From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753206AbYI3LD7 (ORCPT ); Tue, 30 Sep 2008 07:03:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752476AbYI3LDv (ORCPT ); Tue, 30 Sep 2008 07:03:51 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:42916 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752424AbYI3LDu (ORCPT ); Tue, 30 Sep 2008 07:03:50 -0400 Date: Tue, 30 Sep 2008 13:03:19 +0200 From: Ingo Molnar To: FUJITA Tomonori Cc: joerg.roedel@amd.com, mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/3] x86/iommu: use __GFP_ZERO instead of memset for GART Message-ID: <20080930110319.GA12529@elte.hu> References: <20080927181855.GA11147@elte.hu> <20080928193436.GA8386@amd.com> <20080929085647.GB2190@elte.hu> <20080929231116Q.fujita.tomonori@lab.ntt.co.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080929231116Q.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=3.2.3 -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: > > yes - could you please make a new option for it, > > CONFIG_IOMMU_DEBUG_FORCE=y or so - and cover all iommus that support > > it? > > I'm not sure we are talking about the same thing. Surely, I and Joerg > are talking different things. > > GART driver doesn't need to use the IOMMU hardware at all times. GART > does a virtual mapping only when necessary (a device needs to handle > an address that it can't access to). But as I wrote, if you use > iommu=force, GART driver always use the IOMMU hardware. yes - but iommu=force is not randconfig covered, hence it never gets tested by -tip testing. So my suggestion was a really simple patch: a new Kconfig entry that makes iommu=force default. CONFIG_BOOTPARAM_IOMMU_FORCE=y would be the right name for it. (disabled by default, of course) > Other x86 IOMMU drivers always use the IOMMU hardware. Except for > Intel VT-D, they manage free virtual I/O space in the round-robin > manner with the bitmap algorithm to avoid frequent IOTLB flush. Joerg > said he tested AMD IOMMU driver with the round-robin manner disabled > so AMD IOMMU driver uses the same virtual I/O space with lots of IOTLB > flush. all i'm suggesting is to please expose existing debug capabilities in the .config space, so that it can be tested in automated setups. Ingo