Re: [PATCH v8 02/18] hw/usb/hcd-xhci: Add an auto-hub property and leave it off

["Daniel P. Berrangé" <berrange@redhat.com>]

On Fri, Nov 06, 2026 at 03:45:58AM +0000, Jamin Lin wrote:
> > Subject: RE: [PATCH v8 02/18] hw/usb/hcd-xhci: Add an auto-hub property and
> > leave it off
> > 
> > > Subject: Re: [PATCH v8 02/18] hw/usb/hcd-xhci: Add an auto-hub
> > > property and leave it off
> > >
> > > Hi Jamin,
> > >
> > > On Mon, Nov 02, 2026 at 09:22:05AM +0000, Jamin Lin wrote:
> > > > Add auto-hub and leave it off. hw_compat_11_1 turns it on, so an
> > > > older machine type keeps the hub it has today and a guest saved by
> > > > an older QEMU still loads.
> > >
> > > Reran the migration check from v7: with pc-q35-11.1, a guest saved
> > > without the series loads on v8 with the hub in place, for qemu-xhci
> > > with four HID devices and for q35 -usb with six.
> > >
> > > But this missed the 11.2 soft freeze, so in 12.0 pc-q35-11.2 is an old
> > > machine type too, and hw_compat_11_1 (my suggestion on v7) doesn't
> > > cover it. Saved with pc-q35-11.2 on master, both cases fail on v8:
> > >
> > >   Unknown section or instance '0000:00:01.0/4/usb-hub' 0
> > >   Unknown section or instance '0000:00:1d.7/6/usb-hub' 0
> > >
> > > The entries from 02-05 want hw_compat_11_2 once the 12.0 machine types
> > > are in.
> > >
> > > Junjie
> > 
> > Hi Junjie, Marc-André, and Gerd,
> > 
> > Due to the QEMU code freeze and the planned 11.2 release in December,
> 
> 
> I am not sure about the correct release version. I expect it to be v11.2.
> If the version is wrong, please correct me.

Yes, the forthcoming release is 11.2, the version then ticks over to 12.0
for the first release of 2027.

> > disabling automatic hub creation while keeping migration compatibility with
> > older QEMU versions requires adding the property to hw_compat_11_2.
> > We need to wait until after the QEMU 11.2 release for the maintainers to add
> > hw_compat_11_2 to each machine type.
> > 
> > The USB redirection server is my original upstream goal, and I think this task is
> > independent of the automatic hub task.
> > So, I want to split the auto-hub changes into a separate prerequisite patch
> > series and send v9 after the QEMU 11.2 release.
> > 
> > The USB redirection server common protocol series still needs rework on the
> > device announcement and control transfer patches.
> > I will send v9 next week and mention that it requires the patch series that
> > disables automatic hub creation.
> > 
> > This way, we can continue testing and reviewing the USB redirection server
> > common protocol this month.(November)
> > 
> > "If you agree, I will send v9 next week. Otherwise, I will wait until after the
> > QEMU 11.2 release and then resend the full patch series as v9."

Don't delay sending new versions of your series because of the release
freeze.

Just put a "TODO: change to hw_compat_11_2 before merge" in the commit
message to call out the bit that you know needs changing before this
can be finally ready to merge.

With regards,
Daniel
-- 
|: https://berrange.com       ~~        https://hachyderm.io/@berrange :|
|: https://libvirt.org          ~~          https://entangle-photo.org :|
|: https://pixelfed.art/berrange   ~~    https://fstop138.berrange.com :|