On Mon, Oct 15, 2018 at 06:27:21AM -0400, Michael S. Tsirkin wrote:
> On Mon, Oct 15, 2018 at 10:16:41AM +0200, Gerd Hoffmann wrote:
> > On Fri, Oct 12, 2018 at 11:54:35PM -0300, Eduardo Habkost wrote:
> > > The current virtio-*-pci device types actually represent 3
> > > different types of devices:
> > > * virtio 1.0 non-transitional devices
> > > * virtio 1.0 transitional devices
> >
> > Ok.
> >
> > > * virtio 0.9 ("legacy device" in virtio 1.0 terminology)
> >
> > Why? Is there any reason to prefer 0.9 over transitional?
I don't know. The `disable-modern` option already exists but I
don't know who would want to use it. I'm just adding a way to
represent that existing feature without having another set of
device types with multiple-personality disorder.
> >
> > cheers,
> > Gerd
>
> Right - maybe a flag to disable modern interface is enough.
> We thus get two types:
> - transitional (legacy)
> - non-transitional (modern)
> which matches spec nicely.
I would agree with the removal of virtio-*-0.9 only if we decide
to drop support for disable-modern=true. If we still want to
provide a legacy-only virtio device, it should be a separate
device type.
Without separate device types, it becomes impossible to provide
meaningful device type information to management software,
including but not limited to:
* removal/deprecation of device types (especially important if we
plan to remove virtio 0.9 support from QEMU one day)
* PCI IDs
* Bus compatibility information
* Schema/introspection for 0.9-only or 1.0-only device options
--
Eduardo
