(Thanks to Andrea Bolognani for bringing this to my attention) from https://libvirt.org/news.html: * v3.0.0 (unreleased) - qemu: Use virtio-pci by default for aarch64 mach-virt guests - virtio-pci provides several advantages over virtio-mmio, such as the ability to hotplug devices and improved performance. While opting in to virtio-pci has been possible for a while, newly-defined guests will now use it automatically. This is a good change because virtio-mmio is really slow, and because all other platforms (except S/390!) use virtio-pci and we want to minimize differences. I previously wrote a patch to make this happen in libguestfs: https://www.redhat.com/archives/libguestfs/2016-October/thread.html#00078 However the change was still being finalized in qemu & libvirt at that time, so I think that patch is probably not quite right for the final qemu/libvirt. In any case nothing is upstream. This is just a note that things will probably be broken for LIBGUESTFS_BACKEND=libvirt + libvirt 3.0.0 + aarch64 until we fix this in libguestfs. There is also a related RHEL bug: https://bugzilla.redhat.com/show_bug.cgi?id=1237250 Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-builder quickly builds VMs from scratch http://libguestfs.org/virt-builder.1.html