XROS had a completely new and rapidly evolving system call surface. No vendor would've been able to even start working on a driver for their device, let alone h

XROS had a completely new and rapidly evolving system call surface. No vendor would've been able to even start working on a driver for their device, let alone hand off a stable, complete result. It wasn't a case of "just rename a few symbols in a FreeBSD implementation and run a bunch of tests".