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Date: Sat, 25 Oct 1997 21:55:35 +0000
From: =?iso-8859-1?Q?=DEor=F0ur?= Ivarsson <totii@est.is>
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To: Chuck Robey <chuckr@glue.umd.edu>
CC: "Jamil J. Weatherbee" <jamil@trojanhorse.ml.org>,
        freebsd-hackers@FreeBSD.ORG
Subject: Re: Parity Ram
References: <Pine.BSF.3.96.971025151431.21591L-100000@picnic.mat.net>
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Chuck Robey wrote:
> 
> On Sat, 25 Oct 1997, Žoršur Ivarsson wrote:
> 
> > Jamil J. Weatherbee wrote:
> > >
> > > Can someone fill me in on when you would want to use parity ram as opposed
> > > to non-parity ram these days?  If there was some anomaly in memory how
> > > would freebsd handle it (is there a trap for parity error?)
> >
> > As far as I know, the 'parity check fail' is connected to NMI of CPU.
> > In most cases the BIOS rutines accept this and halt the computer with no
> > information on where or why , only something like 'NMI detected, system
> > halted' or
> > 'Memory parity fail - NMI generated , system halted'.
> 
> Huh ?  BIOS routines?  What's that got to do with FreeBSD?  We don't use
> the BIOS routines, they don't get called at all, right?  If there's a
> parity violation, if that's wired to NMI, then the NMI get's called, but
> what that does is determined by FreeBSD, not your BIOS.
> 
> >
> > The only reason for this might be giving you some warning of failed
> > memory rather
> > than failed software.
> >
> > This has helped me several times when I was suspecting broken memory in
> > the old days (90-93) :-)
> >
> > Thordur Ivarsson

Ok, most of the old software and OSes did not fiddle with the NMI entry
point
so you did always get to the BIOS, but I don't know what happen in
FreeBSD it self.

Thordur Ivarsson