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On 11/30/06, Vladimir G. Ivanovic <vgivanovic@×××××××.net> wrote: |
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> I have done nothing to my hardware and I've seen this error, oh, a |
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> half a dozen times, the last time 3 months (?) ago. I ran memtest when |
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> I installed new memory, and it did not report problems even when run |
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> for hours. |
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|
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memtest is basically useless these days. It can only tell you if you |
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have a bad memory cell, which almost never happens today. Most memory |
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problems are the result of timing issues between the processor(s) and |
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DMA controllers. |
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|
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This script [1] seems to be a much better memory test for modern |
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systems, although you may have to make some tweaks to run it on |
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Gentoo. |
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|
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> And I do not get random segfaults with other programs. |
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|
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Yes, compiling is very unique in this regard. The memory access |
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pattern of a compiler, reading and writing to locations on different |
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rows, or even different modules, under high CPU load and using lots of |
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memory, with some IO thrown in for good measure, tends to reveal |
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hardware problems quite nicely. |
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|
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> Finally, I don't think my hardware fixed itself. |
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> |
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> Given all of this, my suspicion is that these errors are software |
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> bugs, not hardware problems. |
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|
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If we were talking about a driver, or an event-based GUI program, I |
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might agree. But a compiler is going to take the exact same actions |
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given the same input and options. The compiler isn't going to do |
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something different between 2 different executions over the _exact_ |
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same sources because it feels like it. |
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|
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> |
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> The other thing that I don't really believe is the part about "this |
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> bug not being reproducible" as reported by portage/emerge/make/gcc. |
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|
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Then you should read the gcc sources. One of the patches applied by |
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Gentoo adds a retry loop when the compiler is about to exit with an |
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internal compiler error (ICE). It retries the compile twice, and if |
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either of those succeeds, you get the "The bug is not reproducible" |
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message. It doesn't output anything because that would possibly |
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obscure the original error. |
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|
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The gentoo devs probably added this loop to avoid more duplicates of [2]. |
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|
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-Richard |
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|
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[1] http://people.redhat.com/dledford/memtest.html |
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[2] http://bugs.gentoo.org/show_bug.cgi?id=20600 |
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-- |
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