From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756591AbZGGI7T (ORCPT ); Tue, 7 Jul 2009 04:59:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753799AbZGGI7M (ORCPT ); Tue, 7 Jul 2009 04:59:12 -0400 Received: from tx2ehsobe003.messaging.microsoft.com ([65.55.88.13]:27304 "EHLO TX2EHSOBE005.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754665AbZGGI7L convert rfc822-to-8bit (ORCPT ); Tue, 7 Jul 2009 04:59:11 -0400 X-SpamScore: -23 X-BigFish: VPS-23(zz1432R98dN936eM1805Mzz1202hzzz32i6bh43j62h) X-Spam-TCS-SCL: 1:0 X-FB-SS: 5, X-WSS-ID: 0KMEMAH-01-QRV-01 Date: Tue, 7 Jul 2009 10:59:04 +0200 From: Joerg Roedel To: Dave Airlie CC: David Woodhouse , Joerg Roedel , Zhenyu Wang , linux-kernel@vger.kernel.org, fujita.tomonori@lab.ntt.co.jp, iommu@lists.linux-foundation.org, mingo@redhat.com, David Miller , eric@anholt.net Subject: Re: IOMMU and graphics cards Message-ID: <20090707085904.GP5380@amd.com> References: <20090507164742V.fujita.tomonori@lab.ntt.co.jp> <20090507100114.GF4059@amd.com> <1241691721.3531.73.camel@macbook.infradead.org> <20090507.113632.210373283.davem@davemloft.net> <20090508093526.GB13708@8bytes.org> <1246883177.2615.33.camel@macbook.infradead.org> <20090706131156.GL5380@amd.com> <1246889932.2615.81.camel@macbook.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Content-Transfer-Encoding: 8BIT X-OriginalArrivalTime: 07 Jul 2009 08:59:04.0578 (UTC) FILETIME=[2DC56E20:01C9FEE1] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 06, 2009 at 10:35:59PM +0100, Dave Airlie wrote: > > > On Mon, 6 Jul 2009, David Woodhouse wrote: > > > On Mon, 2009-07-06 at 15:11 +0200, Joerg Roedel wrote: > > > Ok, cool, that sounds good. Which in-kernel DRM drivers break with IOMMU > > > for you? I'll may probably add a similar temporary workaround for AMD > > > IOMMU too... > > > > The Intel one definitely broke -- I don't know about the others. There > > are some old patches at http://people.freedesktop.org/~zhen/agp-mm-* > > which make it look like _all_ AGP drivers are broken. > > > > I wouldn't bother adding the workaround -- as I said, I'm planning to > > rip it out of 2.6.32 (and in linux-next as soon as it's reasonable to do > > so). Let's just let them fix it. > > cc'ing Eric, > > My memory of this is graphics becomes totally useless and can be 10x-50x > slower. I think ripping this out without the person doing the ripping > taking responsiblity for doing speed regression testing is totally insane. Are you sure that using the dma-api has such an performance impact? I've heard from other people that switching to dma-api with amd iommu had no significant performance impact. > I personally have no IOMMU hw from Intel or AMD and nobody has seen it fit > to supply me with any at any point in time, I'm not on the correct gravy > train. So I suspect the people with the hw will have to do the work and > the regression testing. You just need to switch to dma-api. You don't need an iommu to test. Most bugs in such code can also be found and eliminated using the dma-api debugging interface. Joerg -- | Advanced Micro Devices GmbH Operating | Karl-Hammerschmidt-Str. 34, 85609 Dornach bei München System | Research | Geschäftsführer: Thomas M. McCoy, Giuliano Meroni Center | Sitz: Dornach, Gemeinde Aschheim, Landkreis München | Registergericht München, HRB Nr. 43632