kern/59211: vio9p(4): missing from various GENERICs and MAKEDEVs

[campbell+netbsd%mumble.net@localhost]

>Number:         59211
>Category:       kern
>Synopsis:       vio9p(4): missing from various GENERICs and MAKEDEVs
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Mar 25 02:35:00 +0000 2025
>Originator:     Taylor R Campbell
>Release:        current
>Organization:
The Net9P Configuration
>Environment:
>Description:
The vio9p(4) device is handy in a VM guest for sharing file systems with a VM host such as qemu.

However, it is missing from various GENERIC kernels and MAKEDEV scripts.

It should be added to all the relevant kernel configurations and MAKEDEV scripts.
>How-To-Repeat:
try to use qemu 9p virtfs with a GENERIC guest
>Fix:
Yes, please!

While here, perhaps we should have a virtio.config file that can be included, like usbdevices.config, so we don't have to copy & paste the same block of virtio attachments in every kernel config.