On Mon, 19 Sep 2016 22:07:13 +0300 "Michael S. Tsirkin" <mst@xxxxxxxxxx> wrote: > On Wed, Sep 07, 2016 at 09:38:04PM +0200, Sascha Silbe wrote: > > Dear Laine, > > > > Laine Stump <laine@xxxxxxxxx> writes: > > > > > On 09/07/2016 02:35 PM, Sascha Silbe wrote: > > >> "Daniel P. Berrange" <berrange@xxxxxxxxxx> writes: > > >> [...] > > >>> <sound model="virtio"/> == QEMU virtio > > >>> <sound model="virtio1.0"/> == QEMU virtio + disable-legacy > > >> What would this do for devices using the virtio-ccw transport? > > > > > > From libvirt's point of view, the option "disable-legacy=on" would be > > > added to the device's commandline argument. > > > > Which would break s390x guests. virtio-ccw doesn't have any concept of > > "legacy" or "modern" devices (that's purely a virtio-pci concept), > > Legacy is a generic concept found in virtio 1 spec. > Modern isn't, virtio 1 only has transitional/non-transitional. > > If you want to stick to the spec you should therefore > use > legacy/transitional/non-transitional > at the API level. > > It is true that not all transports have all options. > ccw does not support non-transitional devices, > mmio does not support transitional ones. We basically have: - legacy devices: pci, ccw - standard-compliant devices: pci, ccw, mmio - of these, pci and ccw have transitional support, which can be disabled for pci Per default, I don't think libvirt should offer legacy devices - I see this as a machine-version backwards-compatibility option which should be handled via the machine version only. It makes sense to have a way to force pci devices to either transitional or non-transitional. For ccw and mmio, this is not applicable. Therefore, I think libvirt should offer a switch to handle transitional/non-transitional pci only and not provide any other virtio-version switches. -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list