Re: [gentoo-dev] SOLVED: Major MCE problem with SMP on Gentoo kernels

[Kevin]

Hi All-

A final note to this thread.

After trying for many hours of high-intensity cpu activity (like emerging 
many packages---which is what used to cause the MCE), since replacing my 
stepping level 7 Xeon with a stepping level 9 Xeon (so that I now have 
two identical cpus, even in stepping levels (whereas this was not true 
before), I have been unable to reproduce my MCE 0004 error.  I even did 
this with the kernel compiled with -march=pentium4 CFLAGS (that caused an 
MCE after 5 or 10 minutes of emerging mysql with stepping level 7 and 
stepping level 9 cpus installed).

Naturally, I'm delighted by this, however, the whole experience has been 
somewhat confusing (although enlightening in many respects).

Memtest86 still behaves exactly as it did before the hardware replacement.  
Any thoughts on why it behaves this way with this hardware (unable to set 
address range limits, unable to force ECC testing on, program locks after 
2 minutes of operation).  I suppose that's a question for another thread 
in another forum.

I seem to have suffered from no hardware failures on the M/B, the CPUs 
(one of the old CPUs is still present---I replaced the other), or the RAM 
(although I suppose the stepping level 7 Xeon might have had some 
incredibly subtle flaw that only showed up with another CPU present).

The replacement hardware seems to suffer no problems at all, in spite of 
what Memtest86 does (fails at 1023.8MB 30 or 40 times and then freezes).

I really appreciate all of the suggestions here.  You guys convinced me 
that it was hardware which is why I replaced everything and that 
ultimately solved the problem, although it's not clear that there was 
really a hardware problem.  The lesson I've learned (though I'm not sure 
this is really the root issue) is that when doing multi-processor 
computing, make sure that both processors are identical in every way.  
Any thoughts on the accuracy of this rule?

But the bizarre thing is that I couldn't reproduce this MCE at all using 
another distribution on the same (pre-replacement) hardware.  Does Gentoo 
push the hardware much harder than other distros?  Perhaps because I'm 
compiling the code for my particular hardware vice running code that was 
built to run on many different sets of hardware (less aggressive CFLAGS 
et. al.)?  I'm at a loss to explain this.

Again, many thanks for all the help here.

-Kevin

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