I was thinking that's hard, but I noticed that vpp get ported to FreeBSD using epoll shim library, and I learnt apple Darwin use some some userland of FreeBSD to do POSIX compatibility, then after some tests and hacking, most related to minor POSIX API adaptation such as mmap and one major coroutine need add some assembly code, and it work! But I think most disappointed to me is that apple do lack some vectorized network IO unless do some kernel extension or other sort non standard ways.