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Date: Fri, 12 Apr 2013 11:33:15 +0200
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Subject: Re: [Qemu-devel] [PATCH] virtio-balloon: fix dynamic properties.
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: aliguori@us.ibm.com, mark.burton@greensocs.com, qemu-devel@nongnu.org, Luiz Capitulino <lcapitulino@redhat.com>, cornelia.huck@de.ibm.com, afaerber@suse.de

On 12/04/2013 11:14, Peter Maydell wrote:
> On 12 April 2013 09:36, KONRAD Fr=C3=A9d=C3=A9ric <fred.konrad@greensoc=
s.com> wrote:
>> On 12/04/2013 10:29, Peter Maydell wrote:
>>> Does the approach I suggested on IRC where virtio-balloon-pci's
>>> property set/get callbacks just set/get the property on
>>> virtio-balloon via the public interface not work? Having to
>>> expose virtio-balloon's callback functions seems a bit of
>>> an encapsulation violation...
>> Oh, I didn't understand that like that.
>>
>> What do you mean by the public interface?
> I mean the interface that any user of an object should
> use to access properties, ie object_property_set()
> and object_property_get(). Something like:
>
> static void balloon_pci_fwd_get(Object *obj,
>       struct Visitor *v, void *opaque, const char *name, Error **errp)
> {
>      VirtIOBalloonPCI *dev =3D VIRTIO_BALLOON_PCI(obj);
>      object_property_get(OBJECT(&dev->vdev), v, name, errp);
> }
>
> Ditto for fwd_set; note that you can use the same accessors
> for any property you need to forward to the underlying
> virtio-balloon-device. Untested :-)
>
> -- PMM
Note, I'm having a kind of similar issue with virtio-rng:

virtio-rng-pci have actually a child device named "default-backend".

The logic wants that default-backend is a child of virtio-rng-device but=20
as we
want to keep compatibility.

And it's not possible to have this default-backend be a child of=20
virtio-rng-pci and virtio-rng-device at the same time.