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SubjectRe: [PATCH v6 4/5] dma-buf: heaps: Add CMA heap to dmabuf heaps
On Thu, Jul 25, 2019 at 03:20:11PM +0200, Benjamin Gaignard wrote:
> > But that just means we need a flag that memory needs to be contiguous,
> > which totally makes sense at the API level. But CMA is not the only
> > source of contigous memory, so we should not conflate the two.
>
> We have one file descriptor per heap to be able to add access control
> on each heap.
> That wasn't possible with ION because the heap was selected given the
> flags in ioctl
> structure and we can't do access control based on that. If we put flag
> to select the
> allocation mechanism (system, CMA, other) in ioctl we come back to ION status.
> For me one allocation mechanism = one heap.

Well, I agree with your split for different fundamentally different
allocators. But the point is that CMA (at least the system cma area)
fundamentally isn't a different allocator. The per-device CMA area
still are kinda the same, but you can just have one fd for each
per-device CMA area to make your life simple.

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