Re: [Linaro-mm-sig] [PATCH 08/10] mm: cma: Contiguous Memory Allocator added

From: Arnd Bergmann
Date: Wed Jun 15 2011 - 07:21:04 EST


On Wednesday 15 June 2011, Michal Nazarewicz wrote:
> On Tue, 14 Jun 2011 22:42:24 +0200, Arnd Bergmann <arnd@xxxxxxxx> wrote:
> > * We still need to solve the same problem in case of IOMMU mappings
> > at some point, even if today's hardware doesn't have this combination.
> > It would be good to use the same solution for both.
>
> I don't think I follow. What does IOMMU has to do with CMA?

The point is that on the higher level device drivers, we want to
hide the presence of CMA and/or IOMMU behind the dma mapping API,
but the device drivers do need to know about the bank properties.

If we want to solve the problem of allocating per-bank memory inside
of CMA, we also need to solve it inside of the IOMMU code, using
the same device driver interface.

Arnd
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