On 2020/12/8 下午3:02, Enrico Weigelt, metux IT consult wrote:

On 08.12.20 03:36, Jason Wang wrote:

Hi,

quoted

So we endup with two solutions (without a prompt):

1) using select, user may end up with driver without transport

IMHO not an entirely unusual situation in other places of the kernel,
eg. one can enable USB devices, w/o having an usb host adapter enabled.

And even if some USB-HA driver is enabled, the actualy machine doesn't
necessarily have the corresponding device.

Ok, then select works for me.

quoted

2) using depends, user need to enable at least one transport

2) looks a little bit better I admit.

So, all virtio devices should depend on TRANSPORT_A || TRANSPORT_B ||
TRANSPORT_C || ... ? (and also change all these places if another
transport is added) ?

I think not. The idea is, if none of the transport (select VIRTIO) is 
enabled, user can not enable any virtio drivers (depends on VIRTIO).

Thanks

--mtx