From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757473AbYEOJbX (ORCPT ); Thu, 15 May 2008 05:31:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752218AbYEOJbP (ORCPT ); Thu, 15 May 2008 05:31:15 -0400 Received: from one.firstfloor.org ([213.235.205.2]:36553 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752685AbYEOJbO (ORCPT ); Thu, 15 May 2008 05:31:14 -0400 Message-ID: <482C02A4.80101@firstfloor.org> Date: Thu, 15 May 2008 11:30:12 +0200 From: Andi Kleen User-Agent: Thunderbird 2.0.0.6 (X11/20070801) MIME-Version: 1.0 To: FUJITA Tomonori CC: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, muli@il.ibm.com, alexisb@us.ibm.com Subject: Re: [PATCH 0/2] x86: per-device dma_mapping_ops References: <1210658692-960-1-git-send-email-fujita.tomonori@lab.ntt.co.jp> <87y76cym96.fsf@basil.nowhere.org> <20080515181619R.tomof@acm.org> In-Reply-To: <20080515181619R.tomof@acm.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org FUJITA Tomonori wrote: > On Thu, 15 May 2008 11:01:09 +0200 > Andi Kleen wrote: > >> FUJITA Tomonori writes: >> >>> This patchset adds per-device dma_mapping_ops support for >>> CONFIG_X86_64 like POWER architecture does. This change enables us to >>> cleanly fix the Calgary IOMMU issue that some devices are not behind >>> the IOMMU [1]. It also would be helpful to handle KVM PCI passthrough. >> This makes it basically impossible to do stack ops, which some >> people have been doing. > > Seems that I misunderstand what those people want. > > What those people want to do and how the stack ops achieve it? Or can > you tell me where their patches are? I've seen it in two cases: first was for KVM IO bypass and the other was a (unfinished) patch to support the NoDMA bitmaps on some systems. In this case you really want to do a wrapper around the existing ops and extend the mapping. That worked fine by just replacing the global pointer, but will be quite hard in your set up. -Andi