Hi everyone, We're currently developing a new communication using custom layer 2 and 3 that we'll be using in a cubesat and I'm looking on how to create the layer 3 driver for linux (similar to af_inet.c but the headers are completely different). I've read something similar in a thread about a previously asked question here, but it didn't really answer my questions. And so, my questions are: 1. Will it suffice to patch linux/socket.h and insert the PF_xxxx before PF_MAX then use the added PF_xxxx as family in struct net_proto_family? 2. Is there another way to do the above without patching and only in an out-of-tree module? 3. How do I expose the new AF_xxxx to userspace? It seems like macros for AF_xxxx are placed in bits/socket.h, but I haven't found a way to patch it. Thanks, Cedric