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Re: Location of modules with debug info


Roberto Jung Drebes <drebes@gmail.com> writes:

> [...]
>> Where did you get that one?  It doesn't appear to be in the standard
>> 9.04 repositories.
>> (https://bugs.launchpad.net/ubuntu/+source/linux/+bug/289087)
>
> I had to recompile my own packages changing skipdbg=true to
> skipdbg=false.

OK, I'm doing a similar run to reproduce the problem here. 
(Next time you rebuild, consider applying the utrace patches too:
http://people.redhat.com/roland/utrace/old/2.6.28/.)


> [...]
> [root@rerun ~]# find /lib/modules/2.6.28-15-generic/ -name snd.ko |
> xargs ls -l
> -rw-r--r-- 1 root root 114496 2009-09-28 15:08 /lib/modules/2.6.28-15-
> generic/kernel/sound/core/snd.ko
> [root@rerun ~]# find /usr/lib/debug/lib/modules/2.6.28-15-generic/ -
> name snd.ko | xargs ls -l
> -rw-r--r-- 1 root root 1604291 2009-09-28 15:12 /usr/lib/debug/lib/
> modules/2.6.28-15-generic/kernel/sound/core/snd.ko

> So I guess stap is just trying to use the first one, without even
> looking for the second. Is there any way I can specify the location?

Hm, it seems as though the /usr/lib/debug copy is the original
unstripped one, and snd.ko is simply stripped.  In Fedora land, we're
more used to separated debuginfo (so /usr/lib/debug/lib/modules/.../
ends up containing snd.ko.debug -- with only the .debug_* sections
included).

The stripped file probably doesn't have a ".gnu_debuglink" section
(confirm with readelf -S), so elfutils doesn't know that it should
bother looking in /usr/lib/debug for an alternative version.
(Roland?)

Regardless, if the /usr/lib/debug/lib copy of the module.ko is indeed
complete (it has all the .text etc. sections), you could just
overwrite the stripped copies in /lib/modules, and all should work.

- FChE


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