On Thu, 2016-03-10 at 09:56 +0000, Daniel P. Berrange wrote:
So, I've just seen that QEMU has decided that as of QEMU 2.6, the
virt
machine type will start to be versioned. This is quite convenient I
think as it gives us a nice thing to hook on. ie we see a non-versioned
machine type of 'virt' then we use virtio-mmio addressing, however, if
we see a versioned virt-X.Y.Z machine type, then we can assume pci by
default.
Since the long term plan for AArch64 is to use PCI for everything, this
gives us nice default behaviour from this point onwards, while not
breaking compatibility for existing early adopters.
Of course people with "legacy" mmio-only guests will stll have a little
pain to run then on new QEMU, but honestly I think that's worth it since
it will avoid us long term pain in the world where aarch64 uses pci for
everything
I think it's way too early to flip the switch and default to
PCI addresses: my understanding is that guest OS support is
expected to be spotty at best for at least a couple more
years.
Cheers.
--
Andrea Bolognani
Software Engineer - Virtualization Team