Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764029AbYF0Wiv (ORCPT ); Fri, 27 Jun 2008 18:38:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758179AbYF0Win (ORCPT ); Fri, 27 Jun 2008 18:38:43 -0400 Received: from mtagate2.de.ibm.com ([195.212.29.151]:40329 "EHLO mtagate2.de.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750882AbYF0Win (ORCPT ); Fri, 27 Jun 2008 18:38:43 -0400 Date: Fri, 27 Jun 2008 18:29:31 -0400 From: Muli Ben-Yehuda To: "Duran, Leo" Cc: Joerg Roedel , Adrian Bunk , "Richter, Robert" , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Andi Kleen , "Biemueller, Sebastian" , tglx@linutronix.de, mingo@redhat.com, "Sarathy, Bhavna" Subject: Re: [PATCH 01/34] AMD IOMMU: add Kconfig entry Message-ID: <20080627222931.GB7201@il.ibm.com> References: <20080627170546.GE10197@8bytes.org> <6453C3CB8E2B3646B0D020C1126132730120C444@sausexmb4.amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6453C3CB8E2B3646B0D020C1126132730120C444@sausexmb4.amd.com> User-Agent: Mutt/1.5.15+20070412 (2007-04-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1112 Lines: 24 On Fri, Jun 27, 2008 at 03:39:31PM -0500, Duran, Leo wrote: > 2) IOMMU will not translate if the exclusion range has been enabled, and > the DMA address falls inside that range. > The exclusion range can be enabled for specific devices, or for all > devices... Enabling the exclusion range can be considered a 'performance > optimization' (no table-walks), with the caveat of not being able to > provide protection for devices sharing the exclusion range (BTW, there's > a single exclusion address range per IOMMU). So, if I understand this correctly, could we implement Joerg's "almost-direct-map" by having 0-64MB translated for host-owned devices, and then 64MB-end excluded (again, for host-owned devices only)? If yes, it should provide a small boost in performance (may or may not be measurable) over having 64MB-end be an identity translation. Cheers, Muli -- 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/