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[binutils.git] / gdb / WHATS.NEW

		What has changed since GDB-3.5?


 *  GDB and Modula-2

GDB now has preliminary support for the GNU Modula-2 compiler,
currently under development at the State University of New York at
Buffalo.  Development of both GDB and the GNU Modula-2 compiler will
continue through the fall of 1991 and into 1992.

Other Modula-2 compilers are currently not supported, and attempting to
debug programs compiled with them will likely result in an error as the
symbol table of the executable is read in.

 *  New Facilities

Wide output is wrapped at good places to make the output more readable.

Gdb now supports cross-debugging from a host machine of one type to a
target machine of another type.  Communication with the target system
is over serial lines.  The ``target'' command handles connecting to the
remote system; the ``load'' command will download a program into the
remote system.  Serial stubs for the m68k and i386 are provided.  Gdb
also supports debugging of realtime processes running under VxWorks,
using SunRPC Remote Procedure Calls over TCP/IP to talk to a debugger
stub on the target system.

New CPUs supported include the AMD 29000 and Intel 960.

GDB now reads object files and symbol tables via a ``binary file'' 
library, which allows a single copy of GDB to debug programs of multiple
object file types such as a.out and coff.

There is now a GDB reference card in "doc/refcard.tex".  (Make targets
refcard.dvi and refcard.ps are available to format it).


 *  Control-Variable user interface simplified

All variables that control the operation of the debugger can be set
by the ``set'' command, and displayed by the ``show'' command.

For example, ``set prompt new-gdb=>'' will change your prompt to new-gdb=>.
``Show prompt'' produces the response:
Gdb's prompt is new-gdb=>.

What follows are the NEW set commands.  The command ``help set'' will
print a complete list of old and new set commands.  ``help set FOO''
will give a longer description of the variable FOO.  ``show'' will show
all of the variable descriptions and their current settings.

confirm on/off:  Enables warning questions for operations that are
		 hard to recover from, e.g. rerunning the program while
		 it is already running.  Default is ON.

editing on/off:  Enables EMACS style command line editing 
                 of input.  Previous lines can be recalled with 
		 control-P, the current line can be edited with control-B,
		 you can search for commands with control-R, etc.
		 Default is ON.

history filename NAME:  NAME is where the gdb command history 
			will be stored.  The default is .gdb_history,
			or the value of the environment variable
			GDBHISTFILE.

history size N:  The size, in commands, of the command history.  The 
		 default is 256, or the value of the environment variable
		 HISTSIZE.

history save on/off: If this value is set to ON, the history file will
		      be saved after exiting gdb.  If set to OFF, the 
		      file will not be saved.  The default is OFF.

history expansion on/off: If this value is set to ON, then csh-like 
			  history expansion will be performed  on 
			  command line input.  The default is OFF.

radix N:  Sets the default radix for input and output.  It can be set
	  to 8, 10, or 16.  Note that the argument to "radix" is interpreted
	  in the current radix, so "set radix 10" is always a no-op.

height N: This integer value is the number of lines on a page. Default
          is 24, the current `stty rows'' setting, or the ``li#''
	  setting from the termcap entry matching the environment
	  variable TERM.

width N:  This integer value is the number of characters on a line.
	  Default is 80, the current `stty cols'' setting, or the ``co#''
	  setting from the termcap entry matching the environment
	  variable TERM.

Note: ``set screensize'' is obsolete. Use ``set height'' and
``set width'' instead.

print address on/off:  Print memory addresses in various command displays,
		      such as stack traces and structure values.  Gdb looks
		      more ``symbolic'' if you turn this off; it looks more
		      ``machine level'' with it on.  Default is ON.

print array on/off:  Prettyprint arrays.  New convenient format!  Default 
                    is OFF.

print demangle on/off:   Print C++ symbols in "source" form if on,
			"raw" form if off.

print asm-demangle on/off:  Same, for assembler level printouts
			like instructions.

print vtbl on/off:  Prettyprint C++ virtual function tables.  Default is OFF.

write on/off:  GDB can now write to executable and core files (e.g. patch
		a variable's value) if you turn this switch on, specify
		the file ("exec foo" or "core foo"), then modify it, e.g.
		by assigning a new value to a variable.

 *  Support for Epoch Environment.

The epoch environment is a version of Emacs v18 with windowing.  One
new command, ``inspect'', is identical to ``print'', except that if you
are running in the epoch environment, the value is printed in its own
window.


 *  Support for Shared Libraries

GDB can now debug programs and core files that use SunOS shared libraries.
Symbols from a shared library cannot be referenced
before the shared library has been linked with the program (this
happens after you type ``run'' and before the function main() is entered).
At any time after this linking (including when examining core files
from dynamically linked programs), gdb reads the symbols from each
shared library when you type the ``sharedlibrary'' command.
It can be abbreviated ``share''.

sharedlibrary REGEXP:  Load shared object library symbols for files 
                       matching a unix regular expression.  No argument
		       indicates to load symbols for all shared libraries.

info sharedlibrary:  Status of loaded shared libraries.


 *  Watchpoints

A watchpoint stops execution of a program whenever the value of an
expression changes.  Checking for this slows down execution
tremendously whenever you are in the scope of the expression, but is
quite useful for catching tough ``bit-spreader'' or pointer misuse
problems.  Some machines such as the 386 have hardware for doing this
more quickly, and future versions of gdb will use this hardware.

watch EXP:  Set a watchpoint (breakpoint) for an expression.

info watchpoints:  Information about your watchpoints.

delete N:   Deletes watchpoint number N (same as breakpoints).
disable N:  Temporarily turns off watchpoint number N (same as breakpoints).
enable N:   Re-enables watchpoint number N (same as breakpoints).


 *  C++ multiple inheritance

When used with a GCC version 2 compiler, GDB supports multiple inheritance
for C++ programs.

 *  C++ exception handling

Gdb now supports limited C++ exception handling.  Besides the existing
ability to breakpoint on an exception handler, gdb can breakpoint on
the raising of an exception (before the stack is peeled back to the
handler's context).

catch FOO:  If there is a FOO exception handler in the dynamic scope,
	    set a breakpoint to catch exceptions which may be raised there.
	    Multiple exceptions (``catch foo bar baz'') may be caught.

info catch:  Lists all exceptions which may be caught in the
             current stack frame.


 *  Minor command changes

The command ``call func (arg, arg, ...)'' now acts like the print
command, except it does not print or save a value if the function's result
is void.  This is similar to dbx usage.

The ``up'' and ``down'' commands now always print the frame they end up
at; ``up-silently'' and `down-silently'' can be used in scripts to change
frames without printing.

 *  New directory command

'dir' now adds directories to the FRONT of the source search path.
The path starts off empty.  Source files that contain debug information
about the directory in which they were compiled can be found even
with an empty path; Sun CC and GCC include this information.  If GDB can't
find your source file in the current directory, type "dir .".

 * Configuring GDB for compilation

For normal use, type ``./configure host''.  See README or gdb.texinfo
for more details.

GDB now handles cross debugging.  If you are remotely debugging between 
two different machines, type ``./configure host -target=targ''.
Host is the machine where gdb will run; targ is the machine
where the program that you are debugging will run.