@ifinfo
@format
START-INFO-DIR-ENTRY
-* Gdb-Internals: (gdbint). The GNU debugger internals.
+* Gdb-Internals: (gdbint). The GNU debugger's internals.
END-INFO-DIR-ENTRY
@end format
@end ifinfo
@ifinfo
This file documents the internals of the GNU debugger GDB.
-Copyright (C) 1990, 1991, 1992 Free Software Foundation, Inc.
+Copyright 1990, 1991, 1992, 1993 Free Software Foundation, Inc.
Contributed by Cygnus Support. Written by John Gilmore.
Permission is granted to make and distribute verbatim copies of
@end tex
@vskip 0pt plus 1filll
-Copyright @copyright{} 1990, 1991, 1992 Free Software Foundation, Inc.
+Copyright @copyright{} 1990, 1991, 1992, 1993 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
@end titlepage
-@node Top, README, (dir), (dir)
-
-This file documents the internals of the GNU debugger GDB. It is a
+@node Top
+@top
+This documents the internals of the GNU debugger, GDB. It is a
collection of miscellaneous information with little form at this point.
Mostly, it is a repository into which you can put information about
GDB as you discover it (or as you design changes to GDB).
* New Architectures:: Defining a New Host or Target Architecture
* Config:: Adding a New Configuration
* Host:: Adding a New Host
+* Native:: Adding a New Native Configuration
* Target:: Adding a New Target
* Languages:: Defining New Source Languages
* Releases:: Configuring GDB for Release
* Partial Symbol Tables:: How GDB reads symbols quickly at startup
+* Types:: How GDB keeps track of types
* BFD support for GDB:: How BFD and GDB interface
* Symbol Reading:: Defining New Symbol Readers
* Cleanups:: Cleanups
* Wrapping:: Wrapping Output Lines
-* Frames:: Keeping track of function calls
-* Host Conditionals:: Controlling what features exist in the host
-* Target Conditionals:: Controlling what features exist in the target
-
+* Frames:: Keeping track of function calls
+* Remote Stubs:: Code that runs in targets and talks to GDB
+* Longjmp Support:: Stepping through longjmp's in the target
+* Coding Style:: Strunk and White for GDB maintainers
+* Clean Design:: Frank Lloyd Wright for GDB maintainers
+* Submitting Patches:: How to get your changes into GDB releases
+* Host Conditionals:: What features exist in the host
+* Target Conditionals:: What features exist in the target
+* Native Conditionals:: Conditionals for when host and target are same
+* Obsolete Conditionals:: Conditionals that don't exist any more
+* XCOFF:: The Object file format used on IBM's RS/6000
@end menu
-@node README, New Architectures, Top, Top
+@node README
@chapter The @file{README} File
Check the @file{README} file, it often has useful information that does not
appear anywhere else in the directory.
-@node New Architectures, Config, README, Top
+@node New Architectures
@chapter Defining a New Host or Target Architecture
When building support for a new host and/or target, much of the work you
@dfn{Host} refers to attributes of the system where GDB runs.
@dfn{Target} refers to the system where the program being debugged
-executes. In most cases they are the same machine; unfortunately, that
-means you must add @emph{both} host and target support for new machines
-in this category.
-
-The @file{config/mh-*}, @file{xm-*.h} and @file{*-xdep.c} files are for
-host support. Similarly, the @file{config/mt-*}, @file{tm-*.h} and
-@file{*-tdep.c} files are for target support. The question is, what
-features or aspects of a debugging or cross-debugging environment are
-considered to be ``host'' support?
+executes. In most cases they are the same machine, in which case
+a third type of @dfn{Native} attributes come into play.
Defines and include files needed to build on the host are host support.
Examples are tty support, system defined types, host byte order, host
float format.
-Unix child process support is considered an aspect of the host. Since
-when you fork on the host you are still on the host, the various macros
-needed for finding the registers in the upage, running @code{ptrace}, and such
-are all in the host-dependent files.
+Defines and information needed to handle the target format are target
+dependent. Examples are the stack frame format, instruction set,
+breakpoint instruction, registers, and how to set up and tear down the stack
+to call a function.
+
+Information that is only needed when the host and target are the same,
+is native dependent. One example is Unix child process support; if the
+host and target are not the same, doing a fork to start the target
+process is a bad idea. The various macros needed for finding the
+registers in the @code{upage}, running @code{ptrace}, and such are all in the
+native-dependent files.
-@c FIXME so what kinds of things are target support?
+Another example of native-dependent code is support for features
+that are really part of the target environment, but which require
+@code{#include} files that are only available on the host system.
+Core file handling and @code{setjmp} handling are two common cases.
-This is still somewhat of a grey area; I (John Gilmore) didn't do the
-@file{xm-*} and @file{tm-*} split for gdb (it was done by Jim Kingdon)
-so I have had to figure out the grounds on which it was split, and make
-my own choices as I evolve it. I have moved many things out of the xdep
-files actually, partly as a result of BFD and partly by removing
-duplicated code.
+When you want to make GDB work ``native'' on a particular
+machine, you have to include all three kinds of information.
+The dependent information in GDB is organized into files by naming
+conventions.
-@node Config, Host, New Architectures, Top
+Host-Dependent Files
+@table @file
+@item config/*/*.mh
+Sets Makefile parameters
+@item config/*/xm-*.h
+Global #include's and #define's and definitions
+@item *-xdep.c
+Global variables and functions
+@end table
+
+Native-Dependent Files
+@table @file
+@item config/*/*.mh
+Sets Makefile parameters (for @emph{both} host and native)
+@item config/*/nm-*.h
+#include's and #define's and definitions. This file
+is only included by the small number of modules that need it,
+so beware of doing feature-test #define's from its macros.
+@item *-nat.c
+global variables and functions
+@end table
+
+Target-Dependent Files
+@table @file
+@item config/*/*.mt
+Sets Makefile parameters
+@item config/*/tm-*.h
+Global #include's and #define's and definitions
+@item *-tdep.c
+Global variables and functions
+@end table
+
+At this writing, most supported hosts have had their host and native
+dependencies sorted out properly. There are a few stragglers, which
+can be recognized by the absence of NATDEPFILES lines in their
+@file{config/*/*.mh}.
+
+@node Config
@chapter Adding a New Configuration
Most of the work in making GDB compile on a new machine is in specifying
create a new file @file{bfd/hosts/h-@var{xxx}.h}. Examine the
other @file{h-*.h} files as templates, and create one that brings in the
right include files for your system, and defines any host-specific
-macros needed by GDB.
+macros needed by BFD, the Binutils, GNU LD, or the Opcodes directories.
+(They all share the bfd @file{hosts} directory and the @file{configure.host}
+file.)
-Then edit @file{bfd/configure.in}. Add shell script code to recognize your
+Then edit @file{bfd/configure.host}. Add a line to recognize your
@code{@var{xarch}-@var{xvend}-@var{xos}} configuration, and set
@code{my_host} to @var{xxx} when you recognize it. This will cause your
file @file{h-@var{xxx}.h} to be linked to @file{sysdep.h} at configuration
-time.
