The XNU kernel is not a BSD kernel, it's a Mach kernel. There may be some BSD code in it (the unfinished net80211 wifi stack for iOS, ipfw/pf firewall, MAC fram

The XNU kernel is not a BSD kernel, it's a Mach kernel. There may be some BSD code in it (the unfinished net80211 wifi stack for iOS, ipfw/pf firewall, MAC framework, some things bolted on to make it traditional unix-y), but it's not a BSD kernel.