This is xnu-8019. See this file in:
Directory listing for xnu-8019//bsd/miscfs/devfs
Makefile
README
devfs.h
devfs_fdesc_support.c
devfs_proto.h
devfs_tree.c
devfs_vfsops.c
devfs_vnops.c
devfsdefs.h
fdesc.h
reproto.sh