On Sun, Aug 05, 2018 at 03:09:55AM +0300, Michael S. Tsirkin wrote: > So in this case however I'm not sure what exactly do we want to add. It > seems that from point of view of the device, there is nothing special - > it just gets a PA and writes there. It also seems that guest does not > need to get any info from the device either. Instead guest itself needs > device to DMA into specific addresses, for its own reasons. > > It seems that the fact that within guest it's implemented using a bounce > buffer and that it's easiest to do by switching virtio to use the DMA API > isn't something virtio spec concerns itself with. And that is exactly what we added bus_dma_mask for - the case where the device itself has not limitation (or a bigger limitation), but the platform limits the accessible dma ranges. One typical case is a PCIe root port that is only connected to the CPU through an interconnect that is limited to 32 address bits for example. _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
