From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762007AbZEGL0j (ORCPT ); Thu, 7 May 2009 07:26:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754421AbZEGL0a (ORCPT ); Thu, 7 May 2009 07:26:30 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:37483 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753838AbZEGL03 (ORCPT ); Thu, 7 May 2009 07:26:29 -0400 Date: Thu, 7 May 2009 13:26:01 +0200 From: Ingo Molnar To: FUJITA Tomonori Cc: airlied@linux.ie, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, mingo@redhat.com, dwmw2@infradead.org Subject: Re: IOMMU and graphics cards Message-ID: <20090507112601.GJ28398@elte.hu> References: <20090507100114.GF4059@amd.com> <20090507191724N.fujita.tomonori@lab.ntt.co.jp> <20090507110135.GC28398@elte.hu> <20090507201538U.fujita.tomonori@lab.ntt.co.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090507201538U.fujita.tomonori@lab.ntt.co.jp> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * FUJITA Tomonori wrote: > On Thu, 7 May 2009 13:01:35 +0200 > Ingo Molnar wrote: > > > > > * FUJITA Tomonori wrote: > > > > > > The proprietary drivers make problems so far. For the ATI one I > > > > am in contact with the developers to try to fix it. But I can't > > > > do anything about the other proprietary driver I am aware of :-( > > > > > > I don't know anything about the graphic drivers but are there any > > > other proprietary drivers except for ATI and AMD? Fixing only two > > > drivers to make the majority happy? > > > > ATI ~== AMD these days. The problem is Nvidia cards stuck into AMD > > systems. > > Oops, I meant ATI and Nvidia. > > > > I guess refusing those DMA accesses (and printing something > > meaningful and relentlessly honest so that the user knows where the > > problem comes from) is the proper solution. > > Refusing DMA means that we will break these broken drivers. That's > what David and I like. Yeah, telling users explicitly who is to > blame for the problem is even better. If it means a non-working Xorg, then there might be nothing on the screen to report - just a seemingly hung box and people will blame the kernel. It might be better to just turn off all things IOMMU at that point, but still allow things to continue. ... which might break good drivers that relied on the IOMMU sorting out 32-bit DMA space limitations. So it would be nice to make the failure mode somehow nicer. I.e. test how this affects the nvidia driver. Is there something on the screen to see? Could we print an URL to the Noveau driver perhaps too? A bad solution in general is to crash/hang a significant proportion of Linux boxes. That is a foot-in-own-mouth masochistic excercise mostly, it creates a stigma for the IOMMU code, not for nvidia. So the failure mode has to be well thought out. Ingo