+time. When creating the line that recognizes your configuration,
+only match the fields that you really need to match; e.g. don't match
+match the architecture or manufacturer if the OS is sufficient
+to distinguish the configuration that your @file{h-@var{xxx}.h} file supports.
+Don't match the manufacturer name unless you really need to.
+This should make future ports easier.
Also, if this host requires any changes to the Makefile, create a file
-@file{bfd/config/mh-@var{xxx}}, which includes the required lines.
-
-(If you have the binary utilities and/or GNU ld in the same tree,
-you'll also have to edit @file{binutils/configure.in} or
-@file{ld/configure.in} to match what you've done in the @file{bfd}
-directory.)
+@file{bfd/config/@var{xxx}.mh}, which includes the required lines.
It's possible that the @file{libiberty} and @file{readline} directories
won't need any changes for your configuration, but if they do, you can
map to an @file{mh-@var{xxx}} file. Then add @file{mh-@var{xxx}}
to the @file{config/} subdirectory, to set any makefile variables you
need. The only current options in there are things like @samp{-DSYSV}.
+(This @file{mh-@var{xxx}} naming convention differs from elsewhere
+in GDB, by historical accident. It should be cleaned up so that all
+such files are called @file{@var{xxx}.mh}.)
Aha! Now to configure GDB itself! Edit
@file{gdb/configure.in} to recognize your system and set @code{gdb_host}
@c Would it be simpler to just use different per-host and per-target
@c *scripts*, and call them from {configure} ?
-Finally, you'll need to specify and define GDB's host- and
+Finally, you'll need to specify and define GDB's host-, native-, and
target-dependent @file{.h} and @file{.c} files used for your
configuration; the next two chapters discuss those.
-@node Host, Target, Config, Top
+@node Host
@chapter Adding a New Host
Once you have specified a new configuration for your host
-(@pxref{Config,,Adding a New Configuration}), there are two remaining
+(@pxref{Config,,Adding a New Configuration}), there are three remaining
pieces to making GDB work on a new machine. First, you have to make it
host on the new machine (compile there, handle that machine's terminals
properly, etc). If you will be cross-debugging to some other kind of
If you want to use GDB to debug programs that run on the new machine,
you have to get it to understand the machine's object files, symbol
-files, and interfaces to processes. @pxref{Target,,Adding a New Target}
+files, and interfaces to processes; @pxref{Target,,Adding a New Target}
+and @pxref{Native,,Adding a New Native Configuration}
Several files control GDB's configuration for host systems:
@table @file
-@item gdb/config/mh-@var{xxx}
+@item gdb/config/@var{arch}/@var{xxx}.mh
Specifies Makefile fragments needed when hosting on machine @var{xxx}.
In particular, this lists the required machine-dependent object files,
by defining @samp{XDEPFILES=@dots{}}. Also
@samp{XM_ADD_FILES}, @samp{XM_CLIBS}, @samp{XM_CDEPS},
etc.; see @file{Makefile.in}.
-@item gdb/xm-@var{xxx}.h
+@item gdb/config/@var{arch}/xm-@var{xxx}.h
(@file{xm.h} is a link to this file, created by configure).
Contains C macro definitions describing the host system environment,
such as byte order, host C compiler and library, ptrace support,
@item gdb/@var{xxx}-xdep.c
Contains any miscellaneous C code required for this machine
-as a host. On some machines it doesn't exist at all.
+as a host. On many machines it doesn't exist at all. If it does
+exist, put @file{@var{xxx}-xdep.o} into the @code{XDEPFILES} line
+in @file{gdb/config/mh-@var{xxx}}.
@end table
+@subheading Generic Host Support Files
+
There are some ``generic'' versions of routines that can be used by
-various host systems. These can be customized in various ways by macros
+various systems. These can be customized in various ways by macros
defined in your @file{xm-@var{xxx}.h} file. If these routines work for
the @var{xxx} host, you can just include the generic file's name (with
@samp{.o}, not @samp{.c}) in @code{XDEPFILES}.
Otherwise, if your machine needs custom support routines, you will need
to write routines that perform the same functions as the generic file.
Put them into @code{@var{xxx}-xdep.c}, and put @code{@var{xxx}-xdep.o}
-into @code{XDEPFILES}.
+into @code{XDEPFILES}.
-@subheading Generic Host Support Files
+@table @file
+@item ser-bsd.c
+This contains serial line support for Berkeley-derived Unix systems.
+
+@item ser-go32.c
+This contains serial line support for 32-bit programs running under DOS
+using the GO32 execution environment.
+
+@item ser-termios.c
+This contains serial line support for System V-derived Unix systems.
+@end table
+
+Now, you are now ready to try configuring GDB to compile using your system
+as its host. From the top level (above @file{bfd}, @file{gdb}, etc), do:
+
+@example
+./configure @var{xxx} +target=vxworks960
+@end example
+
+This will configure your system to cross-compile for VxWorks on
+the Intel 960, which is probably not what you really want, but it's
+a test case that works at this stage. (You haven't set up to be
+able to debug programs that run @emph{on} @var{xxx} yet.)
+
+If this succeeds, you can try building it all with:
+
+@example
+make
+@end example
+
+Repeat until the program configures, compiles, links, and runs.
+When run, it won't be able to do much (unless you have a VxWorks/960
+board on your network) but you will know that the host support is
+pretty well done.
+
+Good luck! Comments and suggestions about this section are particularly
+welcome; send them to @samp{bug-gdb@@prep.ai.mit.edu}.
+
+@node Native
+@chapter Adding a New Native Configuration
+
+If you are making GDB run native on the @var{xxx} machine, you have
+plenty more work to do. Several files control GDB's configuration for
+native support:
+
+@table @file
+@item gdb/config/@var{xarch}/@var{xxx}.mh
+Specifies Makefile fragments needed when hosting @emph{or native}
+on machine @var{xxx}.
+In particular, this lists the required native-dependent object files,
+by defining @samp{NATDEPFILES=@dots{}}. Also
+specifies the header file which describes native support on @var{xxx},
+by defining @samp{NAT_FILE= nm-@var{xxx}.h}.
+You can also define @samp{NAT_CFLAGS},
+@samp{NAT_ADD_FILES}, @samp{NAT_CLIBS}, @samp{NAT_CDEPS},
+etc.; see @file{Makefile.in}.
+
+@item gdb/config/@var{arch}/nm-@var{xxx}.h
+(@file{nm.h} is a link to this file, created by configure).
+Contains C macro definitions describing the native system environment,
+such as child process control and core file support.
+Crib from existing @file{nm-*.h} files to create a new one.
+
+@item gdb/@var{xxx}-nat.c
+Contains any miscellaneous C code required for this native support
+of this machine. On some machines it doesn't exist at all.
+@end table
+
+@subheading Generic Native Support Files
+
+There are some ``generic'' versions of routines that can be used by
+various systems. These can be customized in various ways by macros
+defined in your @file{nm-@var{xxx}.h} file. If these routines work for
+the @var{xxx} host, you can just include the generic file's name (with
+@samp{.o}, not @samp{.c}) in @code{NATDEPFILES}.
