FreeBSD/Linux Kernel Cross Reference
sys/Documentation/bad_memory.txt

     March 2008
     Jan-Simon Moeller, dl9pf@gmx.de
     
     
     How to deal with bad memory e.g. reported by memtest86+ ?
     #########################################################
     
     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
    ######
    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
    ######
    
    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
    

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