Re: [Qemu-devel] [PATCH v5 00/16] uq/master: Introduce basic irqchip support

[Avi Kivity]

On 12/20/2011 12:03 PM, Avi Kivity wrote:
> On 12/20/2011 04:46 AM, Anthony Liguori wrote:
> >
> > I would hope that you would agree that when designing the device
> > model, we should aim to do what makes sense independent of migration. 
> > If we cannot achieve a certain feature with migration given the
> > logical modeling of devices, it probably suggests that we need to
> > improve our migration infrastructure.
> >
> > I assume that given the above, we all agree that separate devices is
> > what makes the most sense ignoring migration.
>
> I don't agree with this.

The problem with having two devices, is that now you have to identify
the common code, put them somewhere, and use them as necessary.

"apic" and "kvm-apic" both is-a (are-a?) "apic".  This suggests either a
base class (containing the common code) and derived classes, or (like
Jan's implementation), just one class, that defers part of the
implementation to an interface implemented by two other classes.

Two unrelated classes which happen to implement exactly the same
interface (vmstate fields) except one (visible name) and share some code
are a strange solution to this problem.

-- 
error compiling committee.c: too many arguments to function