From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751274AbaKJGdO (ORCPT ); Mon, 10 Nov 2014 01:33:14 -0500 Received: from LGEMRELSE6Q.lge.com ([156.147.1.121]:37988 "EHLO lgemrelse6q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750790AbaKJGdN (ORCPT ); Mon, 10 Nov 2014 01:33:13 -0500 X-Original-SENDERIP: 10.177.222.235 X-Original-MAILFROM: namhyung@gmail.com From: Namhyung Kim To: Peter Zijlstra Cc: Arnaldo Carvalho de Melo , Ingo Molnar , Paul Mackerras , Namhyung Kim , LKML , Jiri Olsa , Adrian Hunter , David Ahern Subject: Re: [PATCH 1/3] perf tools: Allow vmlinux to fallback to kallsyms on NO_LIBELF=1 References: <1415337606-2186-1-git-send-email-namhyung@kernel.org> <20141107082723.GB23531@worktop.programming.kicks-ass.net> <1415372259.1648.51.camel@leonhard> <20141107173718.GD29390@twins.programming.kicks-ass.net> Date: Mon, 10 Nov 2014 15:33:11 +0900 In-Reply-To: <20141107173718.GD29390@twins.programming.kicks-ass.net> (Peter Zijlstra's message of "Fri, 7 Nov 2014 18:37:18 +0100") Message-ID: <87mw7zva3c.fsf@sejong.aot.lge.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Peter, On Fri, 7 Nov 2014 18:37:18 +0100, Peter Zijlstra wrote: > On Fri, Nov 07, 2014 at 11:57:39PM +0900, Namhyung Kim wrote: > >> > Why does this live in the minimal implementation; should we not always >> > discard ELF files with 0 symbols? >> > >> > Suppose I have a vmlinux but removed all symbols from it; I want it to >> > fall back to kallsyms too. >> >> I'm not sure I understood what you said correctly. With this change, >> dso__load_kernel_sym() always ends up calling dso__load_kallsyms() since >> dso__load_vmlinux() will always return 0; >> >> So I think you'll fall back to kallsyms even though you have a vmlinux >> with symbol. This makes dso__load_sym() in the patch 2/3 simpler IMHO. > > But why have it specific to the minimal elf thing? Why not discard any > DSO with 0 symbols and try the next option to acquire symbols? Hmm.. I don't think it's specific to the minimal elf parser. The return value of dso__load_sym() is a number of symbols found so when it sees a dso with 0 symbols it'll fall back to the next option IMHO (not tested). Did you see a problem with the current code? Thanks, Namhyung