libpython2.4.so: Cannot load symbols for shared library with separate debuginfo

libpython2.4.so: Cannot load symbols for shared library with separate debuginfo

[Alejandro Homs]

Hi,

I am trying to debug a Python C++ extension module. I have installed:

python-2.4-14:
  /usr/bin/python2.4              -> stripped
  /usr/lib/libpython.2.4.so.1.0   -> not stripped
python-debug-info-2.4.14:
  /usr/lib/debug/usr/bin/python2.4.debug
  /usr/lib/debug/usr/lib/libpython2.4.so.1.0.debug

I installed the latest gdb-6.6. When I load the core file, gdb reads the
symbols from python2.4.debug, but it does not read the
libpython2.4.so.1.0.debug with the debug information for the shared library.
I guess this is because it finds some symbols already on
libpython2.4.so.1.0, and does not attempt to search the separate debuginfo
file.

I tried with the symbol-file command, but it does not work. 

What can I do to debug libpython2.4.so?

Thanks a lot in advance

Alejandro

Re: libpython2.4.so: Cannot load symbols for shared library with separate debuginfo

[Daniel Jacobowitz]

On Thu, Jun 07, 2007 at 03:28:38PM +0200, Alejandro Homs wrote:
> Hi,
> 
> I am trying to debug a Python C++ extension module. I have installed:
> 
> python-2.4-14:
>   /usr/bin/python2.4              -> stripped
>   /usr/lib/libpython.2.4.so.1.0   -> not stripped
> python-debug-info-2.4.14:
>   /usr/lib/debug/usr/bin/python2.4.debug
>   /usr/lib/debug/usr/lib/libpython2.4.so.1.0.debug
> 
> I installed the latest gdb-6.6. When I load the core file, gdb reads the
> symbols from python2.4.debug, but it does not read the
> libpython2.4.so.1.0.debug with the debug information for the shared library.
> I guess this is because it finds some symbols already on
> libpython2.4.so.1.0, and does not attempt to search the separate debuginfo
> file.

It should always try to load the separate debug file.  Is
debug-file-directory set to /usr/lib/debug, and is there a
.gnu_debuglink section in libpython.2.4.so.1.0?  You may have
to debug GDB to find out what it thinks it's doing.

-- 
Daniel Jacobowitz
CodeSourcery

RE: libpython2.4.so: Cannot load symbols for shared library with separate debuginfo

[Alejandro Homs]

Thanks a lot for your fast response!

> It should always try to load the separate debug file.  Is
> debug-file-directory set to /usr/lib/debug, and is there a
> .gnu_debuglink section in libpython.2.4.so.1.0?  You may have
> to debug GDB to find out what it thinks it's doing.

You are right, the debug-file-directory is pointing to /usr/lib/debug, but
there is no .gnu_debuglink section in libpython.2.4.so.1.0.
I am obliged to generate the .gnu_debuglink section? 

I did it already with objcopy and it works!! But I had to modify
/usr/lib/libpython2.4.so.1.0 ...

Thanks again for your help!

Alejandro

Re: libpython2.4.so: Cannot load symbols for shared library with separate debuginfo

['Daniel Jacobowitz']

On Thu, Jun 07, 2007 at 05:31:11PM +0200, Alejandro Homs wrote:
> Thanks a lot for your fast response!
> 
> > It should always try to load the separate debug file.  Is
> > debug-file-directory set to /usr/lib/debug, and is there a
> > .gnu_debuglink section in libpython.2.4.so.1.0?  You may have
> > to debug GDB to find out what it thinks it's doing.
> 
> You are right, the debug-file-directory is pointing to /usr/lib/debug, but
> there is no .gnu_debuglink section in libpython.2.4.so.1.0.
> I am obliged to generate the .gnu_debuglink section? 

Yes; to use a separate debug file you need both --only-keep-debug and
--add-gnu-debuglink.

-- 
Daniel Jacobowitz
CodeSourcery

Re: libpython2.4.so: Cannot load symbols for shared library with separate debuginfo

[Andreas Schwab]

"Alejandro Homs" <ahoms@cells.es> writes:

> Thanks a lot for your fast response!
>
>> It should always try to load the separate debug file.  Is
>> debug-file-directory set to /usr/lib/debug, and is there a
>> .gnu_debuglink section in libpython.2.4.so.1.0?  You may have
>> to debug GDB to find out what it thinks it's doing.
>
> You are right, the debug-file-directory is pointing to /usr/lib/debug, but
> there is no .gnu_debuglink section in libpython.2.4.so.1.0.
> I am obliged to generate the .gnu_debuglink section? 

If there is no debuglink section then the debug info file most likely
does not belong to this library.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
PGP key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

RE: libpython2.4.so: Cannot load symbols for shared library with separate debuginfo

[Alejandro Homs]

> >> It should always try to load the separate debug file.  Is
> >> debug-file-directory set to /usr/lib/debug, and is there a
> >> .gnu_debuglink section in libpython.2.4.so.1.0?  You may have
> >> to debug GDB to find out what it thinks it's doing.
> >
> > You are right, the debug-file-directory is pointing to /usr/lib/debug,
> but
> > there is no .gnu_debuglink section in libpython.2.4.so.1.0.
> > I am obliged to generate the .gnu_debuglink section?
> 
> If there is no debuglink section then the debug info file most likely
> does not belong to this library.

That's a very strange thing. All the other libraries in the same package
have the .gnu_debuglink section. And the debuginfo package was built with
the same timestamp ... I don't know if this was removed intentionally by
SuSE ... I do not have the SRPM of that package, so I will check with recent
package versions.

Anyway, as I said in my previous mail, objcopy did the job, and it works!
Thanks

Alejandro