Comment by invernomut0

Some years ago I was working on an embedded platform with two processors connected via ethernet, one handling data and most of the application load, the second one handling some automotive buses (CANbus and ARCnet). I wrote a kernel driver to expose raw data coming from the ARCnet to userspace applications in the most transparent way. So I labeled data coming from the second cpu with an unused ethertype, I changed the ethernet driver to inspect the ether type of the incoming data and send it up inside the network stack as if it was received from a certain fake ARCnet device. The fake ARCnet device was a dummy module that allowed userspace to receive that data via normal sockets. Probably it could be done in a better way but it was quite simple and it worked well.