From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx3.mail.elte.hu ([157.181.1.138]:58796 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751984Ab1CIPLt (ORCPT ); Wed, 9 Mar 2011 10:11:49 -0500 Date: Wed, 9 Mar 2011 16:11:34 +0100 From: Ingo Molnar Subject: Re: [PATCH -v5] kbuild: Add extra gcc checks Message-ID: <20110309151134.GA15730@elte.hu> References: <20110301083529.GA767@liondog.tnic> <20110309144504.GA1096@sepie.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110309144504.GA1096@sepie.suse.cz> Sender: linux-kbuild-owner@vger.kernel.org List-ID: To: Michal Marek Cc: Borislav Petkov , Arnd Bergmann , Sam Ravnborg , torvalds@linux-foundation.org, x86@kernel.org, linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, bp@amd64.org * Michal Marek wrote: > On Tue, Mar 01, 2011 at 09:35:29AM +0100, Borislav Petkov wrote: > > Add a 'W=1' Makefile switch which adds additional checking per build > > object. > > > > The idea behind this option is targeted at developers who, in the > > process of writing their code, want to do the occasional > > > > make W=1 [target.o] > > > > and let gcc do more extensive code checking for them. Then, they > > could eyeball the output for valid gcc warnings about various > > bugs/discrepancies which are not reported during the normal build > > process. > > > > For more background information and a use case, read through this > > thread: http://marc.info/?l=kernel-janitors&m=129802065918147&w=2 > > > > -v5: Document internal kbuild variable which is introduced by this. > > Simplify assignment. > > Thanks, applied to kbuild-2.6.git#packaging. If someone comes up with a > good selection of warnings for W=1 and W=2, we can change it later. Another, related, very nice kbuild feature would be to allow for arch maintainers to mark certain files as "should only build fine without warnings" - i.e. -Werror should be the default. There would be a Kconfig feature to opt out of this, CONFIG_CC_IGNORE_WARNINGS=y or so. This would allow for people to still build the kernel with old (or buggy) versions of GCC. arch/x86/ would start using this by gradually marking more and more files as -Werror by default. Some architectures like arch/sparc/ and arch/powerpc/ already build with -Werror enabled - but for arch/x86/ we cannot force this (we cannot break the build for who knows how many people) so we want to do it gradually and with a way out for users with buggy compilers. Thanks, Ingo