From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751477AbbIQOhP (ORCPT ); Thu, 17 Sep 2015 10:37:15 -0400 Received: from mail.kernel.org ([198.145.29.136]:34985 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750792AbbIQOhM (ORCPT ); Thu, 17 Sep 2015 10:37:12 -0400 Date: Thu, 17 Sep 2015 11:37:08 -0300 From: Arnaldo Carvalho de Melo To: Adrian Hunter Cc: Vinson Lee , Peter Zijlstra , Ingo Molnar , Namhyung Kim , Jiri Olsa , "Naveen N. Rao" , Srikar Dronamraju , Wang Nan , Victor Kamensky , LKML , linux-perf-users@vger.kernel.org Subject: Re: Linux 4.3-rc1 build error =?utf-8?Q?wi?= =?utf-8?Q?th_older_elfutils_=22util=2Fsymbol-elf=2Ec=3A41=3A5=3A_error=3A?= =?utf-8?Q?_no_previous_prototype_for_=E2=80=98elf=5Fgetphdrnum=E2=80=99?= =?utf-8?Q?=22?= Message-ID: <20150917143708.GL11551@kernel.org> References: <55FA5D8F.6000502@intel.com> <20150917140619.GK11551@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20150917140619.GK11551@kernel.org> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Thu, Sep 17, 2015 at 11:06:19AM -0300, Arnaldo Carvalho de Melo escreveu: > Em Thu, Sep 17, 2015 at 09:28:31AM +0300, Adrian Hunter escreveu: > > On 17/09/15 01:10, Vinson Lee wrote: > > > With Linux 4.3-rc1 I get a perf build error using toolchains with > > > older elfutils. > > > > > > The following build error occurs on both CentOS 5.11 (elfutils 0.137) > > > and Ubuntu 10.04.4 (elfutils 0.143). > > > > > > CC util/symbol-elf.o > > > cc1: warnings being treated as errors > > > util/symbol-elf.c:41: error: no previous prototype for ‘elf_getphdrnum’ > > > > commit f785f2357673d520a0b7b468973cdd197f336494 > > removed the 'static' qualifier, presumably because there > > are cases where the prototype is in the header but the function is > > not in the library. > > > > AFAICT gcc accepts multiple prototypes so long as they are the same > > so just adding the prototype should be ok i.e. > > But that looks like a bandaid :-\ > > The comment I made in f785f2357673d520a0b7b468973cdd197f336494 was not > clear enough, now I'm the one trying to figure out why I did that... Duh > :-\ > > I.e. if: > > "HAVE_ELF_GETPHDRNUM_SUPPORT is false" we shouldn't have any prototype > for that elf_getphdrnum function, i.e. the fact that it is in libelf.h > should mean that it is present, how come the feature test for it failed, > i.e. HAVE_ELF_GETPHDRNUM_SUPPORT wasn't defined? So, on RHEL5.11 (aka, I guess, CentOS 5.11): [acme@rhel5 linux]$ cat /etc/redhat-release Red Hat Enterprise Linux Server release 5.11 (Tikanga) [acme@rhel5 linux]$ rpm -q elfutils elfutils-0.137-3.el5 [acme@rhel5 linux]$ cat /tmp/build/perf/feature/test-libelf-getphdrnum.make.output cc1: warnings being treated as errors test-libelf-getphdrnum.c: In function ‘main’: test-libelf-getphdrnum.c:7: warning: implicit declaration of function ‘elf_getphdrnum’ [acme@rhel5 linux]$ If I revert my patch, it builds... I am now building this in more systems while trying to get my head around how HAVE_ELF_GETPHDRNUM_SUPPORT can be false while elf_getphdrnum() is defined. - Arnaldo