From mboxrd@z Thu Jan 1 00:00:00 1970 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 Message-ID: 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 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 To: Satyam Sharma Return-path: 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: Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org > #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[It wasn't explained on a GCC list in response to your patch, as far as I can see -- if I missed it, please point me to an archived version of it].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