Puzzle for Doug...

[Robert G. Brown]

On Mon, 27 Jul 1998, Jess Johnson wrote:

> The BIOS memory test is a pretty pathetic memory test on 90% of pc's. Only
> on critical errors will it find anything wrong. I would suggest swapping it
> around to see if it makes a difference
> 
> Jess

Well, I saw the NMI error pop up on ANOTHER of the five systems
overnight, although this one recovered.  I have to say that I
seriously doubt that 3/5 of Dell's delivered systems have bad memory,
especially given that I've run these systems diskless for around 3
weeks now "flawlessly" under heavy load of big-memory applications.  A
memory problem with any significant probability of occurring (which
clearly must be the case, given that it happens at boot time in low
memory) would almost certainly have created havoc -- repeated kernel
crashes, bad answers, segment violation errors as loop/jump addresses
were corrupted -- none of which have been observed.  The phenomena
thus far seems confined to the aic7xxx driver only and moreso to the
7890 device -- I ran the old aic7xxx driver in diskless kernels for a
week or so (the one that found the 7860 but not the 7890) and observed
none of this.

It COULD be memory, and of course I'll (sigh) take down a box and see
if I can improve things (or at least change things) by swapping memory
out two banks at a time -- if I don't get a more promising response,
since I really don't think that it IS memory.  You can like Dell or
not as an "Intel/Microsoft lackey" (as a wag on the linux-smp list is
fond of calling them) but I really think that they do sell excellent,
if expensive, hardware.  I'd never expect a memory failure rate in the
10-20% range, which is what it would have to be to explain the
phenomena, and I'd further not expect to see only MARGINAL failures
instead of out and out won't boot the system period failures.

   rgb

Robert G. Brown	                       http://www.phy.duke.edu/~rgb/
Duke University Dept. of Physics, Box 90305
Durham, N.C. 27708-0305
Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu




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