+
+Otherwise, if your machine needs custom support routines, you will need
+to write routines that perform the same functions as the generic file.
+Put them into @code{@var{xxx}-nat.c}, and put @code{@var{xxx}-nat.o}
+into @code{NATDEPFILES}.
@table @file
+@item inftarg.c
+This contains the @emph{target_ops vector} that supports Unix child
+processes on systems which use ptrace and wait to control the child.
+
+@item procfs.c
+This contains the @emph{target_ops vector} that supports Unix child
+processes on systems which use /proc to control the child.
+
+@item fork-child.c
+This does the low-level grunge that uses Unix system calls
+to do a "fork and exec" to start up a child process.
+
@item infptrace.c
This is the low level interface to inferior processes for systems
using the Unix @code{ptrace} call in a vanilla way.
@code{register_addr()}, see below.
Now that BFD is used to read core files, virtually all machines should
use @code{coredep.c}, and should just provide @code{fetch_core_registers} in
-@code{@var{xxx}-xdep.c} (or @code{REGISTER_U_ADDR} in @code{xm-@var{xxx}.h}).
+@code{@var{xxx}-nat.c} (or @code{REGISTER_U_ADDR} in @code{nm-@var{xxx}.h}).
@item coredep.c::register_addr()
-If your @code{xm-@var{xxx}.h} file defines the macro
+If your @code{nm-@var{xxx}.h} file defines the macro
@code{REGISTER_U_ADDR(addr, blockend, regno)}, it should be defined to
set @code{addr} to the offset within the @samp{user}
struct of GDB register number @code{regno}. @code{blockend} is the
the macro in it. If you do not define @code{REGISTER_U_ADDR}, but you
are using the standard @code{fetch_core_registers()}, you will need to
define your own version of @code{register_addr()}, put it into your
-@code{@var{xxx}-xdep.c} file, and be sure @code{@var{xxx}-xdep.o} is in
-the @code{XDEPFILES} list. If you have your own
+@code{@var{xxx}-nat.c} file, and be sure @code{@var{xxx}-nat.o} is in
+the @code{NATDEPFILES} list. If you have your own
@code{fetch_core_registers()}, you may not need a separate
@code{register_addr()}. Many custom @code{fetch_core_registers()}
implementations simply locate the registers themselves.@refill
@end table
-Object files needed when the target system is an @var{xxx} are listed
-in the file @file{config/mt-@var{xxx}}, in the makefile macro
-@samp{TDEPFILES = }@dots{}. The header file that defines the target
-system should be called @file{tm-@var{xxx}.h}, and should be specified
-as the value of @samp{TM_FILE} in @file{config/mt-@var{xxx}}. You can
-also define @samp{TM_CFLAGS}, @samp{TM_CLIBS}, and @samp{TM_CDEPS} in
-there; see @file{Makefile.in}.
-
-Now, you are now ready to try configuring GDB to compile for your system.
-From the top level (above @file{bfd}, @file{gdb}, etc), do:
-
-@example
-./configure @var{xxx} +target=vxworks960
-@end example
-
-This will configure your system to cross-compile for VxWorks on
-the Intel 960, which is probably not what you really want, but it's
-a test case that works at this stage. (You haven't set up to be
-able to debug programs that run @emph{on} @var{xxx} yet.)
-
-If this succeeds, you can try building it all with:
-
-@example
-make
-@end example
-
-Good luck! Comments and suggestions about this section are particularly
-welcome; send them to @samp{bug-gdb@@prep.ai.mit.edu}.
-
-When hosting GDB on a new operating system, to make it possible to debug
+When making GDB run native on a new operating system,
+to make it possible to debug
core files, you will need to either write specific code for parsing your
OS's core files, or customize @file{bfd/trad-core.c}. First, use
whatever @code{#include} files your machine uses to define the struct of
Then back in GDB, you need a matching routine called
@code{fetch_core_registers()}. If you can use the generic one, it's in
-@file{core-dep.c}; if not, it's in your @file{@var{xxx}-xdep.c} file.
+@file{coredep.c}; if not, it's in your @file{@var{xxx}-nat.c} file.
It will be passed a char pointer to the entire ``registers'' segment,
its length, and a zero; or a char pointer to the entire ``regs2''
segment, its length, and a 2. The routine should suck out the supplied
(@xref{New Architectures,,Defining a New Host or Target Architecture},
for more info about this.)
+If your system uses @file{/proc} to control processes, and uses ELF
+format core files, then you may be able to use the same routines
+for reading the registers out of processes and out of core files.
-@node Target, Languages, Host, Top
+@node Target
@chapter Adding a New Target
For a new target called @var{ttt}, first specify the configuration as
A variety of files specify attributes of the GDB target environment:
@table @file
-@item gdb/config/mt-@var{ttt}
+@item gdb/config/@var{arch}/@var{ttt}.mt
Contains a Makefile fragment specific to this target.
Specifies what object files are needed for target @var{ttt}, by
defining @samp{TDEPFILES=@dots{}}.
Also specifies the header file which describes @var{ttt}, by defining
@samp{TM_FILE= tm-@var{ttt}.h}. You can also define @samp{TM_CFLAGS},
+@samp{TM_CLIBS}, @samp{TM_CDEPS},
and other Makefile variables here; see @file{Makefile.in}.
-@item gdb/tm-@var{ttt}.h
+@item gdb/config/@var{arch}/tm-@var{ttt}.h
(@file{tm.h} is a link to this file, created by configure).
Contains macro definitions about the target machine's
registers, stack frame format and instructions.
between the debugger and the assembler, if the GNU assembler has been
ported to the target machine.
-@item gdb/tm-@var{arch}.h
+@item gdb/config/@var{arch}/tm-@var{arch}.h
This often exists to describe the basic layout of the target machine's
processor chip (registers, stack, etc).
If used, it is included by @file{tm-@var{xxx}.h}. It can
there is probably little to be done. See @file{bfd/doc/bfd.texinfo}
for more information on writing new a.out or COFF versions.
-If you need to add a new object file format, you are beyond the scope
-of this document right now. Look at the structure of the a.out
-and COFF support, build a transfer vector (@code{xvec}) for your new format,
-and start populating it with routines. Add it to the list in
+If you need to add a new object file format, you must first add it to
+BFD. This is beyond the scope of this document right now. Basically
+you must build a transfer vector (of type @code{bfd_target}), which will
+mean writing all the required routines, and add it to the list in
@file{bfd/targets.c}.
+You must then arrange for the BFD code to provide access to the
+debugging symbols. Generally GDB will have to call swapping routines
+from BFD and a few other BFD internal routines to locate the debugging
+information. As much as possible, GDB should not depend on the BFD
+internal data structures.
+
+For some targets (e.g., COFF), there is a special transfer vector used
+to call swapping routines, since the external data structures on various
+platforms have different sizes and layouts. Specialized routines that
+will only ever be implemented by one object file format may be called
+directly. This interface should be described in a file
+@file{bfd/libxxx.h}, which is included by GDB.
