Maybe that's not such a good question (since I don't rightly know what a true mu-kernel is -- but I'm curious...) How about: do all the servers run only as user-mode processes? If so, would someone mind summing up what the whole mechanism/policy concept means with regard to the OBOS/BeOS client-server-kernel architecture? (After reading Daniel's newsletter article and Tanenbaum's Modern OS's chp.1, my interest is piqued. :)