Messages in this thread | | | Date | Thu, 25 Jul 2019 07:33:35 -0700 | From | Christoph Hellwig <> | Subject | Re: [PATCH v6 4/5] dma-buf: heaps: Add CMA heap to dmabuf heaps |
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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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