Message-ID: <4C3BFDD3.8040209@codeaurora.org>
Date: Mon, 12 Jul 2010 22:46:59 -0700
From: Zach Pfeffer <zpfeffer@codeaurora.org>
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To: Joerg Roedel <joro@8bytes.org>
CC: Daniel Walker <dwalker@codeaurora.org>, Andi Kleen <andi@firstfloor.org>,
        Randy Dunlap <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
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> <1278021944.7738.43.camel@c-dwalke-linux.qualcomm.com> <4C2D965F.5000206@codeaurora.org> <20100710145639.GC10080@8bytes.org>
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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.

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