From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752373Ab3FWUjF (ORCPT ); Sun, 23 Jun 2013 16:39:05 -0400 Received: from terminus.zytor.com ([198.137.202.10]:42857 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751880Ab3FWUjD (ORCPT ); Sun, 23 Jun 2013 16:39:03 -0400 Message-ID: <51C75CD6.5010206@zytor.com> Date: Sun, 23 Jun 2013 13:38:46 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130514 Thunderbird/17.0.6 MIME-Version: 1.0 To: Dave Airlie CC: Henrique de Moraes Holschuh , Brice Goglin , Linux Kernel Mailing List , David Airlie , dri-devel@lists.freedesktop.org, Andy Lutomirski Subject: Re: MTRR use in drivers References: <51C3DDFA.7050204@zytor.com> <51C69732.1010906@gmail.com> <20130623192936.GA28655@khazad-dum.debian.net> <51C75465.9060007@zytor.com> In-Reply-To: X-Enigmail-Version: 1.5.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/23/2013 01:30 PM, Dave Airlie wrote: >>>> Why do you care about performance when PAT is disabled? > > breaking old boxes just because, is just going to get reverted when I > get the first regression report that you broke old boxes. > Not "just because", but *if* the choice is between breaking old boxes and breaking new boxes I'll take the latter. > Andy Lutomirski just submitted a bunch of patches to clean up the DRM > usage of mtrrs, they are in drm-next, afaik we no longer add them on > PAT systems. Fantastic news. No issue, then, and no need to break anything. The only problem I see with having ioremap_wc() installing an MTRR on non-PAT, rather than pushing that into the drivers which is clearly not the right thing, is that we will need a hook to uninstall it when the mapping is destroyed. -hpa