From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753536AbYIVQbl (ORCPT ); Mon, 22 Sep 2008 12:31:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751334AbYIVQbe (ORCPT ); Mon, 22 Sep 2008 12:31:34 -0400 Received: from outbound-sin.frontbridge.com ([207.46.51.80]:46692 "EHLO SG2EHSOBE006.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751287AbYIVQbd (ORCPT ); Mon, 22 Sep 2008 12:31:33 -0400 X-BigFish: VPS-30(zz1432R98dR1805M936fQzz10d3izzz32i6bh43j62h) X-Spam-TCS-SCL: 1:0 X-WSS-ID: 0K7LV7T-04-1CR-01 Date: Mon, 22 Sep 2008 18:31:09 +0200 From: Joerg Roedel To: FUJITA Tomonori CC: mingo@elte.hu, linux-kernel@vger.kernel.org Subject: Re: [PATCH] AMD IOMMU: revert "x86, AMD IOMMU: honor iommu=off instead of amd_iommu=off" Message-ID: <20080922163109.GD24392@amd.com> References: <20080922140749.GY24392@amd.com> <20080922231619X.fujita.tomonori@lab.ntt.co.jp> <20080922142713.GA24392@amd.com> <20080922235421A.fujita.tomonori@lab.ntt.co.jp> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20080922235421A.fujita.tomonori@lab.ntt.co.jp> User-Agent: mutt-ng/devel-r804 (Linux) X-OriginalArrivalTime: 22 Sep 2008 16:31:09.0654 (UTC) FILETIME=[9E9B8F60:01C91CD0] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 23, 2008 at 12:25:23AM +0900, FUJITA Tomonori wrote: > I don't think that users need to have iommu=calgary parameter to use > calgary IOMMU by default. If you enable CONFIG_CALGARY_IOMMU, > CALGARY_IOMMU_ENABLED_BY_DEFAULT is also enabled by default. If a > kernel finds calgary IOMMU, the kernel uses it by default. > > It's also consistent with how SWIOTLB. Users don't need iommu=soft > parameter to enable SWIOTLB. A kernel enables SWIOTLB automatically > when necessary. Yes. The parameters are usefull if a user wants to enable a specific IOMMU implementation. The user could be an IOMMU developer testing changes in a special implementation the kernel would not choose by default on his machine. I like Ingo's idea here. Lets do boths, implementing iommu=$type to force a specific iommu implementation and $(type)_iommu=off to disable one. > Well, this is the problem about the IOMMUs parameters. The IOMMUs > parameters are too complicated for everyone. Not so complicated that they can't be understood. But if you have a proposal how the command line parameters for iommus may look like, send it. I like join that discussion about the interface. Joerg -- | AMD Saxony Limited Liability Company & Co. KG Operating | Wilschdorfer Landstr. 101, 01109 Dresden, Germany System | Register Court Dresden: HRA 4896 Research | General Partner authorized to represent: Center | AMD Saxony LLC (Wilmington, Delaware, US) | General Manager of AMD Saxony LLC: Dr. Hans-R. Deppe, Thomas McCoy