Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752067Ab0GMGAx (ORCPT ); Tue, 13 Jul 2010 02:00:53 -0400 Received: from sh.osrg.net ([192.16.179.4]:55858 "EHLO sh.osrg.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751032Ab0GMGAv (ORCPT ); Tue, 13 Jul 2010 02:00:51 -0400 Date: Tue, 13 Jul 2010 14:59:08 +0900 To: zpfeffer@codeaurora.org Cc: joro@8bytes.org, dwalker@codeaurora.org, andi@firstfloor.org, randy.dunlap@oracle.com, mel@csn.ul.ie, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [RFC 3/3] mm: iommu: The Virtual Contiguous Memory Manager From: FUJITA Tomonori In-Reply-To: <4C3BFDD3.8040209@codeaurora.org> References: <4C2D965F.5000206@codeaurora.org> <20100710145639.GC10080@8bytes.org> <4C3BFDD3.8040209@codeaurora.org> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-Id: <20100713145852C.fujita.tomonori@lab.ntt.co.jp> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-3.0 (sh.osrg.net [192.16.179.4]); Tue, 13 Jul 2010 14:59:10 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1484 Lines: 27 On Mon, 12 Jul 2010 22:46:59 -0700 Zach Pfeffer wrote: > Joerg Roedel wrote: > > On Fri, Jul 02, 2010 at 12:33:51AM -0700, Zach Pfeffer wrote: > >> Daniel Walker wrote: > > > >>> So if we include this code which "map implementations" could you > >>> collapse into this implementations ? Generally , what currently existing > >>> code can VCMM help to eliminate? > >> In theory, it can eliminate all code the interoperates between IOMMU, > >> CPU and non-IOMMU based devices and all the mapping code, alignment, > >> mapping attribute and special block size support that's been > >> implemented. > > > > Thats a very abstract statement. Can you point to particular code files > > and give a rough sketch how it could be improved using VCMM? > > I can. Not to single out a particular subsystem, but the video4linux > code contains interoperation code to abstract the difference between > sg buffers, vmalloc buffers and physically contiguous buffers. The > VCMM is an attempt to provide a framework where these and all the > other buffer types can be unified. Why video4linux can't use the DMA API? Doing DMA with vmalloc'ed buffers is a thing that we should avoid (there are some exceptions like xfs though). -- 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/