Re: sysbus failed assert for xen_sysdev

[Jason Andryuk]

On Tue, Jun 23, 2020 at 9:22 AM Paul Durrant <xadimgnik@gmail.com> wrote:
>
> > -----Original Message-----
> > From: Jason Andryuk <jandryuk@gmail.com>
> > Sent: 23 June 2020 13:57
> > To: Markus Armbruster <armbru@redhat.com>
> > Cc: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>; Anthony PERARD 
> > <anthony.perard@citrix.com>; xen-
> > devel <xen-devel@lists.xenproject.org>; Paul Durrant <paul@xen.org>; QEMU 
> > <qemu-devel@nongnu.org>
> > Subject: Re: sysbus failed assert for xen_sysdev

> >
> > Thanks for your response, Markus.
> >
> > I didn't write it, but my understanding is as follows.  TYPE_XENSYSDEV
> > is a device on the system bus that provides the TYPE_XENSYSBUS bus.
> > TYPE_XENBACKEND devices can then attach to TYPE_XENSYSBUS.
> >
> > That would make the qom-tree something like:
> >   /TYPE_XENSYSDEV
> >     /TYPE_XENSYSBUX
> >       /TYPE_XENBACKEND
> >
> > (I think today the TYPE_XENBACKEND devices ends up attached to the System 
> > bus.)
> >
> > I think TYPE_XENSYSDEV is correct - it is a device on the system bus.
> > static const TypeInfo xensysdev_info = {
> > .name = TYPE_XENSYSDEV,
> > .parent = TYPE_SYS_BUS_DEVICE,
> > ...
> > }
> >
> > TYPE_XENSYSBUS is the xen-specific bus - provided by TYPE_XENSYSDEV -
> > for attaching xendev.
> > static const TypeInfo xensysbus_info = {
> > .name = TYPE_XENSYSBUS,
> > .parent = TYPE_BUS,
> > ...
> > }
> >
> > TYPE_XENBACKEND is a generic Xen device and it plugs into
> > TYPE_XENSYSBUS.  Maybe the .parent here is wrong and it should just be
> > TYPE_DEVICE?
>
> Yes, I think that is the problem leading to the assert. See the equivalent 
> (non-legacy) code in xen-bus.c.

Yes, xen-bus.c looks correct, but the important change seems to be
removing `dc->bus_type = TYPE_XENSYSBUS;` from xen_sysdev_class_init()
and adding it to xendev_class_init().  That let QEMU get to the
cfi.pflash01 assertion failure.

Regards,
Jason

>   Paul
>
> > static const TypeInfo xendev_type_info = {
> > .name = TYPE_XENBACKEND,
> > .parent = TYPE_XENSYSDEV,
> > ...
> > }
> >
> > So removing `bus_type = TYPE_XENSYSBUS` from TYPE_XENSYSDEV class_init
> > and adding it to TYPE_XENBACKEND seems correct to me.