Re: [SeaBIOS] [Qemu-devel] [PATCH v2 3/4] i386: generate pc guest info

[Michael S. Tsirkin]

On Wed, Jul 24, 2013 at 04:52:05PM +0200, Andreas Färber wrote:
> Hi Gerd,
>
> Am 24.07.2013 16:42, schrieb Gerd Hoffmann:
> > > > This does not satisfy the "should use QOM properties" requirement that
> > > > we discussed in the RFC thread.
> > >
> > > I don't know which part of the RFC thread still applied and
> > > which doesn't: at that point you were rejecting the whole
> > > approach.
> > >
> > > I found a mail where you said:
> > >    I'd be a lot happier if we were passing more information to this routine
> > >    and not hard coding it.  For instance, the PCI interrupt assignments,
> > >    the APIC ids, the number of available CPUs, etc.
> > >
> > > So this is exactly what this code does.
> > > What, exactly, would you like to see instead?
> > > Create a guest info QOM object, and encode all information used by ACPI
> > > generation as properties of this object?
> >
> > Don't touch device code for this.
> > > > > -void pvpanic_init(ISABus *bus)
> > > > > +void pvpanic_init(ISABus *bus, PcGuestInfo *guest_info)
> > > > >  {
> > > > >      ISADevice *dev;
> > > > > FWCfgState *fw_cfg = fw_cfg_find();
> > > > > FWCfgState *fw_cfg = guest_info->fw_cfg;
> > > > > if (!fw_cfg) {
> > > > >     return;
> > > > > }
> > > > > dev = isa_create_simple (bus, TYPE_ISA_PVPANIC_DEVICE);
> > > > > pvpanic_fw_cfg(dev, fw_cfg);
> > > > > pvpanic_guest_info(dev, guest_info);
> > > > >
> > > > > }
> >
> > To pick this one as example:  Instead of patching pvpanic code to stuff
> > config info into GuestInfo you should (1) search the device object tree
> > for a pvpanic device and (b) if present read the ioport property to
> > figure the base address.
>
> Yeah, the above does not feel so nice from a QOM view (didn't review the
> ACPI series yet).

If you do please review v3 which was just posted.
It should address your comment - though long term,
it would be nicer if we had multiple inheritance
for interfaces, then we could expose a generic
panic interface with the io port number,
avoid need to poke at specific device.
> > /me suggests to check out qmp_qom_get() in qmp.c.  Some qom aequivalent
> > for qdev_find_recursive would be handy, dunno whenever such a thing
> > exists already, Andreas?
>
> Not sure what's needed here? object_resolve_path() and
> object_foreach_child() come to mind...
>
> Regards,
> Andreas
> > I'd tend to accept GuestInfo as temporary thing for stuff which can't be
> > figured using qom properties today.  Anthony might disagree though.
> >
> > cheers,
> >   Gerd