# HG changeset patch
# User Bernhard Walle <bwalle@suse.de>
# Date 1223916744 -7200
# Node ID 2860e7a5d481633aca345b07db28d95fdb04d649
# Parent  f4cf2ef3cc3e6414d7d9386de0ebf7d633cbfed5
Add documentation for "Extended crashkernel commandline"

As stated in https://bugzilla.novell.com/show_bug.cgi?id=430276,
document the extended crashkernel commandline syntax in
kdump(7).

diff --git a/doc/man/kdump.7.txt.in b/doc/man/kdump.7.txt.in
--- a/doc/man/kdump.7.txt.in
+++ b/doc/man/kdump.7.txt.in
@@ -143,8 +143,7 @@
 
 [NOTE]
 There's also a more advanced syntax that makes the amount of memory dependent on
-system RAM. Read _Documentation/kernel-parameters.txt_ and
-_Documentation/kdump/kdump.txt_ of the kernel source for more information.
+system RAM. See <<crashkernel_exteded>>.
 
 Enable kdump service
 ~~~~~~~~~~~~~~~~~~~~
@@ -358,8 +357,36 @@
 If the problem is the *makedumpfile*(8) filtering tool, then set
 _MAKEDUMPFILE_OPTIONS_ to _-D_ to get debugging output of makedumpfile.
 
+Advanced Configuration
+----------------------
 
+[[crashkernel_exteded]]
+Extended crashkernel commandline
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
+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]
+
+while _start_ is inclusive and _end_ is exclusive.
+
+For example:
+
+    crashkernel=512M-2G:64M,2G-:128M
+
+This would mean:
+
+. If the RAM is smaller than 512M, then don't reserve anything
+  (this is the "rescue" case).
+. If the RAM size is between 512M and 2G (exclusive), then reserve 64M.
+. If the RAM size is larger than 2G, then reserve 128M.
 
 Bugs
 ----