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Subject[Patch 7/8] doc: update the kdump document

Update the document for kdump.

Signed-off-by: WANG Cong <>


Index: linux-2.6/Documentation/kdump/kdump.txt
--- linux-2.6.orig/Documentation/kdump/kdump.txt
+++ linux-2.6/Documentation/kdump/kdump.txt
@@ -147,6 +147,15 @@ System kernel config options
analysis tools require a vmlinux with debug symbols in order to read
and analyze a dump file.

+4) Enable "automatically reserve memory for kexec kernel" in
+ "Processor type and features."
+ This will let you to use "crashkernel=auto", instead of specifying
+ numbers for "crashkernel=". Note, you need to have enough memory.
+ The threshold and reserved memory size are arch-dependent.
Dump-capture kernel config options (Arch Independent)

@@ -266,6 +275,26 @@ This would mean:
2) if the RAM size is between 512M and 2G (exclusive), then reserve 64M
3) if the RAM size is larger than 2G, then reserve 128M

+Or you can use:
+ crashkernel=auto
+if you have enough memory. The threshold is 4G on ia64 and x86, 2G on powerpc,
+below which this won't work.
+The automatically reserved memory size would be 128M on x86_32, 128M or 256M
+on ppc, 1/32 of your physical memory size on x86_64 and ppc64 (but it will not
+grow if you have more than 128G memory). IA64 has its own policy, shown below:
+ Memory size Reserved memory
+ =========== ===============
+ [4G, 12G) 256M
+ [12G, 128G) 512M
+ [128G, 256G) 768M
+ [256G, 378G) 1024M
+ [378G, 512G) 1536M
+ [512G, 768G) 2048M
+ [768G, ) 3072M

Boot into System Kernel

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