So what role does the memory management unit actually play in NetBSD?  Is it
the part that keeps nonprivileged processes from being able to look at
memory outside their personal space?  Does NetBSD use paging?  If it doesn't
use paging, it seems like it would be possible to make a kernel that wasn't
"safe" but would run.  (Processes could accidentally write into the memory
of other processes and a normal user would be able to write a program to
look at other people's memory.)   Amiga's operating system worked this way,
and although it wasn't the most stable thing in the world, it got along well
as a single-user machine.