[libvirt] [Qemu-devel] [RFC PATCH 0/2] ARM: add QMP command to query GIC version

[Peter Maydell]

On 15 February 2016 at 09:35, Martin Kletzander <mkletzan at redhat.com> wrote:
> So hardware itself supports some GIC version, let's say 3 for our case.
> Does that mean it can be triggered to do v2 as well?  I mean is it
> possible that HW supports multiple versions?  If yes, then I suspect
> there is (will be) HW that does *not* do it

Hardware may be:
 GICv2 only
 GICv3 only
 GICv3 with v2 backwards-compatibility support

> and that's where QEMU (or
> KVM) must emulate that version.

If the hardware doesn't support the version that we are trying
to provide to the guest then we can't run KVM at all. (KVM
with an emulated interrupt controller is not a supported setup,
because you wouldn't get CPU timer interrupts in the guest.)

thanks
-- PMM