Commit fb391599 authored by Bernhard Walle's avatar Bernhard Walle Committed by Linus Torvalds

Add documentation for extended crashkernel syntax

This adds the documentation for the extended crashkernel syntax into
Documentation/kdump/kdump.txt.
Signed-off-by: default avatarBernhard Walle <bwalle@suse.de>
Cc: Andi Kleen <ak@suse.de>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Vivek Goyal <vgoyal@in.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7d7712a3
......@@ -231,6 +231,32 @@ Dump-capture kernel config options (Arch Dependent, ia64)
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
=======================
......
......@@ -497,6 +497,13 @@ and is between 256 and 4096 characters. It is defined in the file
[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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