From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965271AbXDXVNH (ORCPT ); Tue, 24 Apr 2007 17:13:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965336AbXDXVNH (ORCPT ); Tue, 24 Apr 2007 17:13:07 -0400 Received: from mx2.suse.de ([195.135.220.15]:53103 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965271AbXDXVNE (ORCPT ); Tue, 24 Apr 2007 17:13:04 -0400 From: Andi Kleen Organization: SUSE Linux Products GmbH, Nuernberg, GF: Markus Rex, HRB 16746 (AG Nuernberg) To: Ashok Raj Subject: Re: [Intel IOMMU][patch 8/8] Preserve some Virtual Address when devices cannot address entire range. Date: Tue, 24 Apr 2007 23:12:54 +0200 User-Agent: KMail/1.9.6 Cc: linux-kernel@vger.kernel.org, akpm@osdl.org, gregkh@suse.de, muli@il.ibm.com, asit.k.mallick@intel.com, suresh.b.siddha@intel.com, anil.s.keshavamurthy@intel.com, arjan@linux.intel.com, shaohua.li@intel.com References: <20070424060259.426374000@intel.com> <200704242133.16219.ak@suse.de> <20070424203304.GB27911@linux-os.sc.intel.com> In-Reply-To: <20070424203304.GB27911@linux-os.sc.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200704242312.54738.ak@suse.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 24 April 2007 22:33:04 Ashok Raj wrote: > With PCIE there is some benefit to keep dma addr low for performance reasons, > since it will use 32bit Transaction level packets instead of 64bit. > > This reservation is only required if we have some legacy device under a p2p > where its required to share its addr space with other devices. We could > implement a default when one is not specified to keep things simple. We already have a couple of other IOMMU architectures who essentially have the same problem. Have you checked how they solve this? -Andi