Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932489AbWBYRLt (ORCPT ); Sat, 25 Feb 2006 12:11:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932515AbWBYRLt (ORCPT ); Sat, 25 Feb 2006 12:11:49 -0500 Received: from mx.pathscale.com ([64.160.42.68]:46309 "EHLO mx.pathscale.com") by vger.kernel.org with ESMTP id S932489AbWBYRLs (ORCPT ); Sat, 25 Feb 2006 12:11:48 -0500 Subject: Re: [PATCH] Define wc_wmb, a write barrier for PCI write combining From: "Bryan O'Sullivan" To: Benjamin LaHaise Cc: Andrew Morton , Andi Kleen , linux-kernel In-Reply-To: <20060225142814.GB17844@kvack.org> References: <1140841250.2587.33.camel@localhost.localdomain> <20060225142814.GB17844@kvack.org> Content-Type: text/plain Date: Sat, 25 Feb 2006 09:11:57 -0800 Message-Id: <1140887517.9852.4.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.5.90 (2.5.90-2.1) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 584 Lines: 16 On Sat, 2006-02-25 at 09:28 -0500, Benjamin LaHaise wrote: > sfence has no impact > on the flushing of the write combining buffers The sfence instruction guarantees that every store that precedes it in program order is globally visible, including over the likes of the PCI bus, before any store instruction that follows the fence.