On Mon, Feb 15, 2016 at 09:41:57AM +0000, Peter Maydell wrote: > On 15 February 2016 at 09:35, Martin Kletzander <mkletzan@xxxxxxxxxx> 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.) I know Pavel Fedin was trying to revive kernel_irqchip=off once, but I don't know if that effort was abandoned or not. I think it could be a nice-to-have, in order to help isolate bugs with KVM, but I agree running that way wouldn't be the norm. Thanks, drew -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list