Re: document memmap option better and help people with bad memory

From: Jan-Simon Möller <dl9pf@xxxxxx>
Date: Thu, 13 Mar 2008 11:45:28 +0100

Nack ... See comments ..

Am Donnerstag, 13. März 2008 09:08:04 schrieb Pavel Machek:

Provide example for memmap exclude option (it is slightly strange an
non-trivial) and provide nice small HOWTO for people with bad memory.

Signed-off-by: Jan-Simon Moeller <dl9pf@xxxxxx>
Signed-off-by: Pavel Machek <pavel@xxxxxxx>

---
commit ec630f2291d7a3a154e22fa54cd74e5f6aa47f9a
tree 9cf33f9fcda3ea363061acebc971c37815f6c907
parent 456fc99ea933d38466ee25681908868cde3425c5
author Pavel <pavel@xxxxxxxxxx> Thu, 13 Mar 2008 09:06:15 +0100
committer Pavel <pavel@xxxxxxxxxx> Thu, 13 Mar 2008 09:06:15 +0100

Documentation/bad_memory.txt | 45
+++++++++++++++++++++++++++++++++++ Documentation/kernel-parameters.txt |
4 +++
2 files changed, 49 insertions(+), 0 deletions(-)

diff --git a/Documentation/bad_memory.txt b/Documentation/bad_memory.txt
new file mode 100644
index 0000000..df84162
--- /dev/null
+++ b/Documentation/bad_memory.txt
@@ -0,0 +1,45 @@
+March 2008
+Jan-Simon Moeller, dl9pf@xxxxxx
+
+
+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

Typo from me: ^^^ remove "the"

+here: http://rick.vanrein.org/linux/badram/
+
+For more details see the BadRAM documentation.

Example: memtest86+ <- was here ... and has its context here (BadRAM-Pattern
and so on) ...
Just switch the place.

+
+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.

</move>

+
+With the numbers of the example above:
+memmap=64K$0x18690000
+ or
+memmap=0x10000$0x18690000
+
diff --git a/Documentation/kernel-parameters.txt
b/Documentation/kernel-parameters.txt index 533e67f..f25da88 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1131,6 +1131,10 @@ and is between 256 and 4096 characters.
memmap=nn[KMG]$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.

Tnx, Pavel for inclusion.

Best regards,
Jan-Simon

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References:
- document memmap option better and help people with bad memory
  - From: Pavel Machek

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