On 9/2/26 12:59, Leon Romanovsky wrote: ... >> The PCI_P2PDMA_MAP_BUS_ADDR is not supported by DMA-buf and as far as I can >> see is a complete dead end. > > Maybe you mean DRM, but VFIO works perfectly with PCI_P2PDMA_MAP_BUS_ADDR > flow in DMA-buf. > What am I missing?
Well not quite. The approach PCI_P2PDMA_MAP_BUS_ADDR takes is fundamentally tied to only map a physical CPU address into a PCI address and doesn't take into account that in a lot of configurations the CPU can't access all resources. So when VFIO uses PCI_P2PDMA_MAP_BUS_ADDR it only works for a small subset of the use cases DMA-buf supports, but yeah as always in DMA-buf pretty much everything is optional. Regards, Christian. > > Thanks
