From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756444AbYESGeB (ORCPT ); Mon, 19 May 2008 02:34:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754774AbYESGdd (ORCPT ); Mon, 19 May 2008 02:33:33 -0400 Received: from mo10.iij4u.or.jp ([210.138.174.78]:53203 "EHLO mo10.iij4u.or.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750716AbYESGd2 (ORCPT ); Mon, 19 May 2008 02:33:28 -0400 Date: Mon, 19 May 2008 15:32:10 +0900 To: andi@firstfloor.org Cc: fujita.tomonori@lab.ntt.co.jp, 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 From: FUJITA Tomonori In-Reply-To: <482D1A91.3050803@firstfloor.org> References: <482C14E4.9050201@firstfloor.org> <20080516124446B.tomof@acm.org> <482D1A91.3050803@firstfloor.org> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-Id: <20080519142352J.tomof@acm.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 16 May 2008 07:24:33 +0200 Andi Kleen wrote: > FUJITA Tomonori wrote: > > On Thu, 15 May 2008 12:48:04 +0200 > > Andi Kleen wrote: > > > >>> I thought that KVM people want to do it per device (in the first > >>> case). So with my patchse, they can replace the dma_ops pointer in > >>> dev_archdata with what they want. > >> But where would they save the original pointer? > > > > Yeah, we need an extra mechanism for that but it's same for the > > system-wide dma_ops pointer (i.e. without my patches), isn't it? > > > > I'm still not sure how this patchset make it impossible to have stack > > dma_ops. These people need per-device dma_ops and we can do stack > > per-device dma_ops? > > Anybody who does stack ops in your scheme would need to hook into new > device creation and an own per device saving pointer. Also there > are livetime issues when to wrap. But is that what those people want, setting up dma_ops per device? I think that creating a hook is not difficult and we could put a mechnism to save a pointer in asm-x86/{dma-mapping.h, device.h}. > It's certainly possible, but likely complicated Hmm, let's see what those people think about on this. I'll repost a patchset for -mm with CC'ing those people.