From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jason Wang <jasowang@redhat.com>
Subject: Re: [PATCH 3/5] vDPA: introduce vDPA bus
Date: Mon, 20 Jan 2020 16:19:10 +0800
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On 2020/1/17 =E4=B8=8B=E5=8D=8810:12, Rob Miller wrote:
>
>
>     >> + * @get_vendor_id:=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 Get id for=
 the vendor that
>     provides this device
>     >> + *=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0=
 =C2=A0 =C2=A0 =C2=A0 =C2=A0 @vdev: vdpa device
>     >> + *=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0=
 =C2=A0 =C2=A0 =C2=A0 =C2=A0 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=C2=A0 usage of get_device_id & get_vendor_id, beyond=20
> reporting, tend to possibly leading to vendor specific code in the=20
> framework instead of leaving the framework=C2=A0agnostic and leave the=20
> vendor specific stuff to the vendor's vDPA device driver?


For virtio device id, I think it is needed for kernel/userspace to know=20
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=20
bus can match driver based on virtio vendor id. So it doesn't prevent=20
3rd vendor specific driver for virtio device.

Maybe we can report VIRTIO_DEV_ANY_ID as vendor id to forbid vendor=20
specific stuffs.

Thanks