Userland instability in NetBSD 6.0.1 MacPPC

[Donald Lee <MacPPC2%c.icompute.com@localhost>]

I have been debugging a problem with a logfile analyzer - analog
(http://analog.cx) which I have been using for years.  It's not
very stylish, but it does the job.

I have noticed in the last few weeks that the byte counts have gone nuts.
Instead of gigabytes, I have petabytes, and I don't know why.  I have
assumed that this is due to "corrupt" logfine entries, or some other data
input issue, like too much data.

Tonight, I've been running tests, splitting up the input files and trying
to figure out which part of the input causes the problem, with little
progress to report.

HOWEVER, I noticed that if I run the exact program with the same input
twice, I get different crazy numbers. (!!)

This may well be due to some bug in analog where it is referencing some
uninitialized data that just happens to be different on every run.

It occurs to me, though that if single threaded (and analog is old, so
I would expect that), even bugs should be deterministic.  I wonder if
the "different answers on different runs" might be caused by some OS
behavior where it is not properly zeroing new vm pages, or some other
anti-social, but not fatally incorrect behavior.

Just a thought for those who know NetBSD's internals better than I do.

I have seen some strange behavior that seems non-reproducable, though
it's hard to tell when bringing up a new box and debugging 12
things at once.

-dgl-