Re: virtio-vsock requires 'disable-legacy=on' in QEMU 5.1

[Cornelia Huck]

On Tue, 18 Aug 2020 16:01:20 +0200
Stefano Garzarella <sgarzare@redhat.com> wrote:

> On Tue, Aug 18, 2020 at 02:44:50PM +0200, Cornelia Huck wrote:

> > It seems to me that the status before this was "works by accident, but
> > only if we're not negotiating to legacy, or the guest/host are both
> > little endian". IOW, no visible breakage for most people (or we'd
> > probably have heard of it already). Now we have a setup that's correct,
> > but forces users to adapt their QEMU command lines. Option 1 would
> > eliminate the need to do that, but would cause possibly
> > not-really-fixable migration issues (you can probably deal with that
> > manually, detaching and re-attaching the device as a last resort.)
> > 
> > So, force modern, probably also remove the -transitional device type,
> > and put a prominent explanation into the change log?
> >   
> 
> I completely agree with your analysis and solution.
> 
> So, for now we need to patch vhost-vsock-pci and vhost-user-vsock-pci,
> and queue the patches in stable.

I think we should also change -ccw; even though users won't get an
error when starting QEMU, they might still run into the legacy problems
in theory.

Not sure how fast we'll have a stable release, though.

> 
> Do you prefer to send them? Otherwise I can do that.

If you already have something on your disk, please go ahead :)

> 
> Thanks again for the help and the test with s390x guest!

np; especially as it was my patch which started this in the first place
:/