Maybe some design concepts, but there was *no* code in
common. 
That is all I (or rather, the book) is claiming. I am not implying that
they ever shared code.
  No, the AIX kernel was *not* easily ported to other
architectures.
 That's why OSF chose Mach for the OSF/1 kernel.  I've been through the
 AIX kernel source (used to work in Austin) and I can tell you it is
 *very* specific to the POWER architecture.  The VM (which permeates the
 entire kernel -- address space is free) is welded to the POWER's MMU
 design. 
Well, I will have to go and find the book (which could take a long time),
but I am pretty sure it was a major design goal for that version (AIX 3, I
think?), and as I stated, was ported to other architectures that are
not very POWER. If the book is misleading - well, then I have been
misled. However, it is an official IBM document.
William Donzelli
aw288(a)osfn.org