+
If you are adding a new operating system for an existing CPU chip, add a
@file{tm-@var{xos}.h} file that describes the operating system
facilities that are unusual (extra symbol table info; the breakpoint
configuration.)
-@node Languages, Releases, Target, Top
+@node Languages
@chapter Adding a Source Language to GDB
To add other languages to GDB's expression parser, follow the following steps:
@end table
-@node Releases, Partial Symbol Tables, Languages, Top
+@node Releases
@chapter Configuring GDB for Release
From the top level directory (containing @file{gdb}, @file{bfd},
split the document into one overall file and five or so included files.
-@node Partial Symbol Tables, BFD support for GDB, Releases, Top
+@node Partial Symbol Tables
@chapter Partial Symbol Tables
GDB has three types of symbol tables.
little to be gained by trying to free them unless you want to do a lot
more work.
-@node BFD support for GDB, Symbol Reading, Partial Symbol Tables, Top
+@node Types
+@chapter Types
+
+Fundamental Types (e.g., FT_VOID, FT_BOOLEAN).
+
+These are the fundamental types that gdb uses internally. Fundamental
+types from the various debugging formats (stabs, ELF, etc) are mapped into
+one of these. They are basically a union of all fundamental types that
+gdb knows about for all the languages that gdb knows about.
+
+Type Codes (e.g., TYPE_CODE_PTR, TYPE_CODE_ARRAY).
+
+Each time gdb builds an internal type, it marks it with one of these
+types. The type may be a fundamental type, such as TYPE_CODE_INT, or
+a derived type, such as TYPE_CODE_PTR which is a pointer to another
+type. Typically, several FT_* types map to one TYPE_CODE_* type, and
+are distinguished by other members of the type struct, such as whether
+the type is signed or unsigned, and how many bits it uses.
+
+Builtin Types (e.g., builtin_type_void, builtin_type_char).
+
+These are instances of type structs that roughly correspond to fundamental
+types and are created as global types for gdb to use for various ugly
+historical reasons. We eventually want to eliminate these. Note for
+example that builtin_type_int initialized in gdbtypes.c is basically the
+same as a TYPE_CODE_INT type that is initialized in c-lang.c for an
+FT_INTEGER fundamental type. The difference is that the builtin_type is
+not associated with any particular objfile, and only one instance exists,
+while c-lang.c builds as many TYPE_CODE_INT types as needed, with each
+one associated with some particular objfile.
+
+@node BFD support for GDB
@chapter Binary File Descriptor Library Support for GDB
BFD provides support for GDB in several ways:
@c Reading,,Symbol Reading}.
-@node Symbol Reading, Cleanups, BFD support for GDB, Top
+@node Symbol Reading
@chapter Symbol Reading
GDB reads symbols from "symbol files". The usual symbol file is the
@end table
-@node Cleanups, Wrapping, Symbol Reading, Top
+@node Cleanups
@chapter Cleanups
Cleanups are a structured way to deal with things that need to be done
Syntax:
@table @code
+@item struct cleanup *@var{old_chain};
+Declare a variable which will hold a cleanup chain handle.
+
@item @var{old_chain} = make_cleanup (@var{function}, @var{arg});
Make a cleanup which will cause @var{function} to be called with @var{arg}
(a @code{char *}) later. The result, @var{old_chain}, is a handle that can be
since they might never return to your code (they @samp{longjmp} instead).
-@node Wrapping, Frames, Cleanups, Top
+@node Wrapping
@chapter Wrapping Output Lines
Output that goes through @code{printf_filtered} or @code{fputs_filtered} or
warnings are a good example.
-@node Frames, , Wrapping, Top
+@node Frames
@chapter Frames
A frame is a construct that GDB uses to keep track of calling and called
the new frame.
@end table
-@node Host Conditionals, , , Top
+@node Remote Stubs
+@chapter Remote Stubs
+
+GDB's file @file{remote.c} talks a serial protocol to code that runs
+in the target system. GDB provides several sample ``stubs'' that can
+be integrated into target programs or operating systems for this purpose;
+they are named @file{*-stub.c}.
+
+The GDB user's manual describes how to put such a stub into your target
+code. What follows is a discussion of integrating the SPARC stub
+into a complicated operating system (rather than a simple program),
+by Stu Grossman, the author of this stub.
+
+The trap handling code in the stub assumes the following upon entry to
+trap_low:
+
+@enumerate
+@item %l1 and %l2 contain pc and npc respectively at the time of the trap
+@item traps are disabled
+@item you are in the correct trap window
+@end enumerate
+
+As long as your trap handler can guarantee those conditions, then there is no
+reason why you shouldn't be able to `share' traps with the stub. The stub has
+no requirement that it be jumped to directly from the hardware trap vector.
+That is why it calls @code{exceptionHandler()}, which is provided by the external
+environment. For instance, this could setup the hardware traps to actually
+execute code which calls the stub first, and then transfers to its own trap
+handler.
+
+For the most point, there probably won't be much of an issue with `sharing'
+traps, as the traps we use are usually not used by the kernel, and often
+indicate unrecoverable error conditions. Anyway, this is all controlled by a
+table, and is trivial to modify.
+The most important trap for us is for @code{ta 1}. Without that, we
+can't single step or do breakpoints. Everything else is unnecessary
+for the proper operation of the debugger/stub.
+
+From reading the stub, it's probably not obvious how breakpoints work. They
+are simply done by deposit/examine operations from GDB.
+
+@node Longjmp Support
+@chapter Longjmp Support
+
+GDB has support for figuring out that the target is doing a
+@code{longjmp} and for stopping at the target of the jump, if we are
+stepping. This is done with a few specialized internal breakpoints,
+which are visible in the @code{maint info breakpoint} command.
+
+To make this work, you need to define a macro called
+@code{GET_LONGJMP_TARGET}, which will examine the @code{jmp_buf}
+structure and extract the longjmp target address. Since @code{jmp_buf}
+is target specific, you will need to define it in the appropriate
+@file{tm-xxx.h} file. Look in @file{tm-sun4os4.h} and
+@file{sparc-tdep.c} for examples of how to do this.
+
+@node Coding Style
+@chapter Coding Style
+
+GDB is generally written using the GNU coding standards, as described in
+@file{standards.texi}, which you can get from the Free Software
+Foundation. There are some additional considerations for GDB maintainers
+that reflect the unique environment and style of GDB maintenance.
+If you follow these guidelines, GDB will be more consistent and easier
+to maintain.
+
+GDB's policy on the use of prototypes is that prototypes are used
+to @emph{declare} functions but never to @emph{define} them. Simple
+macros are used in the declarations, so that a non-ANSI compiler can
+compile GDB without trouble. The simple macro calls are used like
+this:
+
+@example @code
+extern int
+memory_remove_breakpoint PARAMS ((CORE_ADDR, char *));
+@end example
+
+Note the double parentheses around the parameter types. This allows
+an arbitrary number of parameters to be described, without freaking
+out the C preprocessor. When the function has no parameters, it
+should be described like:
+
+@example @code
+void
+noprocess PARAMS ((void));
+@end example
+
+The @code{PARAMS} macro expands to its argument in ANSI C, or to a simple
+@code{()} in traditional C.
