Re: [libvirt] [Qemu-devel] clean/simple Q35 support in libvirt+QEMU for guest OSes that don't support virtio-1.0

On Fri, Aug 17, 2018 at 03:13:22PM +0200, Markus Armbruster wrote: > Daniel P. Berrangé <berrange(a)redhat.com&gt; writes: > > > On Fri, Aug 17, 2018 at 12:35:11PM +0200, Andrea Bolognani wrote: > >> On Fri, 2018-08-17 at 10:29 +0100, Daniel P. Berrangé wrote: > >> > On Thu, Aug 16, 2018 at 06:20:29PM -0400, Laine Stump wrote: > >> > > 5) Some guest OSes that we still want to support (and which would > >> > > otherwise work okay on a Q35 virtual machine) have virtio drivers too > >> > > old to support virtio-1.0 (CentOS6 and RHEL6 are examples of such OSes), > >> > > but due to the chain of reasons listed above, the "standard" config for > >> > > a Q35 guest generated by libvirt doesn't support virtio-0.9, hence > >> > > doesn't support these guest OSes. > >> > > >> > Note when talking about "support" you're really saying it from the > >> > downstream vendor, specifically RHEL, POV. From upstream or Fedora POV > >> > essentially all x86 OS ever made are in scope for running under QEMU > >> > if suitable virtual hardware models have been provided. QEMU doesn't > >> > maintain any whitelist of "supported" OS that differs from what is > >> > technically capable of being run, in the way downstream vendors do. > >> > >> Well, at least in the case of RHEL 6, "not supported" means that it > >> will not boot at all on q35 with the default guest topology created > >> by libvirt, so that's not really a downstream-only problem :) > > > > I mean from an upstream POV we still support RHEL-6 fine in i440fx, > > so there's no reason to particularly care about RHEL-6 with q35 > > upstream. > > Only true if Q35 provides nothing of value over i440FX for RHEL-6 > guests. Does it? Q35 has little technical benefit over i440fx for the majority of guest deployments, regardless of guest OS.