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SubjectRe: [PATCH 1/5] dma: create dma_generic_alloc/free_coherent()
On Tue, 2009-10-27 at 09:57 +0900, Paul Mundt wrote:
> On Mon, Oct 26, 2009 at 05:24:58PM -0600, Alex Williamson wrote:
> > Move dma_generic_alloc_coherent() out of x86 code and create
> > corresponding dma_generic_free_coherent() for symmetry. These
> > can then be used by IOMMU drivers attempting to implement
> > passthrough mode.
> >
> Except that dma_generic_alloc_coherent() is only "generic" for platforms
> with consistent DMA. Everyone else will need a cacheflush and potentially
> a remap. It's not even obvious from looking at the consistent DMA
> platforms that they'll be able to use it out of the box due to expecting
> something other than page_address(), which all suggests that this is
> better off remaining an x86-only routine.
> This is also making changes to the DMA-API without any documentation
> updates and without consulting with any other architecture people.

Ok, thanks for the feedback. Let's forget this patch and I'll see how
amenable David is to doing something within intel-iommu since it only
supports platforms with consistent DMA. Thanks,


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