 | written in Texinfo format. On its own, @TeX{} cannot either read or | |
12741 | typeset a Texinfo file. @file{texinfo.tex} is distributed with GDB | |
12742 | and is located in the @file{gdb-@var{version-number}/texinfo} | |
12743 | directory. | |
12744 | ||
12745 | If you have @TeX{} and a @sc{dvi} printer program installed, you can | |
12746 | typeset and print this manual. First switch to the the @file{gdb} | |
12747 | subdirectory of the main source directory (for example, to | |
12748 | @file{gdb-@value{GDBVN}/gdb}) and type: | |
12749 | ||
12750 | @example | |
12751 | make gdb.dvi | |
12752 | @end example | |
12753 | ||
12754 | Then give @file{gdb.dvi} to your @sc{dvi} printing program. | |
c906108c | 12755 | |
6d2ebf8b | 12756 | @node Installing GDB |
c906108c SS |
12757 | @appendix Installing @value{GDBN} |
12758 | @cindex configuring @value{GDBN} | |
12759 | @cindex installation | |
12760 | ||
c906108c SS |
12761 | @value{GDBN} comes with a @code{configure} script that automates the process |
12762 | of preparing @value{GDBN} for installation; you can then use @code{make} to | |
12763 | build the @code{gdb} program. | |
12764 | @iftex | |
12765 | @c irrelevant in info file; it's as current as the code it lives with. | |
12766 | @footnote{If you have a more recent version of @value{GDBN} than @value{GDBVN}, | |
12767 | look at the @file{README} file in the sources; we may have improved the | |
12768 | installation procedures since publishing this manual.} | |
12769 | @end iftex | |
12770 | ||
5d161b24 DB |
12771 | The @value{GDBN} distribution includes all the source code you need for |
12772 | @value{GDBN} in a single directory, whose name is usually composed by | |
c906108c SS |
12773 | appending the version number to @samp{gdb}. |
12774 | ||
12775 | For example, the @value{GDBN} version @value{GDBVN} distribution is in the | |
12776 | @file{gdb-@value{GDBVN}} directory. That directory contains: | |
12777 | ||
12778 | @table @code | |
12779 | @item gdb-@value{GDBVN}/configure @r{(and supporting files)} | |
12780 | script for configuring @value{GDBN} and all its supporting libraries | |
12781 | ||
12782 | @item gdb-@value{GDBVN}/gdb | |
12783 | the source specific to @value{GDBN} itself | |
12784 | ||
12785 | @item gdb-@value{GDBVN}/bfd | |
12786 | source for the Binary File Descriptor library | |
12787 | ||
12788 | @item gdb-@value{GDBVN}/include | |
12789 | @sc{gnu} include files | |
12790 | ||
12791 | @item gdb-@value{GDBVN}/libiberty | |
12792 | source for the @samp{-liberty} free software library | |
12793 | ||
12794 | @item gdb-@value{GDBVN}/opcodes | |
12795 | source for the library of opcode tables and disassemblers | |
12796 | ||
12797 | @item gdb-@value{GDBVN}/readline | |
12798 | source for the @sc{gnu} command-line interface | |
12799 | ||
12800 | @item gdb-@value{GDBVN}/glob | |
12801 | source for the @sc{gnu} filename pattern-matching subroutine | |
12802 | ||
12803 | @item gdb-@value{GDBVN}/mmalloc | |
12804 | source for the @sc{gnu} memory-mapped malloc package | |
12805 | @end table | |
12806 | ||
12807 | The simplest way to configure and build @value{GDBN} is to run @code{configure} | |
12808 | from the @file{gdb-@var{version-number}} source directory, which in | |
12809 | this example is the @file{gdb-@value{GDBVN}} directory. | |
12810 | ||
12811 | First switch to the @file{gdb-@var{version-number}} source directory | |
12812 | if you are not already in it; then run @code{configure}. Pass the | |
12813 | identifier for the platform on which @value{GDBN} will run as an | |
12814 | argument. | |
12815 | ||
12816 | For example: | |
12817 | ||
12818 | @example | |
12819 | cd gdb-@value{GDBVN} | |
12820 | ./configure @var{host} | |
12821 | make | |
12822 | @end example | |
12823 | ||
12824 | @noindent | |
12825 | where @var{host} is an identifier such as @samp{sun4} or | |
12826 | @samp{decstation}, that identifies the platform where @value{GDBN} will run. | |
12827 | (You can often leave off @var{host}; @code{configure} tries to guess the | |
12828 | correct value by examining your system.) | |
