Date: Mon, 24 Sep 2001 21:13:42 -0400 (EDT) From: Andrew Gallatin <gallatin@cs.duke.edu> To: Matt Dillon <dillon@earth.backplane.com> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: ecc on i386 Message-ID: <15279.55878.110154.650940@grasshopper.cs.duke.edu> In-Reply-To: <200109250058.f8P0wx998146@earth.backplane.com> References: <15279.54029.454089.299807@grasshopper.cs.duke.edu> <200109250058.f8P0wx998146@earth.backplane.com>
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Matt Dillon writes: > > :What happens on an ECC equipped PC when you have a multi-bit memory > :error that hardware scrubbing can't fix? Will there be some sort of > :NMI or something that will panic the box? > : > :I'm used to alphas (where you'll get a fatal machine check panic) and > :I am just wondering if PCs are as safe. > : > :Thanks, > : > :Drew > > ECC can typically detect and correct single bit errors and detect > double bit errors. Anything beyond that is problematic... it may or > may not detect the problem or may mis-correct a multi-bit error. > An NMI is generated if an uncorrectable error is detected. > > On PC's, ECC is optional. Desktops typically do not ship with ECC > memory. Branded servers typically do. A year or two ago I would > have been happy to use non-ECC rams (finding bad RAM through trial > and error), but now with capacities as they are and memory prices down > ECC is definitely the way to go. My sentiments exactly. > Bit errors can come from many sources, memory being only one. Bit errors > can occur inside the cpu chip, in the L1 and L2 caches, in memory, in > controller chips... all over the place. Many modern processors implement > parity on their caches to try to cover the problem areas. I'm not sure > how Pentium III's and IV's are setup. > > -Matt Hmm.. Well, it turns out that the box I"m insterested in (Thunder K7) can be set to send an SERR on multiple bit errors. I wonder what happens when a pc gets an SERR? (that's another machine check on alpha) Drew To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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