Re: [Qemu-devel] [PATCH 06/18] qom: add child properties (composition)

[Anthony Liguori]

On 12/02/2011 05:54 AM, Kevin Wolf wrote:
> Am 30.11.2011 22:03, schrieb Anthony Liguori:
> > Child properties express a relationship of composition.
> >
> > Signed-off-by: Anthony Liguori<address@hidden>
>
> Do we have a flag or something that makes sure that a child is never
> removed without its parent? The code assumes that child stays valid as
> long as the parent lives.

Good question.  This is an interesting issue with qdev.

The child property is not writable so you cannot detach a child.  That's because 
the child's life cycle is supposed to be tied to the parents.

qdev doesn't have the right bits to handle this right now.  I think that's 
fixable by just adding a new flag to DeviceState.

> > @@ -499,4 +499,24 @@ gchar *qdev_get_canonical_path(DeviceState *dev);
> >    */
> >   DeviceState *qdev_resolve_path(const char *path, bool *ambiguous);
> >
> > +/**
> > + * @qdev_property_add_child - Add a child property to a device
> > + *
> > + * Child properties form the composition tree.  All devices need to be a child
> > + * of another device.  Devices can only be a child of one device.
> > + *
> > + * There is no way for a child to determine what it's parent is.  It is not
>
> s/it's/its/

Ack.

Regards,

Anthony Liguori

> Kevin