From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753339AbZG2Jgx (ORCPT ); Wed, 29 Jul 2009 05:36:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751458AbZG2Jgw (ORCPT ); Wed, 29 Jul 2009 05:36:52 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:56751 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751355AbZG2Jgw (ORCPT ); Wed, 29 Jul 2009 05:36:52 -0400 Subject: Re: [RFC] Make AGP work with IOMMU From: David Woodhouse To: Dave Airlie , Keir Fraser , xen-devel@lists.xensource.com Cc: Zhenyu Wang , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Joerg Roedel In-Reply-To: <21d7e9970907290143q6778511cvda1c6b915f61654a@mail.gmail.com> References: <1248707041.6100.35.camel@macbook.infradead.org> <21d7e9970907282328l4a44b9a2of4500c5c84a3586b@mail.gmail.com> <1248851712.19733.214.camel@macbook.infradead.org> <21d7e9970907290143q6778511cvda1c6b915f61654a@mail.gmail.com> Content-Type: text/plain Date: Wed, 29 Jul 2009 10:36:45 +0100 Message-Id: <1248860205.19733.238.camel@macbook.infradead.org> Mime-Version: 1.0 X-Mailer: Evolution 2.26.3 (2.26.3-1.fc11) Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.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 On Wed, 2009-07-29 at 18:43 +1000, Dave Airlie wrote: > >> don't suppose we want page_to_gart or is the double function nicer? > > > > I pondered that briefly. But then observed that phys_to_gart() and > > gart_to_phys() _always_ describe an identity mapping, so perhaps they > > could just be ditched completely? > > Yeah that could work too, no idea why they were introduced, well before my time. http://git.infradead.org/users/dwmw2/iommu-agp.git?a=commitdiff;h=8bf2f3a9 It was introduced by Keir in 2005 for Xen (commit 07eee78e). I suspect it can die though, and that the right answer there is also to use the DMA API correctly. -- David Woodhouse Open Source Technology Centre David.Woodhouse@intel.com Intel Corporation