[patch 7/7] Add documentation for extended crashkernel syntax

From: Bernhard Walle
Date: Tue Sep 25 2007 - 14:25:52 EST

This adds the documentation for the extended crashkernel syntax into

Signed-off-by: Bernhard Walle <bwalle@xxxxxxx>

Documentation/kdump/kdump.txt | 26 ++++++++++++++++++++++++++
Documentation/kernel-parameters.txt | 7 +++++++
2 files changed, 33 insertions(+)

--- a/Documentation/kdump/kdump.txt
+++ b/Documentation/kdump/kdump.txt
@@ -231,6 +231,32 @@ Dump-capture kernel config options (Arch
any space below the alignment point will be wasted.

+Extended crashkernel syntax
+While the "crashkernel=size[@offset]" syntax is sufficient for most
+configurations, sometimes it's handy to have the reserved memory dependent
+on the value of System RAM -- that's mostly for distributors that pre-setup
+the kernel command line to avoid a unbootable system after some memory has
+been removed from the machine.
+The syntax is:
+ crashkernel=<range1>:<size1>[,<range2>:<size2>,...][@offset]
+ range=start-[end]
+For example:
+ crashkernel=512M-2G:64M,2G-:128M
+This would mean:
+ 1) if the RAM is smaller than 512M, then don't reserve anything
+ (this is the "rescue" case)
+ 2) if the RAM size is between 512M and 2G, then reserve 64M
+ 3) if the RAM size is larger than 2G, then reserve 128M
Boot into System Kernel

--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -495,6 +495,13 @@ and is between 256 and 4096 characters.
[KNL] Reserve a chunk of physical memory to
hold a kernel to switch to with kexec on panic.

+ crashkernel=range1:size1[,range2:size2,...][@offset]
+ [KNL] Same as above, but depends on the memory
+ in the running system. The syntax of range is
+ start-[end] where start and end are both
+ a memory unit (amount[KMG]). See also
+ Documentation/kdump/kdump.txt for a example.
cs4232= [HW,OSS]
Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>

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