Re: [Qemu-devel] [RFC PATCH v7 7/8] virtio-pci-blk : Switch to new API.

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

On 12/12/2012 18:58, Peter Maydell wrote:
> On 12 December 2012 17:53, Andreas Färber <afaerber@suse.de> wrote:
>> Am 12.12.2012 15:25, schrieb Peter Maydell:
>>> How will the PCI transport's PCI vendor/device/class IDs be
>>> set (a) when a virtio-blk backend is created and separately
>>> plugged into a virtio-pci transport (b) for the legacy
>>> virtio-pci-blk? [ideally the answer to (b) should be "in the
>>> same way as for (a)"]
>> The obvious answer would be that PCI properties need to be set on the
>> PCI device, not an a VirtioDevice sitting on a virtio-bus.
>>
>> I.e., with the proposed refactoring we'd have on the virtio-bus:
>>
>> - VirtioDevice
>>    + VirtioBlockDevice
>>    + VirtioSCSIDevice - has-a scsi-bus
>>    ...
>>
>> In turn that means that every VirtioDevice to be exposed as PCI device
>> to the guest needs it own PCIDevice exposing a private virtio-bus.
>>
>> - PCIDevice
>>    - VirtioPCIDevice - has-a virtio-bus
>>      + virtio-blk-pci - has-a VirtioBlockDevice on its virtio-bus
>>      + virtio-scsi-pci - has-a VirtioSCSIDevice on its virtio-bus
>>      ...
> ...this bit is only for legacy back-compat. It should be equally
> valid to just use the PCI transport plugged into a VirtioDevice,
> both of which were created by the user with -device [and for
> new transports, separate transport and backend should be the
> standard]. That means the virtio-bus interface needs a way for
> the backend to announce to the transport what it is so that
> the PCI transport can set the right PCI IDs.
>
> -- PMM
Yes, it's done with uint16_t get_virtio_device_id(VirtioBusState *bus) 
function from second step.