Re: [Qemu-devel] [RFC PATCH v2 1/3] virtio-bus : Introduce VirtioBus.

[Konrad Frederic <fred.konrad@greensocs.com>]

On 26/11/2012 17:59, Anthony Liguori wrote:
> Peter Maydell<peter.maydell@linaro.org>  writes:
>
>> On 26 November 2012 14:33, Anthony Liguori<aliguori@us.ibm.com>  wrote:
>>> VirtioBusInfo is not a great name.  This is a proxy class that allows
>>> for a device to implement the virtio bus interface.
>>>
>>> This could be done as an interface but since nothing else uses
>>> interfaces, I'm okay with something like this.  But the first argument
>>> ought to be an opaque for all methods.
>> We have at least one user of Interface in the tree IIRC.
>> I'd much rather we did this the right way -- the only reason
>> it's the way Fred has coded it is that there's no obvious
>> body of code in the tree to copy, so we're thrashing around
>> a bit. If you tell us what the correct set of structs/classes/
>> interfaces/etc is then we can implement it :-)
> I really think extending virtio-bus to a virtio-pci-bus and then
> initializing it with a link to the PCI device is the best approach.
>
> It's by far the simpliest approach in terms of coding.
>
> Did I explain it adequately?  To recap:
>
> virtio-bus extends bus-state
>   - implements everything that VirtIOBindings implements as methods
>
> virtio-pci-bus extends virtio-bus
>   - is constructed with a pointer to a PCIDevice
>   - implements the methods necessary to be a virtio bus
I still have trouble with that ^^.

virtio-pci-bus extends virtio-bus so I put something like that :

static void virtio_pci_bus_class_init(ObjectClass *klass, void *data)
{
     BusClass *bc = BUS_CLASS(klass);
     VirtioBusClass *k = VIRTIO_BUS_CLASS(klass);
     /* VirtIOBindings */
     k->notify = virtio_pci_notify;
     k->save_config = virtio_pci_save_config;
     k->load_config = virtio_pci_load_config;
     k->save_queue = virtio_pci_save_queue;
     k->load_queue = virtio_pci_load_queue;
     k->get_features = virtio_pci_get_features;
     k->query_guest_notifiers = virtio_pci_query_guest_notifiers;
     k->set_host_notifier = virtio_pci_set_host_notifier;
     k->set_guest_notifiers = virtio_pci_set_guest_notifiers;
     k->vmstate_change = virtio_pci_vmstate_change;
     /*
      * TODO : Init and exit function.
      * void (*init)(void *opaque);
      * void (*exit)(void *opaque);
      */
}

static TypeInfo virtio_pci_bus_info = {
     .name          = TYPE_VIRTIO_PCI_BUS,
     .parent        = TYPE_VIRTIO_BUS,
     .class_init    = virtio_pci_bus_class_init,
};

and I have VirtioDevice which extends DeviceState like that :

static void virtio_device_class_init(ObjectClass *klass, void *data)
{
     /* Set the default value here. */
     DeviceClass *dc = DEVICE_CLASS(klass);
     dc->bus_type = TYPE_VIRTIO_BUS;
     dc->init = virtio_device_init;
}

static TypeInfo virtio_device_info = {
     .name = TYPE_VIRTIO_DEVICE,
     .parent = TYPE_DEVICE,
     .instance_size = sizeof(VirtioDeviceState),
     /* Abstract the virtio-device */
     .class_init = virtio_device_class_init,
     .abstract = true,
     .class_size = sizeof(VirtioDeviceClass),
};

The problem is that the virtio devices can't be connected to the 
virtio-pci-bus even if it extends virtio-bus because TYPE_VIRTIO_BUS != 
TYPE_VIRTIO_PCI_BUS.

Did I miss something ?

Thanks,

Fred


> virtio-device extends device-state
>   - implements methods used by virtio-bus
>
> Regards,
>
> Anthony Liguori
>
>> -- PMM