Re: NMI errors in 2.0.30??

Matthias Urlichs (
6 May 1997 19:40:38 +0200 (Rogier Wolff) writes:
> >
> > This would take weeks to test a few megabytes of RAM!

> > it does to access a bunch of 0x00000000s. This would put a 1 kHz load
> > change on the power supply. What happends if the power supply has a
> > 1 kHz overshoot?? The voltage will bounce at a 1 kHz rate. If it gets
> > out of range during this modulation, RAM (any RAM anywhere) could lose
> > its data.
> Hey, this is indeed a possible scenario of why memory tests cannot
> find some errors, while kernel compiles do.
It gets worse. There's the fact, for instance, that your RAM tester only
tests the RAM/CPU data path. Surprise, there's also a PCI bus with
busmastering devices, and there is an ISA bus with DMA devices (floppy),
and all contend for CPU time and memory bandwidth.

Systems which fall flat on their face when user 1 compiles stuff, user 2
scans a NFS-mounted volume, and user 3 reads a floppy, but which are
rock-solid otherwise, might not be exactly common, but they _have_ been
observed. :-(

       The conservatism of tomorrow injected into the affairs of today.
               --A. Bierce
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