Re: [PATCH 3/5] vDPA: introduce vDPA bus

[Jason Wang]

On 2020/1/17 äå10:12, Rob Miller wrote:
>     >> + * @get_vendor_id:Â Â Â Â Â Get id for the vendor that
>     provides this device
>     >> + *Â Â Â Â Â Â Â Â Â Â Â Â Â @vdev: vdpa device
>     >> + *Â Â Â Â Â Â Â Â Â Â Â Â Â Returns u32: virtio vendor id
>     > what's the idea behind this? userspace normally doesn't interact
>     with
>     > this ... debugging?
>
>
>     This allows some vendor specific driver on top of vDPA bus. If
>     this is
>     not interested, I can drop this.
>
> RJM>] wouldn't usage of get_device_id & get_vendor_id, beyond 
> reporting, tend to possibly leading to vendor specific code in the 
> framework instead of leaving the frameworkÂagnostic and leave the 
> vendor specific stuff to the vendor's vDPA device driver?


For virtio device id, I think it is needed for kernel/userspace to know 
which driver to load (e.g loading virtio-net for networking devic).

For virtio vendor id, it was needed by kernel virtio driver, and virtio 
bus can match driver based on virtio vendor id. So it doesn't prevent 
3rd vendor specific driver for virtio device.

Maybe we can report VIRTIO_DEV_ANY_ID as vendor id to forbid vendor 
specific stuffs.

Thanks