On 12 December 2012 17:53, Andreas Färber <afaer...@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
