On Thu, 29 Oct 2020 21:04:30 -0700 John Stultz wrote: > > But I'll try to share my thoughts: > > So the system heap allows for allocation of non-contiguous buffers > (currently allocated from page_alloc), which we keep track using > sglists. > Since the resulting dmabufs are shared between multiple devices, we > want to provide a *specific type of memory* (in this case > non-contiguous system memory), rather than what the underlying > dma_alloc_attr() allocates for a specific device. If the memory slice(just a page for simple case) from dma_alloc_attr(for device-A) does not work for device-B, nor can page_alloc do the job imho. > > My sense is dma_mmap_wc() likely ought to be paired with switching to > using dma_alloc_wc() as well, which calls down to dma_alloc_attr(). > Maybe one could use dma_alloc_attr against the heap device to allocate > chunks that we track in the sglist. But I'm not sure how that saves us > much other than possibly swapping dma_mmap_wc() for remap_pfn_range()? _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
