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SubjectRe: How to efficiently handle DMA and cache on ARMv7 ? (was "Is get_user_pages() enough to prevent pages from being swapped out ?")
David Xiao wrote:
> Another approach is working from a different direction: the kernel
> allocates the non-cached buffer and then mmap() into user space. I have
> done that in similar situation to try to achieve "zero-copy".

open(O_DIRECT) does DMA to arbitrary pages allocated by userspace, and
O_DIRECT is used by some important applications, so the problem still
needs to be solved in general.

-- Jamie

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