Вот, кстати, на досуге просматривал такой чудный документ как "L4 User Manual NICTA L4-embedded API" (
http://l4hq.org/docs/manuals/l4uman-n1.pdf) от университета Нового Уэльса в Австралии, где Игорь Кац на седьмой странице (она же первая страница первой главы) говорит следующее: "The basic idea of a μ-kernel goes back to Brinch Hansen’s Nucleus [BH70] and Hydra [WCC+74] and has been popularised by Mach [RTY+88]. The argument goes that by reducing the size of the kernel (the part of the OS executing in privileged mode) it becomes possible to build a system with a smaller trusted computing base, which results in a more secure and reliable system."