[PATCH] Retrieve elfcorehdr address from command line

This patch adds support for retrieving the address of elf core header if one
is passed in command line.

Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

4 files changed, 16 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 560ff5ae3fd..f44bb5567c5 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -451,6 +451,10 @@ running once the system is up.
                         Format: {"as"|"cfq"|"deadline"|"noop"}
                         See Documentation/block/as-iosched.txt
                         and Documentation/block/deadline-iosched.txt for details.
+        elfcorehdr=     [IA-32]
+                        Specifies physical address of start of kernel core image
+                        elf header.
+                        See Documentation/kdump.txt for details.
 
         enforcing       [SELINUX] Set initial enforcing status.
                         Format: {"0" | "1"}
diff --git a/arch/i386/kernel/setup.c b/arch/i386/kernel/setup.c
index 8d58a053e12..7306353c520 100644
--- a/arch/i386/kernel/setup.c
+++ b/arch/i386/kernel/setup.c
@@ -44,6 +44,7 @@
 #include <linux/edd.h>
 #include <linux/nodemask.h>
 #include <linux/kexec.h>
+#include <linux/crash_dump.h>
 
 #include <video/edid.h>
 
@@ -881,6 +882,13 @@ static void __init parse_cmdline_early (char ** cmdline_p)
                         }
                 }
 #endif
+#ifdef CONFIG_CRASH_DUMP
+                /* elfcorehdr= specifies the location of elf core header
+                 * stored by the crashed kernel.
+                 */
+                else if (!memcmp(from, "elfcorehdr=", 11))
+                        elfcorehdr_addr = memparse(from+11, &from);
+#endif
 
                 /*
                  * highmem=size forces highmem to be exactly 'size' bytes.
diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
index 7d983b81742..3f25fd1eaa4 100644
--- a/include/linux/crash_dump.h
+++ b/include/linux/crash_dump.h
@@ -7,6 +7,7 @@
 #include <linux/device.h>
 #include <linux/proc_fs.h>
 
+extern unsigned long long elfcorehdr_addr;
 extern ssize_t copy_oldmem_page(unsigned long, char *, size_t,
                                                 unsigned long, int);
 #endif /* CONFIG_CRASH_DUMP */
diff --git a/kernel/crash_dump.c b/kernel/crash_dump.c
index 5a1e6d5d203..10b966c3744 100644
--- a/kernel/crash_dump.c
+++ b/kernel/crash_dump.c
@@ -15,6 +15,9 @@
 #include <asm/io.h>
 #include <asm/uaccess.h>
 
+/* Stores the physical address of elf header of crash image. */
+unsigned long long elfcorehdr_addr;
+
 /*
  * Copy a page from "oldmem". For this page, there is no pte mapped
  * in the current kernel. We stitch up a pte, similar to kmap_atomic.