From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnaldo Carvalho de Melo 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?= Date: Thu, 17 Sep 2015 11:37:08 -0300 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-Transfer-Encoding: QUOTED-PRINTABLE Return-path: 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 Content-Disposition: inline In-Reply-To: <20150917140619.GK11551@kernel.org> Sender: linux-perf-users-owner@vger.kernel.org List-ID: 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 Em Thu, Sep 17, 2015 at 11:06:19AM -0300, Arnaldo Carvalho de Melo escr= eveu: > 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. > > >=20 > > > The following build error occurs on both CentOS 5.11 (elfutils 0.= 137) > > > and Ubuntu 10.04.4 (elfutils 0.143). > > >=20 > > > CC util/symbol-elf.o > > > cc1: warnings being treated as errors > > > util/symbol-elf.c:41: error: no previous prototype for =E2=80=98e= lf_getphdrnum=E2=80=99 > >=20 > > 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. > >=20 > > AFAICT gcc accepts multiple prototypes so long as they are the same > > so just adding the prototype should be ok i.e. >=20 > But that looks like a bandaid :-\ >=20 > The comment I made in f785f2357673d520a0b7b468973cdd197f336494 was no= t > clear enough, now I'm the one trying to figure out why I did that... = Duh > :-\ >=20 > I.e. if: >=20 > "HAVE_ELF_GETPHDRNUM_SUPPORT is false" we shouldn't have any prototyp= e > 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 fail= ed, > 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=20 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-getphdrnu= m.make.output cc1: warnings being treated as errors test-libelf-getphdrnum.c: In function =E2=80=98main=E2=80=99: test-libelf-getphdrnum.c:7: warning: implicit declaration of function= =E2=80=98elf_getphdrnum=E2=80=99 [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