Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760512AbcCDWx5 (ORCPT ); Fri, 4 Mar 2016 17:53:57 -0500 Received: from mx2.suse.de ([195.135.220.15]:58167 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760316AbcCDWx4 (ORCPT ); Fri, 4 Mar 2016 17:53:56 -0500 Subject: Re: [PATCH v5 5/8] kbuild: add fine grained build dependencies for exported symbols To: Nicolas Pitre References: <1457070050-1564-1-git-send-email-nicolas.pitre@linaro.org> <1457070050-1564-6-git-send-email-nicolas.pitre@linaro.org> <56DA118E.20106@suse.com> Cc: linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org From: Michal Marek Message-ID: <56DA1201.9010605@suse.cz> Date: Fri, 4 Mar 2016 23:53:53 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.0 MIME-Version: 1.0 In-Reply-To: <56DA118E.20106@suse.com> Content-Type: text/plain; charset=iso-8859-2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1163 Lines: 22 Dne 4.3.2016 v 23:51 Michal Marek napsal(a): > Dne 4.3.2016 v 06:40 Nicolas Pitre napsal(a): >> +cmd_and_fixdep = \ >> + $(echo-cmd) $(cmd_$(1)); \ >> + $(ksym_dep_filter) | \ >> + scripts/basic/fixdep -e $(depfile) $@ '$(make-cmd)' \ >> + > $(dot-target).tmp; \ >> + rm -f $(depfile); \ >> + mv -f $(dot-target).tmp $(dot-target).cmd; > > While trying this, I got a SIGBUS from fixdep once. My theory is that > the depfile is mmap()ed by fixdep and modified by the preprocesor run at > the same time. I could not reproduce this so far (still trying). But if > it's really this race, the fix would be to disable dependency generation > in the preprocessor by passing -Wp,MD,/dev/null or somesuch. But we > never had this problem with genksyms, which is weird. It could as well > be that my build machine's memory is faulty :(. Actually, genksyms does not ran in parallel. neither before nor after this patch. Michal