Feeping Creaturism (was Re: Unlimited software warranties)

[Ed Hall]

In article <428 at frcs.UUCP> paul at frcs.UUCP (Paul Nash) writes:
>The best bet is probably to go back to Version 7, which didn't have
>all the feeping creaturitis, and start again.  Oh, maybe tidy up
>the kernel, convert it to message-passing, so that device drivers
>are easier.
> . . . .
> it is available right
>now ... pay Prentice Hall $150 and get a copy of Minix.

I'm not going to let this slight on UNIX Version 7 go uncountered.

1) I've read both the V7 kernel and MINIX, and I have to admit, I
   found V7 easier to follow.  This isn't a fair test, since I worked
   with V7 first, but one might assume this would have helped with
   understanding MINIX.  Both are tidy, if K&R Standard C can be
   called "tidy".  Once I understood the idiom, V7 didn't *need*
   comments.
2) The message-passing nature of MINIX is the source of one of its
   worse bottlenecks--its kernel is single-threaded.  Nowhere does
   this impact performance so much as in the filesystem.  This could
   be fixed by adding message queues, and a lot of complexity.  Andy
   T. says "never".
3) I've written device drivers for V7 and for MINIX.  Once the whole
   wakeup/sleep mechanism is understood, V7 is as simple to write
   device drivers for as MINIX, and in some ways, easier.  For
   instance, the various message formats allowed in MINIX can be
   restrictive or confusing.  Messages must be passed in MINIX
   (say, between the FS and KERNEL) where V7 only needs to massage
   the appropriate data structure (perhaps between spl's).

That said, I like MINIX, and think it is an excellent teaching vehicle
and a source of great pleasure to folks who always wanted to hack
OS's.  Even in 1979 when it was released, UNIX V7 source was priced
about the same as System V is now (after inflation) for non-
Universities, keeping it out of the hands of hobbyists, while the
restrictions placed on University licensing prevented it from being a
teaching vehicle, at least for the scrupulous...

However, I agree with the original sentiment concerning System V,
and would apply it equally to BSD.  Perhaps the MACH folks have the
True Vision, even if they have yet to fulfill it.

		-Ed Hall
		edhall at rand.org