UUCP Port Turnaround (==> Unix Kernel hacks)

[terryl at tekcrl.UUCP]

In article <395 at stracs.cs.strath.ac.uk> jim at cs.strath.ac.uk writes:
+In article <3233 at rsch.WISC.EDU> mcvoy at rsch.WISC.EDU (Lawrence W. McVoy) writes:
+>.. the people at CMU have something called MACH ....  It's a message
+>passing kernel based on Accent that is binarily compatible with 4.3BSD on 
+>Vax, source compatible elsewhere.  It's supposedly well designed,
+>easy to maintain, and has some new features that make Unix look sick (like
+>copy-on-write MM, used to get pass-by-value saftey with pass-by-reference
+>speed, msg based so networking is cake, user loadable drivers, pagers, etc).
+
+Granted MACH has lots of interesting things in it, but it is HUGE. Even
+a BSD kernel pales into insignificance. I recall someone from CMU saying
+that their development kernel had a 700K text segment! OK - it may have
+had lots of redundant code for development work, but I can't see how MACH
+could be smaller than a comparable Berkeley kernel with all these nice new
+ideas that CMU are implementing. 


     I was going to stay out of this, but here are some sizes on /vmunix from
various machines I use:
text	data	bss	dec	hex
192040	88216	98800	379056	5c8b0	/vmunix, VAX 11/780 running 4.3
text	data	bss	dec	hex
311108	44472	140656	496236	7926c	/vmunix, same VAX running mach
text	data	bss	dec	hex
253056	24436	69342	346834	54ad2	/vmunix, 68010 workstation with 4.2
text	data	bss	dec	hex
246944	30532	39356	316832	4d5a0	/vmunix, 68020 workstation with 4.2

     NOTE: these sizes do NOT include all of the data structures allocated
dynamically, i.e. disk buffers, in-core inodes, file structs, etc. Also,
the workstations are running significantly different flavors of 4.2, with
the 68010 workstation more vanilla 4.2. Both workstations also have some
sort of remote file system, whereas the VAX does not. Last note: the 68020
workstation kernel was compiled using the Greenhills compiler, whereas the
68010 was compiled with the MIT. I would guestimate that the 68010 kernel
would probably shrink by 10-15% by using the Greenhills compiler.

+The MACH kernel source might be prettier, but can we afford the extra core
+needed to run it? :-)


     Uh, I hate to burst your bubble, but the MACH sources are definitely
NOT prettier. They have made some strides, but unfortunately, there are
still a lot of VAX'isms sprinkled throughout the code. Also, MACH hasn't
quite split things up into machine-independent and machine-dependent sources,
most specifically in the VM subsystem. These observations are from direct
experience.


			Terry Laskodi
			     of
			Tektronix