From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754644AbbK0PPJ (ORCPT ); Fri, 27 Nov 2015 10:15:09 -0500 Received: from mail.kernel.org ([198.145.29.136]:40078 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751484AbbK0PPG (ORCPT ); Fri, 27 Nov 2015 10:15:06 -0500 Date: Fri, 27 Nov 2015 12:15:01 -0300 From: Arnaldo Carvalho de Melo To: "Wangnan (F)" Cc: Jiri Olsa , Linux Kernel Mailing List Subject: Re: perf BPF/elfdep intermitent build problems Message-ID: <20151127151501.GC5934@kernel.org> References: <20151118224458.GD22729@kernel.org> <564D24E9.8040208@huawei.com> <564D323A.1050200@huawei.com> <564D33F3.9050004@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <564D33F3.9050004@huawei.com> 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, Nov 19, 2015 at 10:29:07AM +0800, Wangnan (F) escreveu: > On 2015/11/19 10:21, Wangnan (F) wrote: > >On 2015/11/19 9:24, Wangnan (F) wrote: > >>On 2015/11/19 6:44, Arnaldo Carvalho de Melo wrote: > >>>Have you guys ever saw this? > >>> > >>>[acme@zoo linux]$ alias m > >>>alias m='perf stat -e cycles make O=/tmp/build/perf -C tools/perf > >>>install-bin' > >>>[acme @zoo linux]$ m > >>>make: Entering directory '/home/git/linux/tools/perf' > >>> BUILD: Doing 'make -j4' parallel build > >>>make[2]: Nothing to be done for 'fixdep'. > >>> CC /tmp/build/perf/util/machine.o > >>> LD /tmp/build/perf/util/libperf-in.o > >>>No libelf found > >>>BPF API too old > >> > >>This error message means the kernel header in rootfs is too old, > >>causes tools/build/feature/test-bpf.c failed to be built. > > > >Strange... even in feature detection it should check BPF API through > >kernel source where you are using to build perf... > > > >I guess you are not using NFS or share it with other people? Some build problem just happened and your question came to my mind, yeah, sometimes I NFS mount it from a RHEL6 (and other distros) to do 'make -C tools/perf build-test' to check it works with those distros, and I forgot to do a: make -C tools/ clean I guess I'll have to try to make build-test support O=... So that polluting the source tree doesn't causes problems like this. Will try even to make it turn the source tree read only so that we spot when O= is not being honoured... - Arnaldo