Date: Wed, 14 Jul 2010 23:05:36 +0100
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Zach Pfeffer <zpfeffer@codeaurora.org>
Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>, ebiederm@xmission.com,
        linux-arch@vger.kernel.org, dwalker@codeaurora.org, mel@csn.ul.ie,
        linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, andi@firstfloor.org, linux-omap@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC 1/3 v3] mm: iommu: An API to unify IOMMU, CPU and device
	memory management
Message-ID: <20100714220536.GE18138@n2100.arm.linux.org.uk>
References: <4C3C0032.5020702@codeaurora.org> <20100713150311B.fujita.tomonori@lab.ntt.co.jp> <20100713121420.GB4263@codeaurora.org> <20100714104353B.fujita.tomonori@lab.ntt.co.jp> <20100714201149.GA14008@codeaurora.org>
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On Wed, Jul 14, 2010 at 01:11:49PM -0700, Zach Pfeffer wrote:
> If the DMA-API contained functions to allocate virtual space separate
> from physical space and reworked how chained buffers functioned it
> would probably work - but then things start to look like the VCM API
> which does graph based map management.

Every additional virtual mapping of a physical buffer results in
additional cache aliases on aliasing caches, and more workload for
developers to sort out the cache aliasing issues.

What does VCM to do mitigate that?
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