143 lines
6.4 KiB
Plaintext
143 lines
6.4 KiB
Plaintext
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This is GDB, the GNU source-level debugger, presently running under un*x.
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Before compiling GDB, you must tell GDB what kind of machine you are
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running on. To do this, type `config.gdb machine', where machine is
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something like `vax' or `sun2'. For a list of valid machine types,
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type `config.gdb'.
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Normally config.gdb edits the makefile as necessary. If you have to
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edit the makefile on a standard machine listed in config.gdb this
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should be considered a bug and reported as such.
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Once these files are set up, just `make' will do everything,
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producing an executable `gdb' in this directory.
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If you want a new (current to this release) version of the manual, you
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will have to use the gdb.texinfo file provided with this distribution.
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The gdb.texinfo file requires the texinfo-format-buffer command from
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emacs 18.55 or later.
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About languages other than C...
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C++ support has been integrated into gdb. GDB should work with
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FORTRAN programs (if you have problem, please send a bug report), but
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I am not aware of anyone who is working on getting it to use the
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syntax of any language other than C or C++. Pascal programs which use
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sets, subranges, file variables, or nested functions will not
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currently work.
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About -gg format...
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Currently GDB version 3.x does *not* support GCC's -gg format. This
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is because it (in theory) has fast enough startup on dbx debugging
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format object files that -gg format is unnecessary (and hence
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undesirable, since it wastes space and processing power in gcc). I
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would like to hear people's opinions on the amount of time currently
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spent in startup; is it fast enough?
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About remote debugging...
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The two files remote-multi.shar and remote-sa.m68k.shar contain two
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examples of a remote stub to be used with remote.c. The the -multi
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file is a general stub that can probably be running on various
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different flavors of unix to allow debugging over a serial line from
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one machine to another. The remote-sa.m68k.shar is designed to run
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standalone on a 68k type cpu and communicate properley with the
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remote.c stub over a serial line.
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About reporting bugs...
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The correct address for reporting bugs found with gdb is
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"bug-gdb@prep.ai.mit.edu". Please send all bugs to that address.
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About xgdb...
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xgdb.c was provided to us by the user community; it is not an integral
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part of the gdb distribution. The problem of providing visual
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debugging support on top of gdb is peripheral to the GNU project and
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(at least right now) we can't afford to put time into it. So while we
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will be happy to incorporate user fixes to xgdb.c, we do not guarantee
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that it will work and we will not fix bugs reported in it. Someone is
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working on writing a new XGDB, so improving (e.g. by fixing it so that
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it will work, if it doesn't currently) the current one is not worth it.
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For those intersted in auto display of source and the availability of
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an editor while debugging I suggest trying gdb-mode in gnu-emacs.
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Comments on this mode are welcome.
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About the machine-dependent files...
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m-<machine>.h (param.h is a link to this file).
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This file contains macro definitions that express information
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about the machine's registers, stack frame format and instructions.
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<machine>-opcode.h (opcode.h is a link to this file).
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<machine>-pinsn.c (pinsn.c is a link to this file).
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These files contain the information necessary to print instructions
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for your cpu type.
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<machine>-dep.c (dep.c is a link to this file).
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Those routines which provide a low level interface to ptrace and which
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tend to be machine-dependent. (The machine-independent routines are in
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`infrun.c' and `inflow.c')
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About writing code for GDB...
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We appreciate having users contribute code that is of general use, but
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for it to be included in future GDB releases it must be cleanly
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written. We do not want to include changes that will needlessly make future
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maintainance difficult. It is not much harder to do things right, and
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in the long term it is worth it to the GNU project, and probably to
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you individually as well.
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Please code according to the GNU coding standards. If you do not have
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a copy, you can request one by sending mail to gnu@prep.ai.mit.edu.
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Please try to avoid making machine-specific changes to
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machine-independent files (i.e. all files except "param.h" and
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"dep.c". "pinsn.c" and "opcode.h" are processor-specific but not
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operating system-dependent). If this is unavoidable, put a hook in
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the machine-independent file which calls a (possibly)
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machine-dependent macro (for example, the IGNORE_SYMBOL macro can be
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used for any symbols which need to be ignored on a specific machine.
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Calling IGNORE_SYMBOL in dbxread.c is a lot cleaner than a maze of #if
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defined's). The machine-independent code should do whatever "most"
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machines want if the macro is not defined in param.h. Using #if
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defined can sometimes be OK (e.g. SET_STACK_LIMIT_HUGE) but should be
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conditionalized on a specific feature of an operating system (set in
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param.h) rather than something like #if defined(vax) or #if
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defined(SYSV).
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It is better to replace entire routines which may be system-specific,
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rather than put in a whole bunch of hooks which are probably not going
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to be helpful for any purpose other than your changes. For example,
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if you want to modify dbxread.c to deal with DBX debugging symbols
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which are in COFF files rather than BSD a.out files, do something
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along the lines of a macro GET_NEXT_SYMBOL, which could have
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different definitions for COFF and a.out, rather than trying to put
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the necessary changes throughout all the code in dbxread.c that
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currently assumes BSD format.
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Please avoid duplicating code. For example, if something needs to be
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changed in read_inferior_memory, it is very painful because there is a
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copy in every dep.c file. The correct way to do this is to put (in
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this case) the standard ptrace interfaces in a separate file ptrace.c,
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which is used by all systems which have ptrace. ptrace.c would deal
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with variations between systems the same way any system-independent
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file would (hooks, #if defined, etc.).
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About debugging gdb with itself...
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You probably want to do a "make TAGS" after you configure your
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distribution; this will put the machine dependent routines for your
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local machine where they will be accessed first by a M-period .
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Also, make sure that you've compiled gdb with your local cc or taken
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appropriate precautions regarding ansification of include files. See
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the Makefile for more information.
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The "info" command, when executed without a subcommand in a gdb being
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debugged by gdb, will pop you back up to the top level gdb. See
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.gdbinit for more details.
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