Regarding #2 from comment #19:
As the defined range for the ipv6.mtu is from IPV6_MIN_MTU to the device's MTU, and the existing API returns an error if the ipv6.mtu is out of range, I think it's reasonable for a configuration with the ipv6.mtu > device MTU to fail.
Regarding #2 from comment #19:
As the defined range for the ipv6.mtu is from IPV6_MIN_MTU to the device's MTU, and the existing API returns an error if the ipv6.mtu is out of range, I think it's reasonable for a configuration with the ipv6.mtu > device MTU to fail.