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


Document handling of bad memory
Document handling of bad memory

Document how to deal with bad memory reported with memtest.

Signed-off-by: Jan-Simon Möller <36ded0fe241474e14ca49d9021f8ba3a70d78d60@gmx.de>
Signed-off-by: Pavel Machek <2375fa63e2908bb2df59f606483a3aa92321db7a@suse.cz>
Signed-off-by: Jonathan Corbet <b2ce64d5587c02f12e367eac59751145a0660c51@lwn.net>
