path: root/Documentation/kdump
diff options
authorBernhard Walle <>2007-10-18 23:41:02 -0700
committerLinus Torvalds <>2007-10-19 11:53:51 -0700
commitfb391599f2eaf22197e3e914187c957ef7eeb4c5 (patch)
treedfb5a952526b8fc8957ff8502f1f79890f00175d /Documentation/kdump
parent7d7712a385d5b0a6f921dbd9b66ad3aaed387b5e (diff)
Add documentation for extended crashkernel syntax
This adds the documentation for the extended crashkernel syntax into Documentation/kdump/kdump.txt. Signed-off-by: Bernhard Walle <> Cc: Andi Kleen <> Cc: "Luck, Tony" <> Cc: Paul Mackerras <> Cc: Benjamin Herrenschmidt <> Cc: Paul Mundt <> Cc: Vivek Goyal <> Cc: "Eric W. Biederman" <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'Documentation/kdump')
1 files changed, 26 insertions, 0 deletions
diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
index 1b37b28cc234..d0ac72cc19ff 100644
--- a/Documentation/kdump/kdump.txt
+++ b/Documentation/kdump/kdump.txt
@@ -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