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From: Wilko Bulte <wilko@yedi.iaf.nl>
Message-Id: <199504062017.WAA00849@yedi.iaf.nl>
Subject: on parity error reporting..
To: FreeBSD-hackers@FreeBSD.org (FreeBSD hackers list)
Date: Thu, 6 Apr 1995 22:17:46 +1596657 (MET DST)
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Hi

Currently (== 1.1.5 & 2.0R) the kernel handles NMI parity interrupts by
displaying an error and panicing. I assume -current does something
similar.

What about the following:

	isa_nmi:	

		check_if_actually_parity_int
		if not, report and panic 
		mask NMI for a while
		clear parity hardware
		install special NMI catcher
		enable NMI
		loop thru physmem from 0 to top of memory, scanning
			memory, hoping error re-occurs
		if it does, have catcher return *approximate* address
			of error
		if not, display message telling user
		finally PANIC!

There are caveats (e.g. caches?!) but would the above be something that works?
I know ATT V.3 did do address reporting. Lacking decent hardware (address
register containing the error address, like a decent PDP-11 ;-) I see no
other way to do it.

Reason for asking: I have a mainboard giving me *1* error, on boot. After
that, it runs solid for days. 

I'd be happy to try an approach like outlined above, but it probably needs
assembly code support etc. Intel assembly is something I'm not familiar with
(and actually, would rather not _become_ familiar with ;-). 

Comments and suggestions are welcome

Wilko
_     __________________________________________________________________________
 |   / o / /  _   Wilko Bulte             email: wilko@yedi.iaf.nl
 |/|/ / / /( (_)  Private FreeBSD site  - Arnhem - The Netherlands
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