On Fri, 2018-08-17 at 11:43 +0100, Daniel P. Berrangé wrote:
On Fri, Aug 17, 2018 at 12:35:11PM +0200, Andrea Bolognani wrote:
If we decide we want to explicitly spell out the options instead of relying on QEMU changing behavior based on the slot type, which is probably a good idea anyway, I think we should have
virtio-0.9 => disable-legacy=no,disable-modern=no virtio-1.0 => disable-legacy=yes,disable-modern=no
There's basically no reason to have a device legacy-only rather than transitional, and spelling out both options instead of only one of them just seems more robust.
From a testing POV it is desirable to be able to have legacy-only. There is also possibility that guest OS impl 1.0 in a buggy manner, so forcing legacy only is desirable.
The existing device still already provides a transitional option on i440fx, and on Q35 if you do explicit placement in a PCI slot. So I don't think there's a good reason to have a second transitional device type, especially if we're naming it virtio-0.9, it is rather misleading if it would be in fact able to run virtio-1.0 mode.
Sounds reasonable. -- Andrea Bolognani / Red Hat / Virtualization