On Thu, 2004-04-01 at 08:25, William Donzelli wrote:
Umm, no. AIX
has nothing in common with OS/400.
My source is "Introduction to the RS/6000", and official IBM document from
the very beginning of the line. If you give me some time, I could find the
book and give the IBM number. It is a thick engineering/sales freebie, and
has quite a few details of the internals of POWER and AIX (although not
enough to do anything fun). It states that a some of the aspects of AIX
were taken from OS/400 (I think aspects of the file system, but don't
quote me on that until I find the book).
Maybe some design concepts, but there was *no* code in common.
It is true that the AIX kernel (on POWER &
PPC) was a custom written
control program (written at T.J. Watson Research Center) with UNIX
semanitics layered on top. This was to take full advantage of the
POWER's architecture (especially in the VM area) that would have been
too much work to adapt a "standard" unix kernel to.
Well, sort of. AIX has a custom kernel, but was designed to be easily
ported to other architectures - namely Intel architectures. This is also
mentioned in the above document. This actually happened with the T386 and
T960 router cards, used with the old NSFnet RS/6000-T3Bs. Each router card
runs a cut down AIX on 80386 or 80960 microprocessors, and hadles all of
the routing duties - the RS/6000 is just there for the ride,
basically. These routing cards today are rarer than hen's teeth (look for
extra thick MCA cards (T960), or even extra tall ones (T386)).
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
TTFN - Guy