From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161556AbXDYBNO (ORCPT ); Tue, 24 Apr 2007 21:13:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161568AbXDYBNO (ORCPT ); Tue, 24 Apr 2007 21:13:14 -0400 Received: from terminus.zytor.com ([192.83.249.54]:55328 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161562AbXDYBNN (ORCPT ); Tue, 24 Apr 2007 21:13:13 -0400 Message-ID: <462EAB13.4040104@zytor.com> Date: Tue, 24 Apr 2007 18:12:51 -0700 From: "H. Peter Anvin" User-Agent: Thunderbird 1.5.0.10 (X11/20070302) MIME-Version: 1.0 To: Andi Kleen CC: David Miller , ashok.raj@intel.com, 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 Subject: Re: [Intel IOMMU][patch 8/8] Preserve some Virtual Address when devices cannot address entire range. References: <200704242312.54738.ak@suse.de> <20070424213835.GB31920@linux-os.sc.intel.com> <20070424.145026.128110905.davem@davemloft.net> <200704250003.57968.ak@suse.de> In-Reply-To: <200704250003.57968.ak@suse.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andi Kleen wrote: > On Tuesday 24 April 2007 23:50:26 David Miller wrote: >> From: Ashok Raj >> Date: Tue, 24 Apr 2007 14:38:35 -0700 >> >>> Its not clear if we have a very generic device breakage.. most devices >>> on these platforms are going to be more recent, (except maybe some >>> legacy fd)... >> I'm not so sure, there are some "modern" sound cards that have >> a 31-bit DMA addressing limitation because they use the 31st >> bit as a status bit in their DMA descriptors :-) > > There's also a 2GB only megaraid RAID controller that's pretty popular > because Dell shipped it for a long time. > You can probably find almost any possible bitmask if you look long enough. Hardware vendors are notorious for this kind of "optimizations". -hpa