On Mon, Jun 24, 2013 at 11:01:54AM -0300, Eduardo Habkost wrote:
> On Sat, Jun 22, 2013 at 04:50:33PM +0800, Hu Tao wrote:
> > Cc: qemu-devel@nongnu.org
> > Cc: "Andreas Färber" <afaer...@suse.de>
> > Cc: Paolo Bonzini <pbonz...@redhat.com>
> > Cc: Anthony Liguori <aligu...@us.ibm.com>
> > Cc: Igor Mammedov <imamm...@redhat.com>
> > Cc: Eduardo Habkost <ehabk...@redhat.com>
> > Signed-off-by: Hu Tao <hu...@cn.fujitsu.com>
> > ---
> > hw/i386/kvm/clock.c | 8 +++-----
> > 1 file changed, 3 insertions(+), 5 deletions(-)
> >
> > diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c
> > index 87d4d0f..74aa240 100644
> > --- a/hw/i386/kvm/clock.c
> > +++ b/hw/i386/kvm/clock.c
> > @@ -87,12 +87,11 @@ static void kvmclock_vm_state_change(void *opaque, int
> > running,
> > }
> > }
> >
> > -static int kvmclock_init(SysBusDevice *dev)
> > +static void kvmclock_realize(DeviceState *dev, Error **errp)
> > {
> > - KVMClockState *s = FROM_SYSBUS(KVMClockState, dev);
> > + KVMClockState *s = DO_UPCAST(KVMClockState, busdev.qdev, dev);
> >
> > qemu_add_vm_change_state_handler(kvmclock_vm_state_change, s);
> > - return 0;
> > }
> >
> > static const VMStateDescription kvmclock_vmsd = {
> > @@ -111,9 +110,8 @@ static const VMStateDescription kvmclock_vmsd = {
> > static void kvmclock_class_init(ObjectClass *klass, void *data)
> > {
> > DeviceClass *dc = DEVICE_CLASS(klass);
> > - SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass);
> >
> > - k->init = kvmclock_init;
> > + dc->realize = kvmclock_realize;
>
> Is TYPE_SYS_BUS_DEVICE guaranteed to never override ->realize() itself?
>
> From DeviceClass documentation:
>
> * If a type derived directly from TYPE_DEVICE implements @realize, it does
> * not need to implement @init and therefore does not need to store and call
> * #DeviceClass' default @realize callback.
> * For other types consult the documentation and implementation of the
> * respective parent types.
>
> The problem is that there's no documentation about ->realize() on
> SysBusDeviceClass. Can we please explicitly document SysBusDeviceClass
> expectations about ->realize() first, before making those changes?
IIUC, subclass's overriding ->realize should call parent's ->realize at
some point. Peter Crosthwaite has a patchset to access a object's parent
class at http://lists.nongnu.org/archive/html/qemu-devel/2013-06/msg02982.html
Regarding SysBusDevice::init and SysBusDevice::realize, I think it's the
same as in the case of DeviceClass. If you agree I'll document it as in
DeviceClass.
