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phoenix |
There are several classic problems related to memory on Linux
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systems.
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1) There are some buggy motherboards which cannot properly
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deal with the memory above 16MB. Consider exchanging
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your motherboard.
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2) You cannot do DMA on the ISA bus to addresses above
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16M. Most device drivers under Linux allow the use
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of bounce buffers which work around this problem. Drivers
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that don't use bounce buffers will be unstable with
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more than 16M installed. Drivers that use bounce buffers
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will be OK, but may have slightly higher overhead.
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3) There are some motherboards that will not cache above
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a certain quantity of memory. If you have one of these
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motherboards, your system will be SLOWER, not faster
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as you add more memory. Consider exchanging your
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motherboard.
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All of these problems can be addressed with the "mem=XXXM" boot option
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(where XXX is the size of RAM to use in megabytes).
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It can also tell Linux to use less memory than is actually installed.
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See the documentation of your boot loader (LILO, loadlin, etc.) about
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how to pass options to the kernel.
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There are other memory problems which Linux cannot deal with. Random
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corruption of memory is usually a sign of serious hardware trouble.
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Try:
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* Reducing memory settings in the BIOS to the most conservative
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timings.
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* Adding a cooling fan.
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* Not overclocking your CPU.
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* Having the memory tested in a memory tester or exchanged
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with the vendor. Consider testing it with memtest86 yourself.
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* Exchanging your CPU, cache, or motherboard for one that works.
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* Disabling the cache from the BIOS.
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* Try passing the "mem=4M" option to the kernel to limit
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Linux to using a very small amount of memory.
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Other tricks:
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* Try passing the "no-387" option to the kernel to ignore
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a buggy FPU.
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* Try passing the "no-hlt" option to disable the potentially
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buggy HLT instruction in your CPU.
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