From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937322Ab0CPJq0 (ORCPT ); Tue, 16 Mar 2010 05:46:26 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:37864 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932488Ab0CPJqZ (ORCPT ); Tue, 16 Mar 2010 05:46:25 -0400 Date: Tue, 16 Mar 2010 10:46:11 +0100 From: Ingo Molnar To: David Miller Cc: acme@infradead.org, linux-kernel@vger.kernel.org, fweisbec@gmail.com, efault@gmx.de, a.p.zijlstra@chello.nl, paulus@samba.org Subject: Re: [PATCH 2/2] perf top: Properly notify the user that vmlinux is missing Message-ID: <20100316094611.GG7961@elte.hu> References: <1268664418-28328-2-git-send-email-acme@infradead.org> <20100315.115526.52182155.davem@davemloft.net> <20100315192125.GL6965@ghostprotocols.net> <20100315.122605.124976085.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100315.122605.124976085.davem@davemloft.net> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: 0.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=0.0 required=5.9 tests=none autolearn=no SpamAssassin version=3.2.5 _SUMMARY_ Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * David Miller wrote: > From: Arnaldo Carvalho de Melo > 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