+
+All external functions should have a @code{PARAMS} declaration in a
+header file that callers include. All static functions should have such
+a declaration near the top of their source file.
+
+We don't have a gcc option that will properly check that these rules
+have been followed, but it's GDB policy, and we periodically check it
+using the tools available (plus manual labor), and clean up any remnants.
+
+@node Clean Design
+@chapter Clean Design
+
+In addition to getting the syntax right, there's the little question of
+semantics. Some things are done in certain ways in GDB because long
+experience has shown that the more obvious ways caused various kinds of
+trouble. In particular:
+
+@table @bullet
+@item
+You can't assume the byte order of anything that comes from a
+target (including @var{value}s, object files, and instructions). Such
+things must be byte-swapped using @code{SWAP_TARGET_AND_HOST} in GDB,
+or one of the swap routines defined in @file{bfd.h}, such as @code{bfd_get_32}.
+
+@item
+You can't assume that you know what interface is being used to talk to
+the target system. All references to the target must go through the
+current @code{target_ops} vector.
+
+@item
+You can't assume that the host and target machines are the same machine
+(except in the ``native'' support modules).
+In particular, you can't assume that the target machine's header files
+will be available on the host machine. Target code must bring along its
+own header files -- written from scratch or explicitly donated by their
+owner, to avoid copyright problems.
+
+@item
+Insertion of new @code{#ifdef}'s will be frowned upon. It's much better
+to write the code portably than to conditionalize it for various systems.
+
+@item
+New @code{#ifdef}'s which test for specific compilers or manufacturers
+or operating systems are unacceptable. All @code{#ifdef}'s should test
+for features. The information about which configurations contain which
+features should be segregated into the configuration files. Experience
+has proven far too often that a feature unique to one particular system
+often creeps into other systems; and that a conditional based on
+some predefined macro for your current system will become worthless
+over time, as new versions of your system come out that behave differently
+with regard to this feature.
+
+@item
+Adding code that handles specific architectures, operating systems, target
+interfaces, or hosts, is not acceptable in generic code. If a hook
+is needed at that point, invent a generic hook and define it for your
+configuration, with something like:
+
+@example
+#ifdef WRANGLE_SIGNALS
+ WRANGLE_SIGNALS (signo);
+#endif
+@end example
+
+In your host, target, or native configuration file, as appropriate,
+define @code{WRANGLE_SIGNALS} to do the machine-dependent thing. Take
+a bit of care in defining the hook, so that it can be used by other
+ports in the future, if they need a hook in the same place.
+
+@item
+@emph{Do} write code that doesn't depend on the sizes of C data types,
+the format of the host's floating point numbers, the alignment of anything,
+or the order of evaluation of expressions. In short, follow good
+programming practices for writing portable C code.
+
+@end table
+
+@node Submitting Patches
+@chapter Submitting Patches
+
+Thanks for thinking of offering your changes back to the community of
+GDB users. In general we like to get well designed enhancements.
+Thanks also for checking in advance about the best way to transfer the
+changes.
+
+The two main problems with getting your patches in are,
+
+@table @bullet
+@item
+The GDB maintainers will only install "cleanly designed" patches.
+You may not always agree on what is clean design.
+@pxref{Coding Style}, @pxref{Clean Design}.
+
+@item
+If the maintainers don't have time to put the patch in when it
+arrives, or if there is any question about a patch, it
+goes into a large queue with everyone else's patches and
+bug reports.
+@end table
+
+I don't know how to get past these problems except by continuing to try.
+
+There are two issues here -- technical and legal.
+
+The legal issue is that to incorporate substantial changes requires a
+copyright assignment from you and/or your employer, granting ownership of the changes to
+the Free Software Foundation. You can get the standard document for
+doing this by sending mail to @code{gnu@@prep.ai.mit.edu} and asking for it.
+I recommend that people write in "All programs owned by the
+Free Software Foundation" as "NAME OF PROGRAM", so that changes in
+many programs (not just GDB, but GAS, Emacs, GCC, etc) can be
+contributed with only one piece of legalese pushed through the
+bureacracy and filed with the FSF. I can't start merging changes until
+this paperwork is received by the FSF (their rules, which I follow since
+I maintain it for them).
+
+Technically, the easiest way to receive changes is to receive each
+feature as a small context diff or unidiff, suitable for "patch".
+Each message sent to me should include the changes to C code and
+header files for a single feature, plus ChangeLog entries for each
+directory where files were modified, and diffs for any changes needed
+to the manuals (gdb/doc/gdb.texi or gdb/doc/gdbint.texi). If there
+are a lot of changes for a single feature, they can be split down
+into multiple messages.
+
+In this way, if I read and like the feature, I can add it to the
+sources with a single patch command, do some testing, and check it in.
+If you leave out the ChangeLog, I have to write one. If you leave
+out the doc, I have to puzzle out what needs documenting. Etc.
+
+The reason to send each change in a separate message is that I will
+not install some of the changes. They'll be returned to you with
+questions or comments. If I'm doing my job, my message back to you
+will say what you have to fix in order to make the change acceptable.
+The reason to have separate messages for separate features is so
+that other changes (which I @emph{am} willing to accept) can be installed
+while one or more changes are being reworked. If multiple features
+are sent in a single message, I tend to not put in the effort to sort
+out the acceptable changes from the unacceptable, so none of the
+features get installed until all are acceptable.
+
+If this sounds painful or authoritarian, well, it is. But I get a lot
+of bug reports and a lot of patches, and most of them don't get
+installed because I don't have the time to finish the job that the bug
+reporter or the contributor could have done. Patches that arrive
+complete, working, and well designed, tend to get installed on the day
+they arrive. The others go into a queue and get installed if and when
+I scan back over the queue -- which can literally take months
+sometimes. It's in both our interests to make patch installation easy
+-- you get your changes installed, and I make some forward progress on
+GDB in a normal 12-hour day (instead of them having to wait until I
+have a 14-hour or 16-hour day to spend cleaning up patches before I
+can install them).
+
+@node Host Conditionals
@chapter Host Conditionals
When GDB is configured and compiled, various macros are defined or left
@item KERNELDEBUG
tm-hppa.h
@item MEM_FNS_DECLARED
-defs.h
+Your host config file defines this if it includes
+declarations of @code{memcpy} and @code{memset}. Define this
+to avoid conflicts between the native include
+files and the declarations in @file{defs.h}.
