On Mon, Apr 29, 2019 at 09:22:12AM -0600, Alex Williamson wrote: [...] > > > What's a good 4.0.1 strategy to resolve this? Re-instate KVM irqchip > > > as the Q35 default? I can't see that simply switching to current QEMU > > > handling is a viable option for performance? What about 4.1? We could > > > certainly improve EOI support in QEMU, there's essentially no support > > > currently, but it seems like an uphill battle for an iothread based > > > userspace ioapic to ever compare to KVM handling? Thanks, > > > > irqchip=split and irqchip=kernel aren't guest ABI compatible, are > > they? That would make it impossible to fix this in pc-q35-4.0 > > for a 4.0.1 update. > > I suppose it would require a pc-q35-4.0.1 machine type :-\ Thanks,
I wonder if it's possible to untangle this and make the irqchip option stop affecting guest ABI on 4.1+ machine-types? This way QEMU could choose smarter defaults in the future without the compatibility code hassle. -- Eduardo
