Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754258Ab0GJOgi (ORCPT ); Sat, 10 Jul 2010 10:36:38 -0400 Received: from 8bytes.org ([88.198.83.132]:46486 "EHLO 8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752798Ab0GJOgg (ORCPT ); Sat, 10 Jul 2010 10:36:36 -0400 Date: Sat, 10 Jul 2010 16:36:35 +0200 From: Joerg Roedel To: Zach Pfeffer Cc: Hari Kanigeri , Daniel Walker , Andi Kleen , Randy Dunlap , 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 Message-ID: <20100710143635.GA10080@8bytes.org> References: <1277877350-2147-1-git-send-email-zpfeffer@codeaurora.org> <1277877350-2147-3-git-send-email-zpfeffer@codeaurora.org> <20100701101746.3810cc3b.randy.dunlap@oracle.com> <20100701180241.GA3594@basil.fritz.box> <4C2D908E.9030309@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4C2D908E.9030309@codeaurora.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1271 Lines: 28 On Fri, Jul 02, 2010 at 12:09:02AM -0700, Zach Pfeffer wrote: > Hari Kanigeri wrote: > >> He demonstrated the usage of his code in one of the emails he sent out > >> initially. Did you go over that, and what (or how many) step would you > >> use with the current code to do the same thing? > > > > -- So is this patch set adding layers and abstractions to help the User ? > > > > If the idea is to share some memory across multiple devices, I guess > > you can achieve the same by calling the map function provided by iommu > > module and sharing the mapped address to the 10's or 100's of devices > > to access the buffers. You would only need a dedicated virtual pool > > per IOMMU device to manage its virtual memory allocations. > > Yeah, you can do that. My idea is to get away from explicit addressing > and encapsulate the "device address to physical address" link into a > mapping. The DMA-API already does this with the help of IOMMUs if they are present. What is the benefit of your approach over that? Joerg -- 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/