Re: RFA: Patch for corefile support

[Daniel Jacobowitz <drow@mvista.com>]

On Mon, Feb 03, 2003 at 05:58:19PM -0500, J. Johnston wrote:
> 
> 
> Daniel Jacobowitz wrote:
> >On Sat, Feb 01, 2003 at 02:22:02PM +0100, Mark Kettenis wrote:
> >
> >>"J. Johnston" <jjohnstn@redhat.com> writes:
> >>
> >>
> >>>The attached patch fixes a problem in gdb when a corefile is read in
> >>>after a multithreaded application has been debugged.  What happens is 
> >>>that
> >>>the thread-db and lin-lwp layers are still around and run into internal
> >>>errors.
> >>>
> >>>The solution is simply to unpush the thread-db ops in its mourn_inferior
> >>>routine.  If a corefile gets loaded, there is no thread-db to interfere.
> >>>If another multi-threaded app gets loaded, the thread_db_new_objfile is
> >>>designed to bring back the thread-db layer as needed.
> >>>
> >>>This fix solves another failure in the killed.exp testsuite as well.
> >>>
> >>>Ok to commit?
> >>
> >>Sorry, no.  AFAICT this will break debugging programs that are
> >>statically linked against libpthread.  As a minimum, this code should
> >>check keep_thread_db before unpushing the target, but even then, I'm
> >>not sure whether this is really OK.
> >
> >
> >Programs statically linked against libpthread are already broken.  I
> >have a patch to fix it, but it's so gross that I haven't posted it; I
> >still can't think of a good way to do it.
> >
> >Given the way GDB treats targets, we seem to be waffling; someone fixes
> >core file support and breaks static binaries, or vice versa.
> >
> 
> So, is there a scenario where my patch would be wrong?  I am seeing what you
> discussed.  Statically linked multi-threaded programs don't work with gdb
> because we never set up the thread_db_ops layer to begin with
> (thread_db_new_objfile never gets called with a non-null objfile with
> the target_has_execution flag on).

I don't know.  The whole way in which thread_db is initialized right
now is a little bit confusing.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer