Re: RFC: support debug info in separate files

[Elena Zannoni <ezannoni at redhat dot com>]

Jim Blandy writes:
 > 
 > This patch, written by Alexander Larsson, allows GDB to use debug info
 > that has been extracted into a separate executable file, using the
 > "strip -f" command as provided in Ulrich Drepper's elfutils.  This
 > allows a distribution to provide debug info in separate packages from
 > the executables it describes.
 > 

Actually thinking about this, where can one get a copy of elfutils?
Could the same functionality be added to binutils?

 > If you've got all the previous patches I've posted (and if I haven't
 > botched anything), this should cause no test suite regressions, and
 > the results of running the test suite both with and without separated
 > debug info are identical.  Starting with current GDB sources, the
 > other patches you need are:
 > 
 > RFA: testsuite: pass optimization flag in the proper way
 > RFA: testsuite: attach.exp: don't move executables to /tmp
 > Re: RFC: allow syms_from_objfile to take a section offset table directly
 > RFC: Allow symbol_file_add to take section_offsets table
 > 
 > To run the GDB test suite against executables with separated debug info, 
 > see: http://sources.redhat.com/ml/gdb/2002-11/msg00202.html
 > and: http://sources.redhat.com/ml/gdb/2002-11/msg00215.html
 > 
 > (Note: there is a bug in the elfutils strip that causes some stripped
 > executables to crash.  This has been fixed only very recently, so
 > you'll need a bleeding-edge version of elfutils, or else you'll get
 > failures in try_catch.exp due to the inferior crashing.)
 > 
 > If folks don't have concerns about this, I'll commit it on Fri Dec 6.
 > 

Some random comments...

This works only for Elf. Will this interfere when other file formats
are processed? (I haven't tried with a, say, coff file, which is
impossible of course because this is elfutils based).

 > 	* utils.c (calc_crc32): New function.
 > 	* defs.h (calc_crc32): New declaration.

Now we have 4 identical crc32's functions in gdb. Any chance to
delete a few?

For the debug file name suggest looking at HAVE_DOS_BASED_FILE_SYSTEM
in libiberty, and its uses in gdb/source.c.

[...]

 > +  strcat (debugfile, ".debug/");
[...]

 > +  strcat (debugfile, "/");

[...]
 > +  strcat (debugfile, "/");

Should these be DIR_SEPARATOR instead? I guess DJGPP doesn't care though.

In this message,
http://sources.redhat.com/ml/gdb/2002-09/msg00312.html I pointed out a
few things that could be done to improve this patch.  For instance,
instead of adding a completely new objfile that would be only for the
debug info, add the debug info to the existing objfiles.  I haven't
had a chance to see if you changed the patch to do something different
or not.  It also seemed at that stage that we were gaining an extra
copy of the minimal symbols, and this can bloat gdb even more. Was
this changed?

Other comments I pointed out in that message have been addressed by
Alex already.

Elena