[PATCH] nptl: Move stack list variables into _rtld_global

[Florian Weimer]

* Florian Weimer via Gdb-patches:

> * Simon Marchi:
>
>>>> If we have to deal with this, I guess that GDB should now do things in a
>>>> different order: go through the whole library list and load their
>>>> symbols.  And then if one of those libraries were libpthread, try to
>>>> initialize libthread_db.
>>> 
>>> Initialization of libthread_db should be unconditional.  Programs use
>>> TLS data without linking against libpthread.  And glibc 2.34 might not
>>> have a separate libpthread at all.
>>
>> Ok, currently GDB attempts to load libthread_db when noticing the main
>> objfile / program (I guess it is needed if the program is statically
>> linked to libpthread?) or when seeing a library named libpthread*.
>
> Would it be possible to load libthread_db unconditionally after loading
> all shared objects?  Then it is loaded only once.
>
>> About the hypothetical scenario for glibc 2.34: do you mean that the
>> pthread infrastructure will directly be in libc.so?  If so, our current
>> strategy of attempting to load libthread_db only for the main program
>> or a libpthread* library will indeed not work.  And I suppose that will
>> also require trying to load libthread_db on every new shared lib...
>
> I think one attempt loading is enough, after all shared objects are
> available.  In both the attaching and starting case, libpthread will be
> seen by libthread_db if it is there.  I do not think it is necessary to
> try loading libpthread_db again for each dlopen.  Maybe you could
> restrict that to trigger on libpthread, but then dlopen of libpthread
> does not really work today.

I would appreciate if we could make some progress on this issue.
Please let me know if you need glibc test builds or something in that
area.  Thanks.