[PATCH] i386/x86-64: Improve Kconfig description of CRASH_DUMP

Improve Kconfig description of CONFIG_CRASH_DUMP. Previously
it was too brief to be useful.

Cc: vgoyal@in.ibm.com
Cc: ebiederm@xmission.com
Signed-off-by: Andi Kleen <ak@suse.de>

arch/i386/Kconfig

@@ -761,6 +761,13 @@ config CRASH_DUMP
 	depends on HIGHMEM
 	help
 	  Generate crash dump after being started by kexec.
+          This should be normally only set in special crash dump kernels
+	  which are loaded in the main kernel with kexec-tools into
+	  a specially reserved region and then later executed after
+	  a crash by kdump/kexec. The crash dump kernel must be compiled
+          to a memory address not used by the main kernel or BIOS using
+          PHYSICAL_START.
+	  For more details see Documentation/kdump/kdump.txt
 
 config PHYSICAL_START
 	hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)

arch/x86_64/Kconfig

@@ -489,6 +489,13 @@ config CRASH_DUMP
 	depends on EXPERIMENTAL
 	help
           Generate crash dump after being started by kexec.
+          This should be normally only set in special crash dump kernels
+          which are loaded in the main kernel with kexec-tools into
+          a specially reserved region and then later executed after
+          a crash by kdump/kexec. The crash dump kernel must be compiled
+	  to a memory address not used by the main kernel or BIOS using
+	  PHYSICAL_START.
+          For more details see Documentation/kdump/kdump.txt
 
 config PHYSICAL_START
 	hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)