Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757273AbYFYEuT (ORCPT ); Wed, 25 Jun 2008 00:50:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759909AbYFYEpG (ORCPT ); Wed, 25 Jun 2008 00:45:06 -0400 Received: from casper.infradead.org ([85.118.1.10]:32926 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758855AbYFYEpF (ORCPT ); Wed, 25 Jun 2008 00:45:05 -0400 Date: Tue, 24 Jun 2008 21:44:41 -0700 From: Arjan van de Ven To: Jeremy Fitzhardinge Cc: Ingo Molnar , LKML , x86@kernel.org, xen-devel , Stephen Tweedie , Eduardo Habkost , Mark McLoughlin Subject: Re: [PATCH 03 of 36] x86: add memory barriers to wrmsr Message-ID: <20080624214441.13202f12@infradead.org> In-Reply-To: <93c7057b1f4acae501b2.1214367539@localhost> References: <93c7057b1f4acae501b2.1214367539@localhost> Organization: Intel X-Mailer: Claws Mail 3.3.1 (GTK+ 2.12.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 892 Lines: 22 On Wed, 25 Jun 2008 00:18:59 -0400 Jeremy Fitzhardinge wrote: > wrmsr is a special instruction which can have arbitrary system-wide > effects. We don't want the compiler to reorder it with respect to > memory operations, so make it a memory barrier. it's more readable for several of these cases to stick a barrier(); in front and after it to be honest; that makes it more explicit that these are deliberate compiler barriers rather than "actual" memory access... -- If you want to reach me at my work email, use arjan@linux.intel.com For development, discussion and tips for power savings, visit http://www.lesswatts.org -- 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/