From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755891AbYFTTT0 (ORCPT ); Fri, 20 Jun 2008 15:19:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754189AbYFTTSs (ORCPT ); Fri, 20 Jun 2008 15:18:48 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:33904 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753749AbYFTTSm (ORCPT ); Fri, 20 Jun 2008 15:18:42 -0400 Date: Fri, 20 Jun 2008 12:15:24 -0700 (PDT) From: Linus Torvalds To: Jeremy Fitzhardinge cc: Ingo Molnar , benh@kernel.crashing.org, xen-devel , Peter Zijlstra , kvm-devel , x86@kernel.org, LKML , Virtualization Mailing List , Hugh Dickins , Thomas Gleixner Subject: Re: [PATCH 1 of 4] mm: add a ptep_modify_prot transaction abstraction In-Reply-To: <485BFFC4.3070902@goop.org> Message-ID: References: <1213831403.8011.24.camel@pasglop> <4859A149.9090004@goop.org> <4859A528.1010107@goop.org> <4859AA47.2020903@goop.org> <20080619115832.GM15228@elte.hu> <20080619164708.GA32190@elte.hu> <20080620101028.GA23664@elte.hu> <485BFFC4.3070902@goop.org> User-Agent: Alpine 1.10 (LFD 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 20 Jun 2008, Jeremy Fitzhardinge wrote: > > Blows up on "gcc version 3.4.4 20050314 (prerelease) (Debian 3.4.3-13)": Yeah, I was a bit worried about that. Gcc sometimes does insane things. We literally just tested that the asm should only _ever_ be generated with a constant value, but if some gcc dead-code removal thing doesn't work, it will then screw up and try to generate the asm even for a non-constant thing. The fairly trivial fix is probably to just change the "i" to "ir", safe in the knowledge that any _sane_ case will never use the "r" possibility. I suspect even your insane case will end up then killing the bad choice later. Linus