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If some ARM configs only give >>> order 4 folios or whatever then dmabuf heap doesn't care. >> >> The fundamental problem is that DMA allocations are highly >> architecture and device specific while Linux memory allocation APIs >> are generic. > > This isn't a dma allocation, this is a memory allocation. No, I mean this is a DMA-buf heaps allocation. It is a DMA allocation, we just don't know for which device. So ideally we should use resources which work for most devices in the system. If a device has special allocation requirements (CMA, restricted addressing etc...) we need a specialized DMA-buf heaps for it. That userspace provides this cc_shared flag is a NO-GO to begin with. Regards, Christian. > We made things so the CC shared folios are DMA mappable through the > DMA API. From the heap perspective the only difference is passing an > additional DMA_ATTR_CC_SHARED when DMA mapping the folio. > > Jason