Re: [Qemu-devel] [PATCH v2 0/7] APIC/IOAPIC cleanup

[Anthony Liguori]

On 08/23/2010 10:14 AM, Avi Kivity wrote:
>  On 08/23/2010 05:47 PM, Anthony Liguori wrote:
> > > > Devices can contain references to structs and objects.  If a Device 
> > > > contains a reference to an object, the object should be stored in a 
> > > > BusState which is a container of Devices.  Therefore, the object 
> > > > should inherit from Device.
> > >
> > > I disagree.  It's up to the author to decide whether to split a 
> > > Device into 1 or 15 objects.
> > >
> > > If one of the other objects is also a subclass of DeviceState, then 
> > > you're probably violating that DeviceState's contract.  But that's a 
> > > different (and trivial) matter.
> > >
> > > (side point: in C no objects have constructors and methods.  in C++ 
> > > all objects have constructors and methods, even PODs)
> >
> > Things that inherit from DeviceState have ctors/dtors.  Things that 
> > don't end up inventing their own and probably will do so poorly.
>
> you mean misimplement other_state_init(OtherState *) and 
> other_state_destroy(OtherState *)?

And hot plug, save/restore, properties, and all of the other things that 
go along with qdev.

Hot plug is a good example of how easy it is to screw this up by not 
having the right hooks being propagated through the device model.

Regards,

Anthony Liguori