I'm not saying there's anything missing, just that there isn't much in it; it's a mirror of the already-existing "tethered RISC-V" proxy kernel, with a trivial hello-world app on top of it (the app listens for messages over the "HTIF" interface, uses NaCL to encrypt/decrypt them, and implements essentially "hello world").

Compare to the object/capability schemes in modern L4s.