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From: ghelmer@dsuvax.uucp (Guy Helmer)
Newsgroups: comp.os.minix
Subject: MINIX 1.5.10 ignores NMI on Intel machines?
Keywords: NMI
Message-ID: <1990Aug16.021356.24004@dsuvax.uucp>
Date: 16 Aug 90 02:13:56 GMT
Organization: Dakota State University
Lines: 33

I've recently discovered that my main MINIX machine is suffering memory
lossage.  I suspected it for some time, but didn't have proof since
I saw no panics while MINIX was running and never received the dreaded
PARITY ERROR while running MS-DOS junk.  Finally, MINIX became extremely
unstable, so I dusted off the diagnostic software for this machine and
located the faulty bank of RAM.

My beef is: I though MINIX would have panic'ed as fast as possible on
receipt of NMI, which at least on XT-class machines means parity trouble.
There is no way an operating system should continue if this condition
occurs.

Assuming MINIX doesn't reset the D-type flip-flop at i/o addr 0xa0
to stop NMI's from reaching the processor, I've been researching the
kernel sources to find out what happens when an NMI occurs.  So far,
I think I see code in mpx.x accepting the nmi and calling exception
in exception.c; exception is supposed to either call cause_sig() in
system.c or panic.  I lose track of SIGBUS at that point, and it doesn't
seem to matter anyway since I haven't found any code to deal with
a SIGBUS (and signal.h indicates that SIGBUS is "obsolete", which
I have trouble believing right now).

Can the kernel gurus please help?  I'll keep searching and try to
find a place to stick a handler, but I think this kind of problem
should panic ASAP to lessen the chance of multiple NMI's and peripheral
corruption.

Thanks in advance.
-- 
Guy Helmer
work: DSU Computing Services, Business & Education Institute    (605) 256-5315
play: MidIX System Support Services                             (605) 256-2788
dsuvax!ghelmer@cs.utexas.edu, ...!bigtex!loft386!dsuvax!ghelmer