From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-f176.google.com (mail-lb0-f176.google.com [209.85.217.176]) by kanga.kvack.org (Postfix) with ESMTP id 28EFD6B006E for ; Tue, 3 Feb 2015 11:37:23 -0500 (EST) Received: by mail-lb0-f176.google.com with SMTP id z12so39589188lbi.7 for ; Tue, 03 Feb 2015 08:37:22 -0800 (PST) Received: from mout.kundenserver.de (mout.kundenserver.de. [212.227.17.13]) by mx.google.com with ESMTPS id d7si4118477wie.43.2015.02.03.08.37.20 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 03 Feb 2015 08:37:21 -0800 (PST) From: Arnd Bergmann Subject: Re: [Linaro-mm-sig] [RFCv3 2/2] dma-buf: add helpers for sharing attacher constraints with dma-parms Date: Tue, 03 Feb 2015 17:36:59 +0100 Message-ID: <7233574.nKiRa7HnXU@wuerfel> In-Reply-To: References: <1422347154-15258-1-git-send-email-sumit.semwal@linaro.org> <6906596.JU5vQoa1jV@wuerfel> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: owner-linux-mm@kvack.org List-ID: To: linaro-kernel@lists.linaro.org Cc: Rob Clark , Russell King - ARM Linux , Tomasz Stanislawski , LKML , DRI mailing list , "linaro-mm-sig@lists.linaro.org" , "linux-mm@kvack.org" , Daniel Vetter , Robin Murphy , "linux-arm-kernel@lists.infradead.org" , "linux-media@vger.kernel.org" On Tuesday 03 February 2015 11:22:01 Rob Clark wrote: > On Tue, Feb 3, 2015 at 11:12 AM, Arnd Bergmann wrote: > > I agree for the case you are describing here. From what I understood > > from Rob was that he is looking at something more like: > > > > Fig 3 > > CPU--L1cache--L2cache--Memory--IOMMU-----device > > > > where the IOMMU controls one or more contexts per device, and is > > shared across GPU and non-GPU devices. Here, we need to use the > > dmap-mapping interface to set up the IO page table for any device > > that is unable to address all of system RAM, and we can use it > > for purposes like isolation of the devices. There are also cases > > where using the IOMMU is not optional. > > > Actually, just to clarify, the IOMMU instance is specific to the GPU.. > not shared with other devices. Otherwise managing multiple contexts > would go quite badly.. > > But other devices have their own instance of the same IOMMU.. so same > driver could be used. I think from the driver perspective, I'd view those two cases as identical. Not sure if Russell agrees with that. Arnd -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org