From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932319AbWGHJw1 (ORCPT ); Sat, 8 Jul 2006 05:52:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932321AbWGHJw1 (ORCPT ); Sat, 8 Jul 2006 05:52:27 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:57569 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S932319AbWGHJw0 (ORCPT ); Sat, 8 Jul 2006 05:52:26 -0400 Subject: Re: [patch] spinlocks: remove 'volatile' From: Arjan van de Ven To: joe.korty@ccur.com Cc: Albert Cahalan , linux-kernel@vger.kernel.org, Linus Torvalds , linux-os@analogic.com, khc@pm.waw.pl, mingo@elte.hu, akpm@osdl.org In-Reply-To: <20060708094556.GA13254@tsunami.ccur.com> References: <787b0d920607072054i237eebf5g8109a100623a1070@mail.gmail.com> <20060708094556.GA13254@tsunami.ccur.com> Content-Type: text/plain Date: Sat, 08 Jul 2006 11:52:23 +0200 Message-Id: <1152352343.3120.17.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2006-07-08 at 05:45 -0400, Joe Korty wrote: > On Fri, Jul 07, 2006 at 11:54:10PM -0400, Albert Cahalan wrote: > > That's all theoretical though. Today, gcc's volatile does > > not follow the C standard on modern hardware. Bummer. > > It'd be low-performance anyway though. > > But gcc would follow the standard if it emitted a 'lock' > insn on every volatile reference. nope that's not nearly enough for pci MMIO space for example, nor for any of the weakly ordered architectures.