From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758471AbZBSUwU (ORCPT ); Thu, 19 Feb 2009 15:52:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754182AbZBSUwG (ORCPT ); Thu, 19 Feb 2009 15:52:06 -0500 Received: from terminus.zytor.com ([198.137.202.10]:55882 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753421AbZBSUwE (ORCPT ); Thu, 19 Feb 2009 15:52:04 -0500 Message-ID: <499DC5A6.1080305@zytor.com> Date: Thu, 19 Feb 2009 12:48:38 -0800 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.19 (X11/20090105) MIME-Version: 1.0 To: Jeremy Fitzhardinge CC: Ingo Molnar , Petr Tesarik , LKML Subject: Re: [PATCH] x86: remove unneeded endless loop in BUG() References: <1235068713.15053.99.camel@nathan.suse.cz> <20090219185935.GA21820@elte.hu> <499DB8BA.3050708@zytor.com> <499DC545.2030402@goop.org> In-Reply-To: <499DC545.2030402@goop.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jeremy Fitzhardinge wrote: > > There's no reason to expect an "asm volatile" to stay put; the > "volatile" has nothing to do with preventing code motion. The only way > to make an asm stick in one place is with data dependencies, and I'm not > sure what the dependency for __builtin_trap might be. I'm guessing its > a "memory" clobber, but that's pure guesswork. > I looked through this with HJL; the bottom line is that although it probably would work, it's not worth it. I submitted GCC bug 39252 to get __builtin_not_reached(); instead. -hpa