Many people are surprised to learn that Linux (and I guess some of the BSDs?) have a virtual machine that runs in the kernel and executes its own specific bytecode. LLVM has a BPF backend, as mentioned in this article.
Prior to BPF there was "Enet Packet Filter", then Ultrix Packet Filter then something under SunOS before it became BPF. BPF was created in 1990 (at Berkeley) which was widely BSD oriented.
