From: Vivek Goyal <vgoyal@in.ibm.com>

- elfcorehdr= specifies the location of elf core header stored by the
  crashed kernel.  This command line option will be passed by the kexec-tools
  to capture kernel.

Changes in this version :

- Added more comments in kernel-parameters.txt and in code.

Signed-off-by: Murali M Chakravarthy <muralim@in.ibm.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 Documentation/kernel-parameters.txt |    7 ++++---
 arch/x86_64/kernel/setup.c          |    9 +++++++++
 2 files changed, 13 insertions(+), 3 deletions(-)

diff -puN arch/x86_64/kernel/setup.c~kdump-x86_64-add-elfcorehdr-command-line-option arch/x86_64/kernel/setup.c
--- 25/arch/x86_64/kernel/setup.c~kdump-x86_64-add-elfcorehdr-command-line-option	2006-01-05 01:37:00.844623024 -0800
+++ 25-akpm/arch/x86_64/kernel/setup.c	2006-01-05 01:37:24.610010136 -0800
@@ -35,6 +35,7 @@
 #include <asm/processor.h>
 #include <linux/console.h>
 #include <linux/seq_file.h>
+#include <linux/crash_dump.h>
 #include <linux/root_dev.h>
 #include <linux/pci.h>
 #include <linux/acpi.h>
@@ -421,6 +422,14 @@ static __init void parse_cmdline_early (
 		}
 #endif
 
+#ifdef CONFIG_CRASH_DUMP
+		/* elfcorehdr= specifies the location of elf core header
+		 * stored by the crashed kernel. This option will be passed
+		 * by kexec loader to the capture kernel.
+		 */
+		else if(!memcmp(from, "elfcorehdr=", 11))
+			elfcorehdr_addr = memparse(from+11, &from);
+#endif
 	next_char:
 		c = *(from++);
 		if (!c)
diff -puN Documentation/kernel-parameters.txt~kdump-x86_64-add-elfcorehdr-command-line-option Documentation/kernel-parameters.txt
--- 25/Documentation/kernel-parameters.txt~kdump-x86_64-add-elfcorehdr-command-line-option	2006-01-05 01:37:00.846622720 -0800
+++ 25-akpm/Documentation/kernel-parameters.txt	2006-01-05 01:37:00.852621808 -0800
@@ -480,10 +480,11 @@ running once the system is up.
 			See Documentation/block/as-iosched.txt and
 			Documentation/block/deadline-iosched.txt for details.
 
-	elfcorehdr=	[IA-32]
+	elfcorehdr=	[IA-32, X86_64]
 			Specifies physical address of start of kernel core
-			image elf header.
-			See Documentation/kdump.txt for details.
+			image elf header. Generally kexec loader will
+			pass this option to capture kernel.
+			See Documentation/kdump/kdump.txt for details.
 
 	enforcing	[SELINUX] Set initial enforcing status.
 			Format: {"0" | "1"}
_