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SubjectRe: [tip:perf/urgent] perf symbols: Handle /proc/sys/kernel/kptr_restrict
Em Thu, May 26, 2011 at 09:39:46PM +0200, Ingo Molnar escreveu:
> Secondly, even though i have the proper 'vmlinux' in cwd, i get half
> a page long warnings on perf record warning me about the vmlinux:
>
> WARNING: Kernel address maps (/proc/{kallsyms,modules}) are restricted, check /proc/sys/kernel/kptr_restrict.
>
> Samples in kernel functions may not be resolved if a suitable
> vmlinux file is not found in the buildid cache or in the vmlinux
> path.
>
> ...
>
> But a vmlinux file *is* in the cwd.

Well, there was no assumption that 'perf report' would run on the same
directory as 'perf record', the user may have moved to a different
directory or transferred the perf.data file to a different machine.

Also it would have to check that the vmlinux on the path is suitable
(that build-id matches), currently it does that just at 'perf report'
time, that is when it will need to use it. At record time we just
collect the build-ids.

With that in mind, how do you think it should be phrased?

- Arnaldo


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