12829 | ||
12830 | Running @samp{configure @var{host}} and then running @code{make} builds the | |
12831 | @file{bfd}, @file{readline}, @file{mmalloc}, and @file{libiberty} | |
12832 | libraries, then @code{gdb} itself. The configured source files, and the | |
12833 | binaries, are left in the corresponding source directories. | |
12834 | ||
12835 | @need 750 | |
12836 | @code{configure} is a Bourne-shell (@code{/bin/sh}) script; if your | |
12837 | system does not recognize this automatically when you run a different | |
12838 | shell, you may need to run @code{sh} on it explicitly: | |
12839 | ||
12840 | @example | |
12841 | sh configure @var{host} | |
12842 | @end example | |
12843 | ||
12844 | If you run @code{configure} from a directory that contains source | |
12845 | directories for multiple libraries or programs, such as the | |
12846 | @file{gdb-@value{GDBVN}} source directory for version @value{GDBVN}, @code{configure} | |
12847 | creates configuration files for every directory level underneath (unless | |
12848 | you tell it not to, with the @samp{--norecursion} option). | |
12849 | ||
12850 | You can run the @code{configure} script from any of the | |
12851 | subordinate directories in the @value{GDBN} distribution if you only want to | |
12852 | configure that subdirectory, but be sure to specify a path to it. | |
12853 | ||
12854 | For example, with version @value{GDBVN}, type the following to configure only | |
12855 | the @code{bfd} subdirectory: | |
12856 | ||
12857 | @example | |
12858 | @group | |
12859 | cd gdb-@value{GDBVN}/bfd | |
12860 | ../configure @var{host} | |
12861 | @end group | |
12862 | @end example | |
12863 | ||
12864 | You can install @code{@value{GDBP}} anywhere; it has no hardwired paths. | |
12865 | However, you should make sure that the shell on your path (named by | |
12866 | the @samp{SHELL} environment variable) is publicly readable. Remember | |
12867 | that @value{GDBN} uses the shell to start your program---some systems refuse to | |
12868 | let @value{GDBN} debug child processes whose programs are not readable. | |
12869 | ||
12870 | @menu | |
12871 | * Separate Objdir:: Compiling @value{GDBN} in another directory | |
12872 | * Config Names:: Specifying names for hosts and targets | |
12873 | * Configure Options:: Summary of options for configure | |
12874 | @end menu | |
12875 | ||
6d2ebf8b | 12876 | @node Separate Objdir |
c906108c SS |
12877 | @section Compiling @value{GDBN} in another directory |
12878 | ||
12879 | If you want to run @value{GDBN} versions for several host or target machines, | |
12880 | you need a different @code{gdb} compiled for each combination of | |
12881 | host and target. @code{configure} is designed to make this easy by | |
12882 | allowing you to generate each configuration in a separate subdirectory, | |
12883 | rather than in the source directory. If your @code{make} program | |
12884 | handles the @samp{VPATH} feature (@sc{gnu} @code{make} does), running | |
12885 | @code{make} in each of these directories builds the @code{gdb} | |
12886 | program specified there. | |
12887 | ||
12888 | To build @code{gdb} in a separate directory, run @code{configure} | |
12889 | with the @samp{--srcdir} option to specify where to find the source. | |
12890 | (You also need to specify a path to find @code{configure} | |
12891 | itself from your working directory. If the path to @code{configure} | |
12892 | would be the same as the argument to @samp{--srcdir}, you can leave out | |
12893 | the @samp{--srcdir} option; it is assumed.) | |
12894 | ||
5d161b24 | 12895 | For example, with version @value{GDBVN}, you can build @value{GDBN} in a |
c906108c SS |
12896 | separate directory for a Sun 4 like this: |
12897 | ||
12898 | @example | |
12899 | @group | |
12900 | cd gdb-@value{GDBVN} | |
12901 | mkdir ../gdb-sun4 | |
12902 | cd ../gdb-sun4 | |
12903 | ../gdb-@value{GDBVN}/configure sun4 | |
12904 | make | |
12905 | @end group | |
12906 | @end example | |
12907 | ||
12908 | When @code{configure} builds a configuration using a remote source | |