@item NO_SYS_FILE
dbxread.c
-@item USE_PROC_FS
-sparc-tdep.c
@item PYRAMID_CONTROL_FRAME_DEBUGGING
pyr-xdep.c
@item SIGWINCH_HANDLER_BODY
xm-altos.h
@item ASCII_COFF
remote-adapt.c
-@item ATTACH_DETACH
-hppabsd-xdep.c
@item BADMAG
coffread.c
@item BCS
@item BLOCK_ADDRESS_ABSOLUTE
dbxread.c
@item BPT_VECTOR
-tm-68k.h
+tm-m68k.h
@item BREAKPOINT
-tm-68k.h
+tm-m68k.h
@item BREAKPOINT_DEBUG
breakpoint.c
@item BROKEN_LARGE_ALLOCA
-source.c
+Avoid large @code{alloca}'s. For example, on sun's, Large alloca's fail
+because the attempt to increase the stack limit in main() fails because
+shared libraries are allocated just below the initial stack limit. The
+SunOS kernel will not allow the stack to grow into the area occupied by
+the shared libraries.
@item BSTRING
regex.c
@item CALL_DUMMY
hppabsd-tdep.c
@item COFF_FORMAT
symm-tdep.c
-@item COFF_NO_LONG_FILE_NAMES
-coffread.c
@item CORE_NEEDS_RELOCATION
stack.c
@item CPLUS_MARKER
regex.c
@item C_GLBLREG
coffread.c
-@item DAMON
-xcoffexec.c
@item DBXREAD_ONLY
partial-stab.h
@item DBX_PARM_SYMBOL_CLASS
@item EXTERN
buildsym.h
@item EXTRACT_RETURN_VALUE
-tm-68k.h
+tm-m68k.h
@item EXTRACT_STRUCT_VALUE_ADDRESS
values.c
@item EXTRA_FRAME_INFO
frame.h
@item EXTRA_SYMTAB_INFO
symtab.h
-@item FETCH_INFERIOR_REGISTERS
-Define this if the native-dependent code will provide its
-own routines
-@code{fetch_inferior_registers} and @code{store_inferior_registers}.
-If this symbol is @emph{not} defined, the default routines in
-@file{infptrace.c} are used for these functions.
@item FILES_INFO_HOOK
target.c
@item FIXME
@item FRAME_GET_BASEREG_VALUE
frame.h
@item FRAME_NUM_ARGS
-tm-68k.h
+tm-m68k.h
@item FRAME_SPECIFICATION_DYADIC
stack.c
@item FUNCTION_EPILOGUE_SIZE
symtab.c
@item GCC_PRODUCER
dwarfread.c
-@item GDB_TARGET_IS_MACH386
-mach386-xdep.c
-@item GDB_TARGET_IS_SUN3
-a68v-xdep.c
-@item GDB_TARGET_IS_SUN386
-sun386-xdep.c
-@item GET_LONGJMP_TARGET
-i386-tdep.c
@item GET_SAVED_REGISTER
findvar.c
@item GPLUS_PRODUCER
@item HAVE_68881
m68k-tdep.c
@item HAVE_MMAP
-state.c
+In some cases, use the system call @code{mmap} for reading symbol
+tables. For some machines this allows for sharing and quick updates.
@item HAVE_REGISTER_WINDOWS
findvar.c
@item HAVE_SIGSETMASK
infrun.c
@item I80960
remote-vx.c
-@item IBM6000_HOST
-breakpoint.c
-@item IBM6000_TARGET
-buildsym.c
@item IEEE_DEBUG
ieee-float.c
@item IEEE_FLOAT
@item L_LNNO32
coffread.c
@item L_SET
-xm-ultra3.h
+This macro is used as the argument to lseek (or, most commonly, bfd_seek).
+FIXME, it should be replaced by SEEK_SET instead, which is the POSIX equivalent.
@item MACHKERNELDEBUG
hppabsd-tdep.c
@item MAIN
@item MAINTENANCE_CMDS
maint.c
@item MALLOC_INCOMPATIBLE
-defs.h
+Define this if the system's prototype for @code{malloc} differs from the
+@sc{ANSI} definition.
@item MIPSEL
mips-tdep.c
@item MMAP_BASE_ADDRESS
-objfiles.c
+When using HAVE_MMAP, the first mapping should go at this address.
+@item MMAP_INCREMENT
+when using HAVE_MMAP, this is the increment between mappings.
@item MONO
ser-go32.c
@item MOTOROLA
xm-altos.h
-@item NAMES_HAVE_UNDERSCORE
-coffread.c
@item NBPG
altos-xdep.c
@item NEED_POSIX_SETPGID
remote-mm.c
@item NOTICE_SIGNAL_HANDLING_CHANGE
infrun.c
-@item NO_DEFINE_SYMBOL
-xcoffread.c
@item NO_HIF_SUPPORT
remote-mm.c
@item NO_JOB_CONTROL
signals.h
-@item NO_MALLOC_CHECK
-utils.c
@item NO_MMALLOC
-utils.c
-@item NO_MMALLOC
-objfiles.c
-@item NO_MMALLOC
-utils.c
+GDB will use the @code{mmalloc} library for memory allocation for symbol
+reading, unless this symbol is defined. Define it on systems
+on which @code{mmalloc} does not
+work for some reason. One example is the DECstation, where its RPC
+library can't cope with our redefinition of @code{malloc} to call
+@code{mmalloc}. When defining @code{NO_MMALLOC}, you will also have
+to override the setting of @code{MMALLOC_LIB} to empty, in the Makefile.
+Therefore, this define is usually set on the command line by overriding
+@code{MMALLOC_DISABLE} in @file{config/*/*.mh}, rather than by defining
+it in @file{xm-*.h}.
+@item NO_MMALLOC_CHECK
+Define this if you are using @code{mmalloc}, but don't want the overhead
+of checking the heap with @code{mmcheck}.
@item NO_SIGINTERRUPT
remote-adapt.c
@item NO_SINGLE_STEP
infptrace.c
-@item NO_TYPEDEFS
-xcoffread.c
-@item NO_TYPEDEFS
-xcoffread.c
@item NPC_REGNUM
infcmd.c
@item NS32K_SVC_IMMED_OPERANDS
defs.h
@item PS_REGNUM
parse.c
-@item PTRACE_ARG3_TYPE
-inferior.h
-@item PTRACE_FP_BUG
-mach386-xdep.c
-@item PT_ATTACH
-hppabsd-xdep.c
-@item PT_DETACH
-hppabsd-xdep.c
-@item PT_KILL
-infptrace.c
@item PUSH_ARGUMENTS
valops.c
@item PYRAMID_CONTROL_FRAME_DEBUGGING
@item REGISTER_BYTES
remote.c
@item REGISTER_NAMES
-tm-29k.h
-@item REGISTER_U_ADDR
-Defines the offset of the registers in the ``u area''; @pxref{Host}.
+tm-a29k.h
@item REG_STACK_SEGMENT
exec.c
@item REG_STRUCT_HAS_ADDR
@item SEM
coffread.c
@item SET_STACK_LIMIT_HUGE
-infrun.c
+When defined, stack limits will be raised to their maximum. Use this
+if your host supports @code{setrlimit} and you have trouble with
+@code{stringtab} in @file{dbxread.c}.
+
+Also used in @file{fork-child.c} to return stack limits before child
+processes are forked.
