Re: [PATCH v2 0/2] qdev-monitor: avoid QemuOpts in QMP device_add

[Paul Durrant]

On 12/08/2024 19:15, Stefan Hajnoczi wrote:
> On Fri, Aug 02, 2024 at 10:10:43AM +0200, Markus Armbruster wrote:
> > Can we additionally cut out the QemuOpts middleman in
> > usbback_portid_add()?
> >
> >      qdict = qdict_new();
> >      qdict_put_str(qdict, "driver", "usb-host");
> >      tmp = g_strdup_printf("%s.0", usbif->xendev.qdev.id);
> >      qdict_put_str(qdict, "bus", tmp);
> >      g_free(tmp);
> >      tmp = g_strdup_printf("%s-%u", usbif->xendev.qdev.id, port);
> >      qdict_put_str(qdict, "id", tmp);
> >      g_free(tmp);
> >      qdict_put_int(qdict, "port", port);
> >      qdict_put_int(qdict, "hostbus", atoi(busid));
> >      qdict_put_str(qdict, "hostport", portname);
> >      opts = qemu_opts_from_qdict(qemu_find_opts("device"), qdict,
> >                                  &error_abort);
> >      usbif->ports[port - 1].dev = USB_DEVICE(qdev_device_add(opts, &local_err));
> >
> > Trying this is up to you!
>
> Paul or Anthony: Do you know how to run usbback_portid_add() for
> testing? I would like to make sure that suggested the code change works
> and don't have experience running the Xen code in QEMU.

Sorry, PV USB is not something I'm familiar with. 
https://wiki.xenproject.org/wiki/Xen_USB_Passthrough suggests that `xl 
usbdev-attach` might be the way to test... but you'd need a system with 
Xen installed and suitably configured guest, so not trivial to set up.