Document handling of bad memory

March 2008

Jan-Simon Moeller, dl9pf@gmx.de

How to deal with bad memory e.g. reported by memtest86+ ?

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There are three possibilities I know of:

1) Reinsert/swap the memory modules

2) Buy new modules (best!) or try to exchange the memory

   if you have spare-parts

3) Use BadRAM or memmap

This Howto is about number 3) .

BadRAM

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BadRAM is the actively developed and available as kernel-patch

here:  http://rick.vanrein.org/linux/badram/

For more details see the BadRAM documentation.

memmap

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memmap is already in the kernel and usable as kernel-parameter at

boot-time.  Its syntax is slightly strange and you may need to

calculate the values by yourself!

Syntax to exclude a memory area (see kernel-parameters.txt for details):

memmap=<size>$<address>

Example: memtest86+ reported here errors at address 0x18691458, 0x18698424 and

         some others. All had 0x1869xxxx in common, so I chose a pattern of

         0x18690000,0xffff0000.

With the numbers of the example above:

memmap=64K$0x18690000

 or

memmap=0x10000$0x18690000