brk's zero-fill behavior on VAXen

[William Bolosky]

In the process of putting up the Mach VM implementation here at CMU we
introduced a bug which caused newly allocated memory to not be zeroed in
some esoteric circumstances.  This caused malloc to behave incorrectly
(malloc itself, not things using it), at very infrequent intervals.

It's hard to guess just what else relies on this, but I would wager that
there are more things that do...

BTW, On the IBM RT PC the 0 opcode is a jump instruction, and 0000 means
(guess what) "jump to yourself."  This is annoying.
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Bill Bolosky
Mach Kernel Group, Carnegie-Mellon University CSD
ARPA: bolosky at wb1.cs.cmu.edu
BITNET: wb0g at cmcctb.bitnet