Re: [PATCH 2/2] perf top: Properly notify the user that vmlinux ismissing

From: Ingo Molnar
Date: Tue Mar 16 2010 - 05:55:44 EST



* David Miller <davem@xxxxxxxxxxxxx> wrote:

> From: Ingo Molnar <mingo@xxxxxxx>
> Date: Tue, 16 Mar 2010 10:46:11 +0100
>
> > i'd really like that to happen - i.e. if we had the kernel (and modules) image
> > exposed as a (almost-)standard ELF object via /sys or so.
> >
> > We already have some aspects of that, via /sys/kernel/notes, but it should be
> > done for real. That would also make build-id support less of a hack.
> >
> > ( I'd not include CFI debuginfo in there though - that would be way too large.
> > More compressed debuginfo could be included perhaps. )
>
> That's interesting and useful, but wouldn't help my case as the images I'm
> usually booting are completely stripped.

/me too

> That's why I end up with "[kernel.kallsyms]" for kernel profiling :-)

The kernel image itself is still present in RAM, obviously. So are the symbols
(packed for kallsyms).

So exposing a virtual ELF image via /sys (or /proc/kernel.so) wouldnt take up
much more RAM and would be rather useful, right?

Ingo
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