Re: RFA: Patch for corefile support

["J. Johnston" <jjohnstn@redhat.com>]

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).

-- Jeff J.