Is your feature request related to a problem? Please describe.
When I run following command,

ip -6 route add ace:cab:deca:1f:1b::/80 encap ip6 dst ace:cab:deca:18::21 dev gnv0

I got this error:

Error: CONFIG_LWTUNNEL is not enabled in this kernel.

Describe the solution you'd like
Looks like lightweight tunnel is not enabled via CONFIG_LWTUNNEL. Is it possible to enable that?

Describe alternatives you've considered

Additional context
I'm trying to set up a many-to-many GENEVE overlay network among nodes. Since I don't want to create a tun device for every other nodes, I'd like to use lightweight tunnel feature so I can set tunnel metadata via routes and have only one tun device.

See

• https://lwn.net/Articles/650778/
• https://man7.org/linux/man-pages/man8/ip-route.8.html