On Mon, Aug 25, 2014 at 10:18:46AM -0700, Andy Lutomirski wrote: > Currently, a lot of the virtio code assumes that bus (i.e. hypervisor) > addresses are the same as physical address. This is false on Xen, so > virtio is completely broken. I wouldn't be surprised if it also > becomes a problem the first time that someone sticks a physical > "virtio" device on a 32-bit bus on an ARM SOC with more than 4G RAM. > > Would you accept patches to convert virtio_ring and virtio_pci to use > the DMA APIs? I think that the only real catch will be that > virtio_ring's approach to freeing indirect blocks is currently > incompatible with the DMA API -- it assumes that knowing the bus > address is enough to call kfree, and I don't think that the DMA API > provides a reverse mapping like that. If you use the dma_map/unmap_sg all of that ends up being stuck in the sg structure (sg->dma_address ends with the DMA addr, sg_phys(sg) gives you the physical address). > > --Andy > > -- > Andy Lutomirski > AMA Capital Management, LLC _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
