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 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.

It is only downstream decision to try to force it to use q35, despite it not working right today.