Re: perf-probe: issue with latest fedora kernel

[Francis Moreau <francis.moro@gmail.com>]

Arnaldo Carvalho de Melo <acme@ghostprotocols.net> writes:

> Em Thu, Dec 09, 2010 at 04:00:08PM +0100, Francis Moreau escreveu:
>> I'm trying to use perf-probe(1) with the latest F14 kernel
>> (2.6.35.9-64.fc14.x86_64).
>> 
>
>> I also installed kernel-debug-debuginfo-2.6.35.9-64.fc14.x86_64 which
>> contains the running vmlinux image AFAICT.
>> 
>> I added it to the buildid cache:
>> 
>> $ perf buildid-cache -v -a /usr/lib/debug/lib/modules/2.6.35.9-64.fc14.x86_64.debug/vmlinux
>> Adding 4d89e23415d8ab491cfc8ef8aa67764b91cc6787 /usr/lib/debug/lib/modules/2.6.35.9-64.fc14.x86_64.debug/vmlinux: OK
>> 
>> But when running perf-probe(1) like the following:
>> 
>>   $ perf probe schedule cpu
>>   Failed to find path of kernel moduleFailed to open debuginfo file.
>>   Error: Failed to add events. (-2)
>> 
>> it fails.
>> 
>> One strange thing is that when perf read the running kernel build id, it
>> get: 882b1b53eb1d65320e8fa710273aa8493896c4.
>> 
>> Could anybody tell me what I'm doing wrong ?
>
> Can you try using:
>
> $ perf probe -k /usr/lib/debug/lib/modules/2.6.35.9-64.fc14.x86_64.debug/vmlinux <rest of the probe definition>
>
> So that it tries it directly instead of looking into the buildid cache?
>

Well that still fail:

$ perf probe -k /usr/lib/debug/lib/modules/2.6.35.9-64.fc14.x86_64.debug/vmlinux schedule cpu
Failed to find path of kernel moduleFailed to open debuginfo file.
  Error: Failed to add events. (-2)

but that's not really suprising if perf checks that the running kernel
build-id is the same as the one in:
/usr/lib/debug/lib/modules/2.6.35.9-64.fc14.x86_64.debug/vmlinux

It really looks like something is broken in the F14 kernel-debuginfo
package.

thanks
-- 
Francis