Re: Power Mac Port and Mach 3.0 kernel

[turnbull@example.com (Stephen J. Turnbull)]

>>>>> "Craig" == Craig Oda <CRAIG@example.com> writes:

    Craig> Don't forget that the new Mac OS, Copeland, uses the same
    Craig> Mach 3.0 microkernel as Linux...  Wait a minute was that
    Craig> Mach 3.0 or was it just a microkernel....  hmm, can't
    Craig> remember what I read.

I'm fairly sure that Linux does not use the Mach microkernel, and I'm
also fairly sure that Linux cannot use the Mach microkernel because
although the Mach kernel is freely distributable for research
purposes, it is encumbered with a no-commercial-use license.  You can
use Mach in a commercial product, but only after jumping through the
legal hoops with Carnegie-Mellon U.  (If Mach were GPL, Stallman would 
have given up on the HURD a long time ago.  Maybe ;-)  Linux is
definitely GPL, so it is incompatible with incorporating any software
with a no-commercial-use license.

As far as I know Linux was not a micro-kernel; that's the point of
"modules," to make it closer to a micro-kernel.  But a micro-kernel,
strictly speaking, is the minimum amount of functions necessary to
support a protected multi-tasking OS.  That is a task-switcher, a
memory manager, and an I/O manager.  The drivers themselves live in
user space (I think).  AFAIK, Mach doesn't even support processes (I
think!).  Instead, there is a "kernel" that lives in user space (!) 
and manages processes for you.  These are called "single servers" in
microkernel jargon.  I believe that if you wish, you can run a Linux
SS, a BSD SS, a System V SS, a DOS SS, a Windows SS, a VMS SS, a MacOS
SS, and so on all at the same time and in this way not care whether
you are running Linux or what!!!!!!  Just teach each program where its
system calls live.  (I don't know how the hell you bootstrap the SS in 
this environment!!  Sheesh, talk about minimalism!)

Shinjirarenai-mon da ne.

I forget where to get info about Mach, but I've got some around
somewhere....  One of these days I'll go look it up on Alta Vista.

-- 
                            Stephen J. Turnbull
Institute of Policy and Planning Sciences                    Yaseppochi-Gumi
University of Tsukuba                      http://turnbull.sk.tsukuba.ac.jp/
Tennodai 1-1-1, Tsukuba, 305 JAPAN                 turnbull@example.com