From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757398AbZLFTM4 (ORCPT ); Sun, 6 Dec 2009 14:12:56 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757207AbZLFTMz (ORCPT ); Sun, 6 Dec 2009 14:12:55 -0500 Received: from terminus.zytor.com ([198.137.202.10]:46754 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757193AbZLFTMy (ORCPT ); Sun, 6 Dec 2009 14:12:54 -0500 Message-ID: <4B1C01F4.8020304@zytor.com> Date: Sun, 06 Dec 2009 11:11:48 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.4pre) Gecko/20091014 Fedora/3.0-2.8.b4.fc11 Thunderbird/3.0b4 MIME-Version: 1.0 To: Jiri Slaby CC: mingo@elte.hu, jirislaby@gmail.com, linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , x86@kernel.org Subject: Re: [PATCH 1/1] X86: use explicit register name for get/put_user References: <1260091808-8053-1-git-send-email-jslaby@suse.cz> In-Reply-To: <1260091808-8053-1-git-send-email-jslaby@suse.cz> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/06/2009 01:30 AM, Jiri Slaby wrote: > > I don't know if this could ever cause any problems, but changing > the input to an explicit register ("a") makes it cleaner in my eyes. > There is no need of the back reference. > It can't: the backreference refers to only the information that is in the register constraint, not to anything else. I really would prefer avoiding any changes to working code that aren't justified, simply because every time we change an asm() we risk tickling a new obscure bug in some old version of gcc. As such, Nacked-by: H. Peter Anvin -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.