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    SubjectRe: [PATCH 2.6.24] mm: BadRAM support for broken memory
    Date
    V4 with checkpatch.pl done ...



    Start of Documentation for BadRAM/memmap -
    Reference: http://lkml.org/lkml/2008/3/2/42

    Signed-off-by: Jan-Simon Moeller <dl9pf@gmx.de>


    diff -up /dev/null bad-memory.txt
    --- /dev/null 2007-09-21 21:12:45.000000000 +0200
    +++ bad-memory.txt 2008-03-11 18:44:45.101344820 +0100
    @@ -0,0 +1,56 @@
    +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/
    +
    +It takes the patterns of memtest86+ as arguments to exclude the defective
    +areas of the memory.
    +
    +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.
    + This means exclusion of the area from 0x18690000 to 0x1869ffff
    + (which is a block of 64k).
    + My kernel-cmdline was: badram=0x18690000,0xffff0000
    +
    +There are efforts to bring BadRAM into mainline in some way, possibly using
    +memmap internally (maybe 2.6.26 ?).
    +Thread on lkml: http://lkml.org/lkml/2008/3/2/42
    +
    +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 different 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>
    +
    +With the numbers of the example above:
    +memmap=64K$0x18690000
    + or
    +memmap=0x10000$0x18690000
    +
    +TODO: Multiple areas to exclude using memmap ?
    +







    Add example of usage to memmap - evolved from thread about BadRAM inclusion.

    Signed-off-by: Jan-Simon Moeller <dl9pf@gmx.de>


    diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
    index 533e67f..f25da88 100644
    --- a/Documentation/kernel-parameters.txt
    +++ b/Documentation/kernel-parameters.txt
    @@ -1131,6 +1131,10 @@ and is between 256 and 4096 characters. It is defined in the file
    memmap=nn[KMG]$ss[KMG]
    [KNL,ACPI] Mark specific memory as reserved.
    Region of memory to be used, from ss to ss+nn.
    + Example: Exclude memory from 0x18690000-0x1869ffff
    + memmap=64K$0x18690000
    + or
    + memmap=0x10000$0x18690000

    meye.*= [HW] Set MotionEye Camera parameters
    See Documentation/video4linux/meye.txt.

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