On Fri, Sep 23, 2016 at 12:03:26PM +0200, Paolo Bonzini wrote: > > > On 23/09/2016 12:02, Peter Xu wrote: > > On Fri, Sep 23, 2016 at 11:27:09AM +0200, Paolo Bonzini wrote: > >> > Since the whole IOMMU feature is new and somewhat experimental, I think > >> > it's okay to just make EIM the default for >=2.8 machine types if KVM is > >> > on (using DEFINE_PROP_ON_OFF_AUTO; auto means true if KVM is on and > >> > false otherwise, and pc-2.7 would set eim=off). It means requiring > >> > kernel 4.8 by default, but I don't think it's a big deal. > > I think the problem is, even we have KVM support for x2apic, we are > > still losing QEMU part. And guests with cluster x2apic and >8 vcpus > > will not working properly on device interrupts, which can be very > > confusing to people (it can boot, but some devices just don't work > > properly, and they won't see useful information in guest dmesg). > > Yes, that's why I suggested EIM=on by default.
I am confused. :( Why not we just keep people from that wrong configuration by default, until we have x2apic in QEMU? -- peterx
