From 86b1ae38c0a62409dc862a28e3f08920f55f944b Mon Sep 17 00:00:00 2001
From: Hariprasad Nellitheertha <hari@in.ibm.com>
Date: Sat, 25 Jun 2005 14:58:25 -0700
Subject: [PATCH] kdump: sysrq trigger mechanism for kexec based crashdumps

Add a sysrq-trigger mechanism for kexec based crashdumps.  Alt-Sysrq-c
triggers a kexec based crashdump.

Signed-off-by: Hariprasad Nellitheertha <hari@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
 drivers/char/sysrq.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

(limited to 'drivers/char/sysrq.c')

diff --git a/drivers/char/sysrq.c b/drivers/char/sysrq.c
index f59f7cbd525..53b2c8fab00 100644
--- a/drivers/char/sysrq.c
+++ b/drivers/char/sysrq.c
@@ -35,6 +35,7 @@
 #include <linux/spinlock.h>
 #include <linux/vt_kern.h>
 #include <linux/workqueue.h>
+#include <linux/kexec.h>
 
 #include <asm/ptrace.h>
 
@@ -94,6 +95,21 @@ static struct sysrq_key_op sysrq_unraw_op = {
 };
 #endif /* CONFIG_VT */
 
+#ifdef CONFIG_KEXEC
+/* crashdump sysrq handler */
+static void sysrq_handle_crashdump(int key, struct pt_regs *pt_regs,
+				struct tty_struct *tty)
+{
+	crash_kexec();
+}
+static struct sysrq_key_op sysrq_crashdump_op = {
+	.handler	= sysrq_handle_crashdump,
+	.help_msg	= "Crashdump",
+	.action_msg	= "Trigger a crashdump",
+	.enable_mask	= SYSRQ_ENABLE_DUMP,
+};
+#endif
+
 /* reboot sysrq handler */
 static void sysrq_handle_reboot(int key, struct pt_regs *pt_regs,
 				struct tty_struct *tty) 
@@ -273,8 +289,12 @@ static struct sysrq_key_op *sysrq_key_table[SYSRQ_KEY_TABLE_LENGTH] = {
 		 it is handled specially on the sparc
 		 and will never arrive */
 /* b */	&sysrq_reboot_op,
-/* c */ NULL,
-/* d */	NULL,
+#ifdef CONFIG_KEXEC
+/* c */ &sysrq_crashdump_op,
+#else
+/* c */	NULL,
+#endif
+/* d */ NULL,
 /* e */	&sysrq_term_op,
 /* f */	&sysrq_moom_op,
 /* g */	NULL,
-- 
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