Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753950AbbDHNTe (ORCPT ); Wed, 8 Apr 2015 09:19:34 -0400 Received: from mail-wi0-f178.google.com ([209.85.212.178]:38361 "EHLO mail-wi0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753343AbbDHNTc (ORCPT ); Wed, 8 Apr 2015 09:19:32 -0400 MIME-Version: 1.0 In-Reply-To: <552519AF.1060201@gmail.com> References: <1428388995.3152.10.camel@gmail.com> <1428401356.3152.38.camel@gmail.com> <55241C51.8040107@gmail.com> <552519AF.1060201@gmail.com> From: Pengfei Yuan <0xcoolypf@gmail.com> Date: Wed, 8 Apr 2015 21:19:11 +0800 Message-ID: Subject: Re: Why not build kernel with -O3 To: Austin S Hemmelgarn Cc: Mike Galbraith , linux-kernel@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 955 Lines: 19 2015-04-08 20:06 GMT+08:00 Austin S Hemmelgarn : > I can't remember any off the top of my head, but it does say explicitly in > the GCC manual to be careful with -O3. IIRC, most of the issues relate to > -O3 enabling -ffast-math (which tends to really mess with code that expects > strict IEEE 754 compliance), so it may not be as much of an issue for kernel > code. You might look into some of the projects that use -O3 by default (I > think most of the Mozilla so0ftware does these days, and I know that there > are others, I just can't remember what right now). > I am afraid you are talking about -Ofast, not -O3. See https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html Yuan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/