Re: Signficant bugfix to my emulator

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

> Just ftr:  My invocation is like this:

[...]
>                 -deqna 0disable

Aha.  If I try it with no DEQNA, I find that the NetBSD ISO panics for
me too (I guess with XQA0 present, it doesn't get far enough to).

I did the full-tracing thing again: set output breaks on "mscpbus1:"
and "panic:", then, when the first one tripped, turn on full tracing
and slow down clock ticks by a factor of 100.  Turns out it's doing an
LDPCTX when not on the interrupt stack.  This is either a bug in the
kernel or fallout from something else wrong with the emulator.  Given
the recent successes on real hardware, I'm more inclined to suspect the
latter.

In the trace from the crash, the offending instruction is

(217086589 001f0000) 8000079a: 06                        ldpctx  

I've put the trace, from "mscpbus1:" to "panic:", up on
ftp.rodents-montreal.org, in
/mouse/misc/vax/2024-01-01.15:26:33.nb-iso-no-deqna, in case anyone
wants to have a look.  (It's a much bigger file than the other files I
put up for fetch - this one is 26163980 bytes.)  There are two ldpctx
instructions executed in the trace; the second one is the problematic
one.  I recommend searching for "ldpctx".

I don't know that kernel well enough to do much more with this myself.

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