Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751298AbWIUQAT (ORCPT ); Thu, 21 Sep 2006 12:00:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751299AbWIUQAT (ORCPT ); Thu, 21 Sep 2006 12:00:19 -0400 Received: from stat9.steeleye.com ([209.192.50.41]:45749 "EHLO hancock.sc.steeleye.com") by vger.kernel.org with ESMTP id S1751295AbWIUQAR (ORCPT ); Thu, 21 Sep 2006 12:00:17 -0400 Subject: Re: ZONE_DMA (was: Re: 2.6.19 -mm merge plans) From: James Bottomley To: Alan Cox Cc: Christoph Lameter , Andrew Morton , "Martin J. Bligh" , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Christoph Hellwig In-Reply-To: <1158800630.11109.72.camel@localhost.localdomain> References: <20060920135438.d7dd362b.akpm@osdl.org> <4511D855.7050100@mbligh.org> <20060920172253.f6d11445.akpm@osdl.org> <1158800630.11109.72.camel@localhost.localdomain> Content-Type: text/plain Date: Thu, 21 Sep 2006 11:59:51 -0400 Message-Id: <1158854391.14329.1.camel@mulgrave.il.steeleye.com> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-4.fc4) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 612 Lines: 16 On Thu, 2006-09-21 at 02:03 +0100, Alan Cox wrote: > IOMMUs don't always help. They IOMMU aperture on AMD64 for example is > too high to help devices with below 32bit limits. That's because it's not an IOMMU; it's a GART. A true IOMMU separates the machine physical and bus physical address spaces ... a GART merely remaps a hole in physical address space. James - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/