12909 | directory, it creates a tree for the binaries with the same structure | |
12910 | (and using the same names) as the tree under the source directory. In | |
12911 | the example, you'd find the Sun 4 library @file{libiberty.a} in the | |
12912 | directory @file{gdb-sun4/libiberty}, and @value{GDBN} itself in | |
12913 | @file{gdb-sun4/gdb}. | |
12914 | ||
12915 | One popular reason to build several @value{GDBN} configurations in separate | |
5d161b24 DB |
12916 | directories is to configure @value{GDBN} for cross-compiling (where |
12917 | @value{GDBN} runs on one machine---the @dfn{host}---while debugging | |
12918 | programs that run on another machine---the @dfn{target}). | |
c906108c SS |
12919 | You specify a cross-debugging target by |
12920 | giving the @samp{--target=@var{target}} option to @code{configure}. | |
12921 | ||
12922 | When you run @code{make} to build a program or library, you must run | |
12923 | it in a configured directory---whatever directory you were in when you | |
12924 | called @code{configure} (or one of its subdirectories). | |
12925 | ||
12926 | The @code{Makefile} that @code{configure} generates in each source | |
12927 | directory also runs recursively. If you type @code{make} in a source | |
12928 | directory such as @file{gdb-@value{GDBVN}} (or in a separate configured | |
12929 | directory configured with @samp{--srcdir=@var{dirname}/gdb-@value{GDBVN}}), you | |
12930 | will build all the required libraries, and then build GDB. | |
12931 | ||
12932 | When you have multiple hosts or targets configured in separate | |
12933 | directories, you can run @code{make} on them in parallel (for example, | |
12934 | if they are NFS-mounted on each of the hosts); they will not interfere | |
12935 | with each other. | |
12936 | ||
6d2ebf8b | 12937 | @node Config Names |
c906108c SS |
12938 | @section Specifying names for hosts and targets |
12939 | ||
12940 | The specifications used for hosts and targets in the @code{configure} | |
12941 | script are based on a three-part naming scheme, but some short predefined | |
12942 | aliases are also supported. The full naming scheme encodes three pieces | |
12943 | of information in the following pattern: | |
12944 | ||
12945 | @example | |
12946 | @var{architecture}-@var{vendor}-@var{os} | |
12947 | @end example | |
12948 | ||
12949 | For example, you can use the alias @code{sun4} as a @var{host} argument, | |
12950 | or as the value for @var{target} in a @code{--target=@var{target}} | |
12951 | option. The equivalent full name is @samp{sparc-sun-sunos4}. | |
12952 | ||
12953 | The @code{configure} script accompanying @value{GDBN} does not provide | |
12954 | any query facility to list all supported host and target names or | |
12955 | aliases. @code{configure} calls the Bourne shell script | |
12956 | @code{config.sub} to map abbreviations to full names; you can read the | |
12957 | script, if you wish, or you can use it to test your guesses on | |
12958 | abbreviations---for example: | |
12959 | ||
12960 | @smallexample | |
12961 | % sh config.sub i386-linux | |
12962 | i386-pc-linux-gnu | |
12963 | % sh config.sub alpha-linux | |
12964 | alpha-unknown-linux-gnu | |
12965 | % sh config.sub hp9k700 | |
12966 | hppa1.1-hp-hpux | |
12967 | % sh config.sub sun4 | |
12968 | sparc-sun-sunos4.1.1 | |
12969 | % sh config.sub sun3 | |
12970 | m68k-sun-sunos4.1.1 | |
12971 | % sh config.sub i986v | |
12972 | Invalid configuration `i986v': machine `i986v' not recognized | |
12973 | @end smallexample | |
12974 | ||
12975 | @noindent | |
12976 | @code{config.sub} is also distributed in the @value{GDBN} source | |
12977 | directory (@file{gdb-@value{GDBVN}}, for version @value{GDBVN}). | |
12978 | ||
6d2ebf8b | 12979 | @node Configure Options |
c906108c SS |
12980 | @section @code{configure} options |
12981 | ||
12982 | Here is a summary of the @code{configure} options and arguments that | |
12983 | are most often useful for building @value{GDBN}. @code{configure} also has | |
12984 | several other options not listed here. @inforef{What Configure | |
