Re: [Qemu-devel] [PATCH] ppc/xics: fix XICSStateClass parent class

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Feb 14, 2017 at 07:25:07AM +0100, Cédric Le Goater wrote:
> On 02/14/2017 02:58 AM, David Gibson wrote:
> > On Mon, Feb 13, 2017 at 10:33:24AM +0100, Cédric Le Goater wrote:
> >> XICSState inherits from SysBusDevice and so the object class should
> >> inherit from SysBusDeviceClass.
> >>
> >> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> > 
> > That's definitely a bug, but I don't think this is the right fix.
> > 
> > XICS was put on sysbus back when I thought that was where you put any
> > "system" devices that didn't belong on a more specific bus.  I've
> > since discovered that's not the case, and - particularly since xics
> > doesn't expose any mmio - it shouldn't be a sysbus device at all.
> > 
> > I've instead made a patch changing it to a direct child of
> > TYPE_DEVICE.  Since the device shouldn't ever be command line
> > instantiated, and it has no migratable state I believe this should be
> > a safe change.
> > 
> > This is in ppc-for-2.9, tentatively; please review:
> > 
> > From eae21fcf2430588f17e6a58d505aa8eaa580b507 Mon Sep 17 00:00:00 2001
> > From: David Gibson <david@gibson.dropbear.id.au>
> > Date: Tue, 14 Feb 2017 12:58:05 +1100
> > Subject: [PATCH] xics: XICS should not be a SysBusDevice
> > 
> > Currently xics - the component of the IBM POWER interrupt controller
> > representing the overall interrupt fabric / architecture is represented as
> > a descedent of SysBusDevice.  However, this is not really correct - the
> 
> descendant ?

descendent, actually, we were both wrong.

> 
> > xics presents nothing in MMIO space so it should be an "unattached" device
> > in the current QOM model.
> > 
> > Since this device will always be created by the machine type, not created
> > specifically from the command line, and because it has no migrated state
> > it should be safe to move it around the device composition tree.
> > 
> > Therefore this patch changes it to a descendent of TYPE_DEVICE, and makes
> > it an unattached device.
> > 
> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> 
> Reviewed-by: Cédric Le Goater <clg@kaod.org>
> 
> Thanks,
> 
> C.
> 
> > ---
> >  hw/intc/xics.c | 2 +-
> >  hw/ppc/spapr.c | 2 +-
> >  2 files changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/hw/intc/xics.c b/hw/intc/xics.c
> > index 095c16a..372b831 100644
> > --- a/hw/intc/xics.c
> > +++ b/hw/intc/xics.c
> > @@ -260,7 +260,7 @@ static void xics_common_class_init(ObjectClass *oc, void *data)
> >  
> >  static const TypeInfo xics_common_info = {
> >      .name          = TYPE_XICS_COMMON,
> > -    .parent        = TYPE_SYS_BUS_DEVICE,
> > +    .parent        = TYPE_DEVICE,
> >      .instance_size = sizeof(XICSState),
> >      .class_size    = sizeof(XICSStateClass),
> >      .instance_init = xics_common_initfn,
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index 6f37288..9b6ad0f 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -101,7 +101,7 @@ static XICSState *try_create_xics(const char *type, int nr_servers,
> >      Error *err = NULL;
> >      DeviceState *dev;
> >  
> > -    dev = qdev_create(NULL, type);
> > +    dev = DEVICE(object_new(type));
> >      qdev_prop_set_uint32(dev, "nr_servers", nr_servers);
> >      qdev_prop_set_uint32(dev, "nr_irqs", nr_irqs);
> >      object_property_set_bool(OBJECT(dev), true, "realized", &err);
> > 
> 

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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