Re: [Qemu-devel] [PATCH 03/61] virtio-pci-bus : introduce virtio-pci-bus.

["KONRAD Frédéric" <fred.konrad@greensocs.com>]

On 09/01/2013 15:53, Peter Maydell wrote:
> On 9 January 2013 09:14, KONRAD Frédéric <fred.konrad@greensocs.com> wrote:
>> On 09/01/2013 09:37, KONRAD Frédéric wrote:
>>> On 08/01/2013 19:08, Peter Maydell wrote:
>>>> This isn't quite right, I think (somebody correct me if I'm wrong!)
>>>> The virtio-pci-bus subclass doesn't have any state of its own, so it
>>>> doesn't need a struct, but it does still want a type, so virtio-pci.h
>>>> should
>>>> have a
>>>>      typedef VirtioBusClass VirtioPCIBusClass;
>>>>      typedef VirtioBusState VirtioPCIBusState;
>>>> and we then use VirtioPCIBusClass/State where appropriate
>>>> (notably in the typeinfo for class/instance size and in the get-class/
>>>> class-check/etc macros).
>>>>
>>>> This lets us easily add state later if we need to by turning the
>>>> typedef into a typedef'd struct without having to hunt down all
>>>> the places that now need to say 'VirtioPCIBus*' rather than
>>>> 'VirtioBus*'.
>>> Ok, I'll make the change.
>> Though, I'm not really sure we will add something here..
>> The virtio-pci-bus is only added to implement VirtioBusClass functions.
>> There are no differences between pci, s390, or mmio.
> It's just consistency, and as I say it avoids surprises later. We're
> basically inventing our own object system in C here, which means
> that there's no guard preventing you from doing something in a
> way which is inconsistent with our object system but still valid
> and functioning C; but it's better style not to do that.
>
> -- PMM
ok then, I'll change it. And for s390 too.