Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751351AbWILG3R (ORCPT ); Tue, 12 Sep 2006 02:29:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751352AbWILG3R (ORCPT ); Tue, 12 Sep 2006 02:29:17 -0400 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:59837 "EHLO ebiederm.dsl.xmission.com") by vger.kernel.org with ESMTP id S1751351AbWILG3Q (ORCPT ); Tue, 12 Sep 2006 02:29:16 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Benjamin Herrenschmidt Cc: Alan Cox , Linux Kernel list , Jesse Barnes , "David S. Miller" , Jeff Garzik , Paul Mackerras , Linus Torvalds , Andrew Morton , Segher Boessenkool Subject: Re: [RFC] MMIO accessors & barriers documentation References: <1157947414.31071.386.camel@localhost.localdomain> <1157965071.23085.84.camel@localhost.localdomain> <1157966269.3879.23.camel@localhost.localdomain> <1157969261.23085.108.camel@localhost.localdomain> <1158040605.15465.70.camel@localhost.localdomain> Date: Tue, 12 Sep 2006 00:27:57 -0600 In-Reply-To: <1158040605.15465.70.camel@localhost.localdomain> (Benjamin Herrenschmidt's message of "Tue, 12 Sep 2006 15:56:45 +1000") Message-ID: User-Agent: Gnus/5.110004 (No Gnus v0.4) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1123 Lines: 26 Benjamin Herrenschmidt writes: > I've not gone too much in details about write combining (we need to do > something about it but I don't want to mix problems) but I did define > that the ordered accessors aren't guaranteed to provide write combining > on storage mapped with WC enabled while the relaxed or non ordered ones > are. That should be enough at this point. Sounds good. > Later, we should look into providing an ioremap_wc() and possibly page > table flags for write combining userland mappings. Time to get rid of > MTRRs for graphics :) And infiniband-style stuff seems to want that too. ioremap_wc is actually the easy half. I have an old patch that handles that. The trick is to make certain multiple people don't map the same thing with different attributes. Unfortunately I haven't had time to work through that one yet. Eric - 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/