Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932665AbYF0XR1 (ORCPT ); Fri, 27 Jun 2008 19:17:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1764734AbYF0XLQ (ORCPT ); Fri, 27 Jun 2008 19:11:16 -0400 Received: from mail-wa4.bigfish.com ([216.32.181.111]:10202 "EHLO mail26-wa4-R.bigfish.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932170AbYF0XLN convert rfc822-to-8bit (ORCPT ); Fri, 27 Jun 2008 19:11:13 -0400 X-Greylist: delayed 1419 seconds by postgrey-1.27 at vger.kernel.org; Fri, 27 Jun 2008 19:11:13 EDT X-BigFish: VPS-41(zz1432R98dR7efV1805M3117Kzzzzz32i6bh) X-MS-Exchange-Organization-Antispam-Report: OrigIP: 163.181.251.22;Service: EHS X-WSS-ID: 0K358MN-01-32O-01 x-mimeole: Produced By Microsoft Exchange V6.5 Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Subject: RE: [PATCH 01/34] AMD IOMMU: add Kconfig entry Date: Fri, 27 Jun 2008 17:47:56 -0500 Message-ID: <6453C3CB8E2B3646B0D020C1126132730120C4EE@sausexmb4.amd.com> In-Reply-To: <20080627222931.GB7201@il.ibm.com> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [PATCH 01/34] AMD IOMMU: add Kconfig entry Thread-Index: AcjYppi7UCpSKDytRTWVq8Ng/SrZ2wAACW6Q References: <20080627170546.GE10197@8bytes.org> <6453C3CB8E2B3646B0D020C1126132730120C444@sausexmb4.amd.com> <20080627222931.GB7201@il.ibm.com> From: "Duran, Leo" To: "Muli Ben-Yehuda" Cc: "Joerg Roedel" , "Adrian Bunk" , "Richter, Robert" , , , "Andi Kleen" , "Biemueller, Sebastian" , , , "Sarathy, Bhavna" X-OriginalArrivalTime: 27 Jun 2008 22:47:23.0487 (UTC) FILETIME=[C3B8DEF0:01C8D8A7] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1557 Lines: 43 On Friday, June 27, 2008 5:30 PM, Muli Ben-Yehuda 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 Hi Muli, Yes, you could set an exclusion range for addresses about the virtual address space (or 'translation aperture'). I played with that in the context of "dma.ops" (not surprisingly, the exclusion range was pretty busy!). Again, keep in mind: no protection in the exclusion range (sort of defeating the purpose of having an IOMMU in the first place), and only ONE exclusion range per IOMMU. Leo. -- 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/