[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>
diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig
index c134a54..e34a4db 100644
--- a/arch/i386/Kconfig
+++ b/arch/i386/Kconfig
@@ -761,6 +761,13 @@
 	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)