On Fri, Sep 19, 2025 at 10:34:39 -0500, Andrea Bolognani wrote:
> On Fri, Sep 19, 2025 at 11:39:05AM +0200, Peter Krempa wrote:
> > On Tue, Aug 19, 2025 at 18:22:34 +0200, Andrea Bolognani via Devel wrote:
> > > +++ b/tests/qemuxmlconfdata/armv7l-versatilepb-minimal.armv7l-latest.args
> > > @@ -26,7 +26,7 @@
> > > XDG_CONFIG_HOME=/var/lib/libvirt/qemu/domain--1-armv7ltest/.config \
> > > -rtc base=utc \
> > > -no-shutdown \
> > > -boot strict=on \
> > > --device '{"driver":"pci-ohci","id":"usb","bus":"pci","addr":"0x1"}' \
> > > +-device '{"driver":"qemu-xhci","id":"usb","bus":"pci","addr":"0x1"}' \
> >
> > This change seems to have happened also in code paths not allowing ABI
> > update at least according to the filename.
>
> It only affects domains for which a model was not picked in the past.
> So effectively only new domains, regardless of the flags. Existing
> domains will keep using whatever model they're configured to use.
Beware that we historically considered also virDomainCreateXML
(transient wit possibly not fully filled XML) to be compatible across
runs. I know that we already didn't obey this in some cases but we
should consider this every time.
Especially in case of these limited boards the hardware you'd normally
built in will certainly not be XHCI
> > > +++ b/tests/qemuxmlconfdata/ppc-mac99-minimal.ppc-latest.abi-update.xml
> > > @@ -14,7 +14,7 @@
> > > <on_crash>destroy</on_crash>
> > > <devices>
> > > <emulator>/usr/bin/qemu-system-ppc</emulator>
> > > - <controller type='usb' index='0' model='piix3-uhci'>
> > > + <controller type='usb' index='0' model='pci-ohci'>
> >
> > I think I need to think about this a bit more. I agree that the
> > controller we picked didn't make sense for this machine, but in cases
> > when it did work (e.g. when you run linux with the proper driver) you
> > get something which doesn't resemble real hardware but likely works
> > better than 'pci-ohci'.
> >
> > So I'm not sure about the downgrade in this case, although we're
> > unlikely to break anything that'd be used widely in this case, breaking
> > it would go against our philosophy
>
> Is pci-ohci really a downgrade compared to piix3-uhci? They're both
> USB1 controllers. They should both have wide driver support and
> provide basic USB functionality. One just looks silly for non-x86
> machines.
Uh, yeah. I somehow thought this was 'ehci'/usb2.
> Plus as mentioned above existing guests will retain the existing
> model, so no actual breakage will happen.
See above.
