From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754207AbYIXM62 (ORCPT ); Wed, 24 Sep 2008 08:58:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751879AbYIXM6U (ORCPT ); Wed, 24 Sep 2008 08:58:20 -0400 Received: from outbound-dub.frontbridge.com ([213.199.154.16]:27221 "EHLO IE1EHSOBE002.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751878AbYIXM6T (ORCPT ); Wed, 24 Sep 2008 08:58:19 -0400 X-BigFish: VPS-28(zz1432R98dR1805M936fOzzzz2f39iz32i6bh43j61h) X-Spam-TCS-SCL: 0:0 X-WSS-ID: 0K7PAOV-03-LIR-01 Date: Wed, 24 Sep 2008 14:58:08 +0200 From: Joerg Roedel To: FUJITA Tomonori CC: mingo@elte.hu, linux-kernel@vger.kernel.org, andi@firstfloor.org Subject: Re: [PATCH 0/3] x86: restore old GART alloc_coherent Message-ID: <20080924125808.GU24392@amd.com> References: <1222256917-14321-1-git-send-email-fujita.tomonori@lab.ntt.co.jp> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <1222256917-14321-1-git-send-email-fujita.tomonori@lab.ntt.co.jp> User-Agent: mutt-ng/devel-r804 (Linux) X-OriginalArrivalTime: 24 Sep 2008 12:58:08.0129 (UTC) FILETIME=[310D1F10:01C91E45] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 24, 2008 at 08:48:34PM +0900, FUJITA Tomonori wrote: > This pachset is against tip/iommu. > > What this patchset does is restoring old GART alloc_coherent behavior > (before the alloc_coherent rewrite): > > http://lkml.org/lkml/2008/8/12/200 > > Currently, GART alloc_coherent tries to allocate pages with GFP_DMA32 > for a device having dma_masks > 24bit < 32bits. If GART gets an > address that a device can't access to, GART tries to map the address > to a virtual I/O address that the device can access to. > > But Andi pointed out, "The GART is somewhere in the 4GB range so you > cannot use it to map anything < 4GB. Also GART is pretty small." > > http://lkml.org/lkml/2008/9/12/43 > > So it's possible that GART doesn't have virtual I/O address space that > a device can access to. The current behavior might not work for a > device having dma_masks > 24bit < 32bits. This patchset restores old > GART alloc_coherent behavior, which doesn't use GART hardware (if an > user doesn't enable force_iommu option). Acked-by: Joerg Roedel -- | AMD Saxony Limited Liability Company & Co. KG Operating | Wilschdorfer Landstr. 101, 01109 Dresden, Germany System | Register Court Dresden: HRA 4896 Research | General Partner authorized to represent: Center | AMD Saxony LLC (Wilmington, Delaware, US) | General Manager of AMD Saxony LLC: Dr. Hans-R. Deppe, Thomas McCoy