Re: How to efficiently handle DMA and cache on ARMv7 ? (was "Is get_user_pages() enough to prevent pages from being swapped out ?")

[Laurent Pinchart]

On Friday 07 August 2009 00:25:43 Russell King - ARM Linux wrote:
>
> As far as userspace DMA coherency, the only way you could do it with
> current kernel APIs is by using get_user_pages(), creating a scatterlist
> from those, and then passing it to dma_map_sg().  While the device has
> ownership of the SG, userspace must _not_ touch the buffer until after
> DMA has completed.

If the buffers are going to be reused again and again, would it be possible to 
mark the pages returned by get_user_pages() as non-cacheable instead ?

Regards,

Laurent Pinchart

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