Comment 13 for bug 1278977

We don't implement the sparc64 iommu, and the kernel expects to be able to use it.

The kernel sets up an iommu translation table, but qemu does not adjust its internal mappings,
and thus the first time the kernel touches the PCI bus we get an oops.

If you build a kernel with virtio built in, you can use a virtio disk, as that does not require the iommu.