@item SHELL_COMMAND_CONCAT
infrun.c
@item SHELL_FILE
@item SIGTRAP_STOP_AFTER_LOAD
infrun.c
@item SKIP_PROLOGUE
-tm-68k.h
+tm-m68k.h
@item SKIP_PROLOGUE_FRAMELESS_P
blockframe.c
@item SKIP_TRAMPOLINE_CODE
core.c
@item SOLIB_CREATE_INFERIOR_HOOK
infrun.c
-@item SOME_NAMES_HAVE_DOT
-minsyms.c
@item SP_REGNUM
parse.c
@item STAB_REG_TO_REGNUM
@item STOP_SIGNAL
main.c
@item STORE_RETURN_VALUE
-tm-68k.h
+tm-m68k.h
@item SUN4_COMPILER_FEATURE
infrun.c
@item SUN_FIXED_LBRAC_BUG
xm-news.h
@item USE_O_NOCTTY
inflow.c
-@item USE_PROC_FS
-inferior.h
@item USE_STRUCT_CONVENTION
values.c
@item USG
xm-m88k.h
@item U_FPSTATE
i386-xdep.c
-@item U_REGS_OFFSET
-This is the offset of the registers in the upage. It need only be defined
-if the generic ptrace register access routines in @file{infptrace.c}
-are being used
-(that is, @code{FETCH_INFERIOR_REGISTERS} is not defined). If the default
-value from @file{infptrace.c} is good enough, leave it undefined.
-
-The default value means that u.u_ar0 @emph{points to} the location of the
-registers. I'm guessing that @code{#define U_REGS_OFFSET 0} means that
-u.u_ar0 @emph{is} the location of the registers.
@item VARIABLES_INSIDE_BLOCK
dbxread.c
@item WRS_ORIG
alloca.c
@item hp800
xm-hppabsd.h
-@item hp9000s800
-dbxread.c
@item hpux
hppabsd-core.c
@item lint
coffread.c
@end table
-@node Target Conditionals, , , Top
+@node Target Conditionals
@chapter Target Conditionals
When GDB is configured and compiled, various macros are defined or left
Eliminate host conditionals from this list as they are identified.}
@table @code
+@item PUSH_DUMMY_FRAME
+Used in @samp{call_function_by_hand} to create an artificial stack frame.
+@item POP_FRAME
+Used in @samp{call_function_by_hand} to remove an artificial stack frame.
@item ALIGN_SIZE
alloca.c
@item BLOCK_ADDRESS_FUNCTION_RELATIVE
main.c
@item KERNELDEBUG
tm-hppa.h
-@item MEM_FNS_DECLARED
-defs.h
@item NO_SYS_FILE
dbxread.c
-@item USE_PROC_FS
-sparc-tdep.c
@item PYRAMID_CONTROL_FRAME_DEBUGGING
pyr-xdep.c
@item SIGWINCH_HANDLER_BODY
xm-altos.h
@item ASCII_COFF
remote-adapt.c
-@item ATTACH_DETACH
-hppabsd-xdep.c
@item BADMAG
coffread.c
@item BCS
@item BLOCK_ADDRESS_ABSOLUTE
dbxread.c
@item BPT_VECTOR
-tm-68k.h
+tm-m68k.h
@item BREAKPOINT
-tm-68k.h
+tm-m68k.h
@item BREAKPOINT_DEBUG
breakpoint.c
-@item BROKEN_LARGE_ALLOCA
-source.c
@item BSTRING
regex.c
@item CALL_DUMMY
hppabsd-tdep.c
@item COFF_FORMAT
symm-tdep.c
-@item COFF_NO_LONG_FILE_NAMES
-coffread.c
@item CORE_NEEDS_RELOCATION
stack.c
@item CPLUS_MARKER
regex.c
@item C_GLBLREG
coffread.c
-@item DAMON
-xcoffexec.c
@item DBXREAD_ONLY
partial-stab.h
@item DBX_PARM_SYMBOL_CLASS
@item EXTERN
buildsym.h
@item EXTRACT_RETURN_VALUE
-tm-68k.h
+tm-m68k.h
@item EXTRACT_STRUCT_VALUE_ADDRESS
values.c
@item EXTRA_FRAME_INFO
mach386-xdep.c
@item FP_REGNUM
parse.c
+@item FPU
+Unused? 6-oct-92 rich@@cygnus.com. FIXME.
@item FRAMELESS_FUNCTION_INVOCATION
blockframe.c
@item FRAME_ARGS_ADDRESS_CORRECT
@item FRAME_GET_BASEREG_VALUE
frame.h
@item FRAME_NUM_ARGS
-tm-68k.h
+tm-m68k.h
@item FRAME_SPECIFICATION_DYADIC
stack.c
@item FUNCTION_EPILOGUE_SIZE
symtab.c
@item GCC_PRODUCER
dwarfread.c
+@item GDB_TARGET_IS_HPPA
+This determines whether horrible kludge code in dbxread.c and partial-stab.h
+is used to mangle multiple-symbol-table files from HPPA's. This should all
+be ripped out, and a scheme like elfread.c used.
@item GDB_TARGET_IS_MACH386
mach386-xdep.c
@item GDB_TARGET_IS_SUN3
@item GDB_TARGET_IS_SUN386
sun386-xdep.c
@item GET_LONGJMP_TARGET
-i386-tdep.c
+For most machines, this is a target-dependent parameter. On the DECstation
+and the Iris, this is a native-dependent parameter, since <setjmp.h> is
+needed to define it.
+
+This macro determines the target PC address that longjmp() will jump
+to, assuming that we have just stopped at a longjmp breakpoint. It
+takes a CORE_ADDR * as argument, and stores the target PC value through
+this pointer. It examines the current state of the machine as needed.
@item GET_SAVED_REGISTER
findvar.c
@item GPLUS_PRODUCER
partial-stab.h
@item HAVE_68881
m68k-tdep.c
-@item HAVE_MMAP
-state.c
@item HAVE_REGISTER_WINDOWS
findvar.c
@item HAVE_SIGSETMASK
infrun.c
@item I80960
remote-vx.c
-@item IBM6000_HOST
-breakpoint.c
@item IBM6000_TARGET
-buildsym.c
+Shows that we are configured for an IBM RS/6000 target. This conditional
+should be eliminated (FIXME) and replaced by feature-specific macros.
+It was introduced in haste and we are repenting at leisure.
@item IEEE_DEBUG
ieee-float.c
@item IEEE_FLOAT
defs.h
@item LONG_MAX
defs.h
-@item LSEEK_NOT_LINEAR
-source.c
@item L_LNNO32
coffread.c
-@item L_SET
-xm-ultra3.h
@item MACHKERNELDEBUG
hppabsd-tdep.c
@item MAIN
maint.c
@item MIPSEL
mips-tdep.c
-@item MMAP_BASE_ADDRESS
-objfiles.c
@item MOTOROLA
xm-altos.h
-@item NAMES_HAVE_UNDERSCORE
-coffread.c
@item NBPG
altos-xdep.c
@item NEED_POSIX_SETPGID
remote-mm.c
@item NOTICE_SIGNAL_HANDLING_CHANGE
infrun.c
-@item NO_DEFINE_SYMBOL
-xcoffread.c
@item NO_HIF_SUPPORT
remote-mm.c
-@item NO_JOB_CONTROL
-signals.h
-@item NO_MALLOC_CHECK
-utils.c
-@item NO_MMALLOC
-utils.c
-@item NO_MMALLOC
-objfiles.c
-@item NO_MMALLOC
-utils.c
@item NO_SIGINTERRUPT
remote-adapt.c
@item NO_SINGLE_STEP
infptrace.c
@item NO_TYPEDEFS
-xcoffread.c
-@item NO_TYPEDEFS
-xcoffread.c
+xcoffread.c--This causes types not to be read, to save memory and speed
+things up.
