Re: Patch to enable a fully working gdb for GNU/Hurd

[Svante Signell <svante dot signell at telia dot com>]

On Mon, 2011-07-04 at 21:17 +0200, Svante Signell wrote:
> On Mon, 2011-07-04 at 20:18 +0200, Thomas Schwinge wrote:
> > Hallo!
...
> > I think that update_thread_list (which already is exported) should rather
> > be invoked instead of additionally exporting prune_threads.
> > 
> > But -- I can no longer reproduce the original problem with GDB HEAD.  Can
> > you?
> 
> I haven't compiled gdb for some time now. I can take a look, how to get
> the GDB HEAD? The prune_threads enabled gdb to work properly, and then
> Samuel applied an earlier version of the patch on debian-ports.
> 
> Since then the new Debian gdb maintainer wanted to get this patch
> applied upstream, so I did as was requested. Don't know if it is the
> correct approach or not. I can try to use update_thread_list instead,
> once I have the GDB HEAD files.

I have now built gdb HEAD and found that the patch is no longer needed.
Additionally adding update_thread_list in gnu_nat.c works for gdb-7.2,
will propose the following patch to the Debian bug report #579834 in
case there will be more releases of the 7.2-series until 7.4 is
released.

--- gdb/gnu-nat.c.orig  2011-07-05 15:41:54.000000000 +0200
+++ gdb/gnu-nat.c       2011-07-05 14:27:31.000000000 +0200
@@ -1578,6 +1578,7 @@
          if (--inf->pending_execs == 0)
            /* We're done!  */
            {
+             update_thread_list();
 #if 0                          /* do we need this? */
              prune_threads (1);        /* Get rid of the old shell
threads */
              renumber_threads (0);     /* Give our threads reasonable
names. */

A few observations when building gdb HEAD: GNU gdb (GDB)
7.3.50.20110704-cvs though:

1) I had to uncomment -Werror when compiling gdb/msg_U.c with Debian
4.6.1-1+hurd.1 due to the -Wstrict-aliasing flag set by -Wall, see
below:

msg_U.c: In function 'msg_del_auth':
msg_U.c:505:3: error: dereferencing type-punned pointer will break
strict-aliasing rules [-Werror=strict-aliasing]
msg_U.c:520:3: error: dereferencing type-punned pointer will break
strict-aliasing rules [-Werror=strict-aliasing]
msg_U.c: In function 'msg_get_init_ports':
msg_U.c:957:6: error: dereferencing type-punned pointer will break
strict-aliasing rules [-Werror=strict-aliasing]
msg_U.c: In function 'msg_set_init_ports':
msg_U.c:1050:3: error: dereferencing type-punned pointer will break
strict-aliasing rules [-Werror=strict-aliasing]
msg_U.c: In function 'msg_get_init_ints':
msg_U.c:1481:6: error: dereferencing type-punned pointer will break
strict-aliasing rules [-Werror=strict-aliasing]
msg_U.c: In function 'msg_set_init_ints':
msg_U.c:1573:3: error: dereferencing type-punned pointer will break
strict-aliasing rules [-Werror=strict-aliasing]
msg_U.c: In function 'msg_get_dtable':
msg_U.c:1739:6: error: dereferencing type-punned pointer will break
strict-aliasing rules [-Werror=strict-aliasing]
msg_U.c: In function 'msg_set_dtable':
msg_U.c:1832:3: error: dereferencing type-punned pointer will break
strict-aliasing rules [-Werror=strict-aliasing]
msg_U.c: In function 'msg_get_environment':
msg_U.c:2253:6: error: dereferencing type-punned pointer will break
strict-aliasing rules [-Werror=strict-aliasing]
msg_U.c: In function 'msg_set_environment':
msg_U.c:2345:3: error: dereferencing type-punned pointer will break
strict-aliasing rules [-Werror=strict-aliasing]
msg_U.c: In function 'msg_get_env_variable':
msg_U.c:2511:6: error: dereferencing type-punned pointer will break
strict-aliasing rules [-Werror=strict-aliasing]
msg_U.c: In function 'msg_describe_ports':
msg_U.c:3018:3: error: dereferencing type-punned pointer will break
strict-aliasing rules [-Werror=strict-aliasing]
msg_U.c:3083:6: error: dereferencing type-punned pointer will break
strict-aliasing rules [-Werror=strict-aliasing]
cc1: all warnings being treated as errors

2) When debugging an executable gdb does not find the debugging symbols
for libraries. For example with libc0.3-dbg installed, the symbols are
found with 7.2 but not with 7.3.50 when running the built gdb directly
on an executable having debugging symbols (they are found).