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. Paolo
