[libvirt] [PATCH v2 2/2] Allow PCI virtio on ARM "virt" machine

[Gerd Hoffmann]

On Mi, 2015-07-01 at 19:32 -0400, Cole Robinson wrote:
> On 06/30/2015 02:47 AM, Pavel Fedin wrote:
> >  Hello!
> > 
> >> Unfortunately thinking about this some more, the current patch approach might
> >> not be acceptable as is, since current distros as a guest don't support -M
> >> virt with PCI... for example Fedora 21 or 22.
> > 
> >  How can this be?
> >  If qemu version is new enough, virt machine should have a PCI controller. You do not have to supply
> > any extra options, it's just there. It's in mainstream. Or do your distros artificially raise
> > version number?
> >  Or are you talking about distros themselves? But... Again, how? Do you have "Generic PCI
> > controller" and virtio-PCI drivers disabled in .config of your kernel? Why? Shouldn't this be fixed
> > then?
> >  virtio-PCI has much better performance than virtio-mmio, because you can use vhost-net with irqfds
> > on it.
> 
> I'm talking about the distro kernel as a guest. My understanding is that
> Fedora 21/22 AArch64 does _not_ work with virtio-pci, but it does work with
> virtio-mmio. But I've yet to confirm yet...

arm64 has no generic pci host support yet (as of upstream kernel 4.1).
arm has it for a while (and at least f22 works just fine with it).

cheers,
  Gerd