Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759902AbXHQWuh (ORCPT ); Fri, 17 Aug 2007 18:50:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755015AbXHQWu1 (ORCPT ); Fri, 17 Aug 2007 18:50:27 -0400 Received: from gate.crashing.org ([63.228.1.57]:33158 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754478AbXHQWu0 (ORCPT ); Fri, 17 Aug 2007 18:50:26 -0400 In-Reply-To: References: <46C32618.2080108@redhat.com> <20070815234021.GA28775@gondor.apana.org.au> <3694fb2e4ed1e4d9bf873c0d050c911e@kernel.crashing.org> <46C3B50E.7010702@yahoo.com.au> <194369f4c96ea0e24decf8f9197d5bad@kernel.crashing.org> <46C505B2.6030704@yahoo.com.au> <18117.4848.695269.72976@cargo.ozlabs.ibm.com> Mime-Version: 1.0 (Apple Message framework v623) Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: Content-Transfer-Encoding: 7bit Cc: Paul Mackerras , heiko.carstens@de.ibm.com, horms@verge.net.au, Linux Kernel Mailing List , rpjday@mindspring.com, ak@suse.de, netdev@vger.kernel.org, cfriesen@nortel.com, Nick Piggin , linux-arch@vger.kernel.org, jesper.juhl@gmail.com, Andrew Morton , zlynx@acm.org, clameter@sgi.com, schwidefsky@de.ibm.com, Chris Snook , Herbert Xu , davem@davemloft.net, Linus Torvalds , wensong@linux-vs.org, wjiang@resilience.com From: Segher Boessenkool Subject: Re: [PATCH 0/24] make atomic_read() behave consistently across all architectures Date: Sat, 18 Aug 2007 00:49:08 +0200 To: Satyam Sharma X-Mailer: Apple Mail (2.623) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 891 Lines: 24 > #define forget(a) __asm__ __volatile__ ("" :"=m" (a) :"m" (a)) > > [ This is exactly equivalent to using "+m" in the constraints, as > recently > explained on a GCC list somewhere, in response to the patch in my > bitops > series a few weeks back where I thought "+m" was bogus. ] [It wasn't explained on a GCC list in response to your patch, as far as I can see -- if I missed it, please point me to an archived version of it]. One last time: it isn't equivalent on older (but still supported by Linux) versions of GCC. Current versions of GCC allow it, but it has no documented behaviour at all, so use it at your own risk. Segher - 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/