On Wed, Dec 19, 2018 at 09:12:55PM +0100, Paolo Bonzini wrote: > On 19/12/18 09:50, Peter Xu wrote: > > Starting from QEMU 4.0, let's specify "split" as the default value for > > kernel-irqchip. > > > > So for QEMU>=4.0 we'll have: allowed=Y,required=N,split=Y > > for QEMU<=3.1 we'll have: allowed=Y,required=N,split=N > > (omitting all the "kernel_irqchip_" prefix) > > > > Note that this "split" is optional - we'll first try to enable split > > kernel irqchip, and we'll fall back to complete kernel irqchip if we > > found that the kernel capability is missing. > > Please just fail completely and require a new kernel for the 4.0 machine > type. There are subtle differences between kernel and QEMU irqchip, I > don't think we want to open that can of worms. This would make existing VMs that are runnable with pc-q35-3.1.0 not runnable by only updating the machine-type. The good news is that we can make this a non-issue by clearly documenting that QEMU needs a more recent kernel (just like we'll do for RDTSCP[1]). [1] https://lore.kernel.org/lkml/20181210181328.GA762@xxxxxxx/ -- Eduardo -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
