Re: [patch][rfc] Allow GDB to search for the right libthread_db.so.1

[Paul Pluzhnikov <ppluzhnikov@google.com>]

On Thu, Apr 30, 2009 at 11:55 AM, Joel Brobecker <brobecker@adacore.com> wrote:

>> 1. If libthread_db_search_path is set, use it *before* trying to load
>>    libthread_db from the same directory where libpthread was loaded in the
>>    inferior.
>
> From my naive perspective (never really had a need for this feature),
> it seems better to check the path before checking the path that was
> used by the inferior.  Otherwise, if the local host has a library
> at the same location but that's different from the library used
> by the inferior, we wouldn't be able to force the debugger to use
> a different library, would we?

Assume inferior is using remote:/a/b/c/libpthread.so.0.

If host has local:/a/b/c/libthread_db.so.0 which is incompatible with
remote:/a/b/c/libpthread.so.0, then
try_thread_db_load("/a/b/c/libthread_db.so.0")
will fail, and GDB will proceed to try other paths in
libthread_db_search_path.

But I see your point: if local:/a/b/c/libthread_db.so.0 "agrees"
to work with the inferior (td_ta_new returns TD_OK), yet is the wrong one
to use for some reason, there is no way for the user to force GDB to use
an alternate libthread_db.

I'll invert the order of search, get rid of symbol lookup, and send an
updated patch shortly.

Thanks,
-- 
Paul Pluzhnikov