@item NPC_REGNUM
infcmd.c
@item NS32K_SVC_IMMED_OPERANDS
defs.h
@item PS_REGNUM
parse.c
-@item PTRACE_ARG3_TYPE
-inferior.h
-@item PTRACE_FP_BUG
-mach386-xdep.c
@item PUSH_ARGUMENTS
valops.c
@item REGISTER_BYTES
remote.c
@item REGISTER_NAMES
-tm-29k.h
+tm-a29k.h
@item REG_STACK_SEGMENT
exec.c
@item REG_STRUCT_HAS_ADDR
state.c
@item SEM
coffread.c
-@item SET_STACK_LIMIT_HUGE
-infrun.c
@item SHELL_COMMAND_CONCAT
infrun.c
@item SHELL_FILE
@item SIGTRAP_STOP_AFTER_LOAD
infrun.c
@item SKIP_PROLOGUE
-tm-68k.h
+tm-m68k.h
@item SKIP_PROLOGUE_FRAMELESS_P
blockframe.c
@item SKIP_TRAMPOLINE_CODE
core.c
@item SOLIB_CREATE_INFERIOR_HOOK
infrun.c
-@item SOME_NAMES_HAVE_DOT
-minsyms.c
@item SP_REGNUM
parse.c
@item STAB_REG_TO_REGNUM
@item STOP_SIGNAL
main.c
@item STORE_RETURN_VALUE
-tm-68k.h
+tm-m68k.h
@item SUN4_COMPILER_FEATURE
infrun.c
@item SUN_FIXED_LBRAC_BUG
alloca.c
@item hp800
xm-hppabsd.h
-@item hp9000s800
-dbxread.c
@item hpux
hppabsd-core.c
@item longest_to_int
coffread.c
@end table
+@node Native Conditionals
+@chapter Native Conditionals
+
+When GDB is configured and compiled, various macros are defined or left
+undefined, to control compilation when the host and target systems
+are the same. These macros should be defined (or left undefined)
+in @file{nm-@var{system}.h}.
+
+@table @code
+@item ATTACH_DETACH
+If defined, then gdb will include support for the @code{attach} and
+@code{detach} commands.
+@item FETCH_INFERIOR_REGISTERS
+Define this if the native-dependent code will provide its
+own routines
+@code{fetch_inferior_registers} and @code{store_inferior_registers} in
+@file{@var{HOST}-nat.c}.
+If this symbol is @emph{not} defined, and @file{infptrace.c}
+is included in this configuration, the default routines in
+@file{infptrace.c} are used for these functions.
+@item GET_LONGJMP_TARGET
+For most machines, this is a target-dependent parameter. On the DECstation
+and the Iris, this is a native-dependent parameter, since <setjmp.h> is
+needed to define it.
+
+This macro determines the target PC address that longjmp() will jump
+to, assuming that we have just stopped at a longjmp breakpoint. It
+takes a CORE_ADDR * as argument, and stores the target PC value through
+this pointer. It examines the current state of the machine as needed.
+@item PROC_NAME_FMT
+Defines the format for the name of a @file{/proc} device. Should be
+defined in @file{nm.h} @emph{only} in order to override the default
+definition in @file{procfs.c}.
+@item PTRACE_FP_BUG
+mach386-xdep.c
+@item PTRACE_ARG3_TYPE
+The type of the third argument to the @code{ptrace} system call, if it exists
+and is different from @code{int}.
+@item REGISTER_U_ADDR
+Defines the offset of the registers in the ``u area''; @pxref{Host}.
+@item USE_PROC_FS
+This determines whether small routines in @file{*-tdep.c}, which
+translate register values
+between GDB's internal representation and the /proc representation,
+are compiled.
+@item U_REGS_OFFSET
+This is the offset of the registers in the upage. It need only be
+defined if the generic ptrace register access routines in
+@file{infptrace.c} are being used (that is,
+@file{infptrace.c} is configured in, and
+@code{FETCH_INFERIOR_REGISTERS} is not defined). If the default value
+from @file{infptrace.c} is good enough, leave it undefined.
+
+The default value means that u.u_ar0 @emph{points to} the location of the
+registers. I'm guessing that @code{#define U_REGS_OFFSET 0} means that
+u.u_ar0 @emph{is} the location of the registers.
+@end table
+
+@node Obsolete Conditionals
+@chapter Obsolete Conditionals
+
+Fragments of old code in GDB sometimes reference or set the following
+configuration macros. They should not be used by new code, and
+old uses should be removed as those parts of the debugger are
+otherwise touched.
+
+@table @code
+@item STACK_END_ADDR
+This macro used to define where the end of the stack appeared, for use
+in interpreting core file formats that don't record this address in the
+core file itself. This information is now configured in BFD, and GDB
+gets the info portably from there. The values in GDB's configuration
+files should be moved into BFD configuration files (if needed there),
+and deleted from all of GDB's config files.
+
+Any @file{@var{foo}-xdep.c} file that references STACK_END_ADDR
+is so old that it has never been converted to use BFD. Now that's old!
+@end table
+
+@node XCOFF
+@chapter The XCOFF Object File Format
+
+The IBM RS/6000 running AIX uses an object file format called xcoff.
+The COFF sections, symbols, and line numbers are used, but debugging
+symbols are dbx-style stabs whose strings are located in the
+@samp{.debug} section (rather than the string table). Files are
+indicated with a @samp{C_FILE} symbol (.file) which is analogous to
+@samp{N_SO}; include files are delimited with @samp{C_BINCL} (.bi) and
+@samp{C_EINCL} (.ei) which correspond to @samp{N_SOL} rather than Sun's
+@samp{N_BINCL} (that is, they don't nest and there is no equivalent to
+N_EXCL). The values of the @samp{C_BINCL} and @samp{C_EINCL} symbols
+are offsets into the executable file which point to the beginning and
+the end of the portion of the linetable which correspond to this include
+file (warning: C_EINCL is inclusive not exclusive like most end of
+something pointers). Other differences from standard stabs include the
+use of negative type numbers for builtin types.
+
+The shared library scheme has a nice clean interface for figuring out
+what shared libraries are in use, but the catch is that everything which
+refers to addresses (symbol tables and breakpoints at least) needs to be
+relocated for both shared libraries and the main executable. At least
+using the standard mechanism this can only be done once the program has
+been run (or the core file has been read).
+
@contents
@bye
projects / binutils.git / blobdiff