12985 | Does,,configure.info}, for a full explanation of @code{configure}. | |
12986 | ||
12987 | @example | |
12988 | configure @r{[}--help@r{]} | |
12989 | @r{[}--prefix=@var{dir}@r{]} | |
12990 | @r{[}--exec-prefix=@var{dir}@r{]} | |
12991 | @r{[}--srcdir=@var{dirname}@r{]} | |
12992 | @r{[}--norecursion@r{]} @r{[}--rm@r{]} | |
12993 | @r{[}--target=@var{target}@r{]} | |
12994 | @var{host} | |
12995 | @end example | |
12996 | ||
12997 | @noindent | |
12998 | You may introduce options with a single @samp{-} rather than | |
12999 | @samp{--} if you prefer; but you may abbreviate option names if you use | |
13000 | @samp{--}. | |
13001 | ||
13002 | @table @code | |
13003 | @item --help | |
13004 | Display a quick summary of how to invoke @code{configure}. | |
13005 | ||
13006 | @item --prefix=@var{dir} | |
13007 | Configure the source to install programs and files under directory | |
13008 | @file{@var{dir}}. | |
13009 | ||
13010 | @item --exec-prefix=@var{dir} | |
13011 | Configure the source to install programs under directory | |
13012 | @file{@var{dir}}. | |
13013 | ||
13014 | @c avoid splitting the warning from the explanation: | |
13015 | @need 2000 | |
13016 | @item --srcdir=@var{dirname} | |
13017 | @strong{Warning: using this option requires @sc{gnu} @code{make}, or another | |
13018 | @code{make} that implements the @code{VPATH} feature.}@* | |
13019 | Use this option to make configurations in directories separate from the | |
13020 | @value{GDBN} source directories. Among other things, you can use this to | |
13021 | build (or maintain) several configurations simultaneously, in separate | |
13022 | directories. @code{configure} writes configuration specific files in | |
13023 | the current directory, but arranges for them to use the source in the | |
13024 | directory @var{dirname}. @code{configure} creates directories under | |
13025 | the working directory in parallel to the source directories below | |
13026 | @var{dirname}. | |
13027 | ||
13028 | @item --norecursion | |
13029 | Configure only the directory level where @code{configure} is executed; do not | |
13030 | propagate configuration to subdirectories. | |
13031 | ||
13032 | @item --target=@var{target} | |
13033 | Configure @value{GDBN} for cross-debugging programs running on the specified | |
13034 | @var{target}. Without this option, @value{GDBN} is configured to debug | |
13035 | programs that run on the same machine (@var{host}) as @value{GDBN} itself. | |
13036 | ||
13037 | There is no convenient way to generate a list of all available targets. | |
13038 | ||
13039 | @item @var{host} @dots{} | |
13040 | Configure @value{GDBN} to run on the specified @var{host}. | |
13041 | ||
13042 | There is no convenient way to generate a list of all available hosts. | |
13043 | @end table | |
13044 | ||
13045 | There are many other options available as well, but they are generally | |
13046 | needed for special purposes only. | |
5d161b24 | 13047 | |
6d2ebf8b | 13048 | @node Index |
c906108c SS |
13049 | @unnumbered Index |
13050 | ||
13051 | @printindex cp | |
13052 | ||
13053 | @tex | |
13054 | % I think something like @colophon should be in texinfo. In the | |
13055 | % meantime: | |
13056 | \long\def\colophon{\hbox to0pt{}\vfill | |
13057 | \centerline{The body of this manual is set in} | |
13058 | \centerline{\fontname\tenrm,} | |
13059 | \centerline{with headings in {\bf\fontname\tenbf}} | |
13060 | \centerline{and examples in {\tt\fontname\tentt}.} | |
13061 | \centerline{{\it\fontname\tenit\/},} | |
13062 | \centerline{{\bf\fontname\tenbf}, and} | |
13063 | \centerline{{\sl\fontname\tensl\/}} | |
13064 | \centerline{are used for emphasis.}\vfill} | |
13065 | \page\colophon | |
13066 | % Blame: [email protected], 1991. | |
13067 | @end tex | |
13068 | ||
449f3b6c AC |
13069 | @c TeX can handle the contents at the start but makeinfo 3.12 can not |
13070 | @ifinfo | |
c906108c | 13071 | @contents |
449f3b6c AC |
13072 | @end ifinfo |
13073 | @ifhtml | |
13074 | @contents | |
13075 | @end ifhtml | |
13076 | ||
c906108c | 13077 | @bye |