Re: [RFC 1/3 v3] mm: iommu: An API to unify IOMMU, CPU and devicememory management

From: Russell King - ARM Linux
Date: Wed Jul 14 2010 - 18:07:11 EST


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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