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

[Ingo Molnar <mingo@elte.hu>]

* David Miller <davem@davemloft.net> wrote:

> From: Arnaldo Carvalho de Melo <acme@infradead.org>
> Date: Mon, 15 Mar 2010 16:21:26 -0300
> 
> > Em Mon, Mar 15, 2010 at 11:55:26AM -0700, David Miller escreveu:
> >> Arnaldo, if perf top can use the kallsyms to do it's normal task, why
> >> can't it use that for symbol annotations too?  Isn't there enough
> >> information available?
> > 
> > Annotation is done by objdump -dS, that requires an executable file to do 
> > ASM annotation, and one with DWARF info for source code annotation. What 
> > we have with /proc/kallsyms is just the symtab.
> 
> Ok, I really think we should link with libopcodes or similar so we can 
> handle the simple assembler annotation case without requiring the kernel 
> image being available.
> 
> That's what I was trying to achieve when I sent you the report
> :-)

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. )

	Ingo