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From: mason@Pescadero.ARPA (Tony Mason)
Newsgroups: comp.arch,comp.unix.wizards,comp.os.misc
Subject: Re: Mach, the new standard?
Message-ID: <797@Pescadero.ARPA>
Date: Fri, 7-Aug-87 18:10:48 EDT
Article-I.D.: Pescader.797
Posted: Fri Aug  7 18:10:48 1987
Date-Received: Sun, 9-Aug-87 06:36:58 EDT
References: <1665@ncr-sd.SanDiego.NCR.COM> <8381@utzoo.UUCP>
Reply-To: mason@Pescadero.UUCP (Tony Mason)
Organization: Stanford University
Lines: 45
Keywords: Mach
Xref: mnetor comp.arch:1774 comp.unix.wizards:3607 comp.os.misc:82

I've spent much of the last five weeks working with Mach here, both reading
the internals stuff, and trying to get it running.  Internally and
design-wise, MACH is clean, efficient and quite elegant.  It was specifically
designed to work with networks, either as true networks of workstations 
(microVAX or Sun, etc.) or as "networks" of processors (multi-processor
machines.)

As for installing it, that has been a painful experience.  First, we just
installed a new VAX 8350 (2 cpu's.)  We have Ultrix 2.0 running on it (now)
but plan to migrate to MACH at some point, as Ultrix has problems of it's
own.  The 8350 is a BI based machine, and we have no attached UNIBUS.  Because
DEC has refused to let loose of a technical manual on the BI ethernet board
(and/or the Ultrix 2.0 driver source) CMU has been unable to write a driver
for it.  Thus, we could run MACH, but not talk to anyone.  That pretty well
defeats our purpose, so right now we are struggling with DEC to get a manual
to the BI board.

So, next I moved onto a microVAX.  Not your typical microVAX.  It has two
ra81's and a tk50.  None of those little drives here!  Ah, but alas, Stanford
is a big place, and there has been a lot of hacking on the source code to
4.3.  So what we have is not Vanilla 4.3.  I can boot the MACH kernel to
single user mode, but ls core dumps (illegal system calls - all that NFS code
installed in there.)  Once I recompiled ls with a non-NFS libc.a, I found out
our disk structure had been tampered with.  MACH trashes the super-block (not
MACH's fault - this is just because of local mods.)  After tracking down the
*original* 4.3 code from Berkeley, I am now in the process of rebuilding
EVERYTHING - 4.3, MACH and my disks. 

To sum up, MACH looks like a very promising operating system.  It maintains
full 4.3 compatibility but extends the original UNIX simplicity into this far
more complex jungle of machines we have today.  However, if you don't have a
vanilla 4.3 system running on the machine you want to install it on AND you
don't have a configuration supported by CMU, expect to put in some serious
sweat.  

Note that this isn't all CMU's fault.  In fact, none of it is really.  They
have been helpful every time we've dealt with them.  The problem lies with
uncooperative hardware companies and local "improvements."  

I hope this helps someone out there.

Tony Mason
Distributed Systems Group
Stanford University
mason@pescadero.stanfannalina