Re: [Qemu-devel] [PATCH 0/2] target-i386: "custom" CPU model + script to dump existing CPU models

[Peter Maydell]

On 24 June 2015 at 15:38, Paolo Bonzini <address@hidden> wrote:
> It's certainly okay for libvirt and OpenStack to use the host CPU
> features in order to check whether a node will run a given VM.  However,
> libvirt should trust that QEMU developers will not prevent a VM from
> running on a previously viable host, just because you change the machine
> type.

Note that this might be true for x86 but isn't (in full generality)
necessarily so for other architectures like ARM. For instance if
you have a host machine with a GICv3 with no v2-back-compatibility
support, then you can run a VM whose machine type specifies a GICv3,
but not machine types that require a GICv2...

thanks
-- PMM