Re: [Libunwind-devel] Re: Backtrace from signal handler on arm from threads

[Paul Pluzhnikov]

On Thu, Feb 3, 2011 at 7:07 AM, Lassi Tuura <address@hidden> wrote:
> Hi,
>
>>>> Hmm.  Looking at it, it might seem like libpthread is lacking some
>>>> symbols, creating problems.
>>>
>>> Symbols don't affect unwinding, as far as I know.

Symbols do affect GDB though.

In particular, libthread_db looks up "private" libpthread symbols, so
if libpthread is completely stripped, then GDB will not work (in the
way that Henrik described).

>> Yeah, that was another thing I was wondering about...  Can I in some
>> way use strip or other tools to remove debug symbols while keeping
>> unwind info alive?

You should not strip libpthread completely, but stripping debug info
is reasonable and usually done with 'strip -g'.

>>  It currently does not work at all if I don't have
>> my oversized libc and libpthread with full debug info in there.
>
> I am not familiar enough with ARM toolchain to say one way or another.
>
> In terms of what ELF libraries can contain, sure it should be possible.
> The unwind info is in .eh_frame{,_hdr} sections on other platforms. But
> I had understood from other ARM-related mails on this list that some other
> (.debug_frame?) section was used on ARM instead. I don't know if that is
> universal, or specific to one toolchain (IIRC that was uclibc).
>
> Regards,
> Lassi
>
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-- 
Paul Pluzhnikov