Messages in this thread | | | Subject | Re: NMI errors in 2.0.30??u | Date | Mon, 28 Apr 1997 15:23:44 +0200 (MET DST) | From | (Rogier Wolff) |
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Alan Cox wrote: > > > This test detects the simplest type of errors, and not much more. > > This test does not find all coupling errors that you describe. > > > > A more sofisticated test like marchg finds all errors, upto all the > > single coupling errors that may exist. > > Only if you blindly assume everything else is within spec. You should > do continual heavy DMA during all your testing. Lots of memory errors > don't show up except during DMA accesses where the cache is much > more stressed.
Yes, the DMA and "power supply interference" suggestions provide an explanation of why a normal memory test doesn't find most memory problems.
Indeed the "model" for the memory errors determines what the test will look like and what it is going to find. The question that always remains is: "Does the model conform to reality". In this case the answer is "no".
Although I know that a memory test is not going to find 90% of the memory errors, I might still want to write a kernel-option that does a memory test just after boot. Alan, (or anybody else,) would you know of a generic way to have DMA occurring concurrently with the memory test to trigger that type of errors? I'm afraid that this would be impossible right?
Roger.
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