A mechanism to allow debuggers to trigger on a certain hotkey
(combination). Derived (generalized) from similar KDB work.

Signed-Off-By: Jan Beulich <jbeulich@novell.com>

Index: 2.6.14-nlkd/drivers/char/keyboard.c
===================================================================
--- 2.6.14-nlkd.orig/drivers/char/keyboard.c	2005-11-09 10:40:17.000000000 +0100
+++ 2.6.14-nlkd/drivers/char/keyboard.c	2005-11-07 09:39:05.000000000 +0100
@@ -39,6 +39,7 @@
 #include <linux/vt_kern.h>
 #include <linux/sysrq.h>
 #include <linux/input.h>
+#include <linux/kdebug.h>
 
 static void kbd_disconnect(struct input_handle *handle);
 extern void ctrl_alt_del(void);
@@ -153,6 +154,9 @@ static int sysrq_down;
 #endif
 static int sysrq_alt;
 
+struct notifier_block *kdebug_chain = NULL;
+EXPORT_SYMBOL(kdebug_chain);
+
 /*
  * Translation of scancodes to keycodes. We set them on only the first attached
  * keyboard - for per-keyboard setting, /dev/input/event is more useful.
@@ -1052,6 +1056,11 @@ static void kbd_keycode(unsigned int key
 
 	rep = (down == 2);
 
+	if (notify_kdebug(KDEBUG_KEYBOARD,
+	                  keycode | ((long)!down << (BITS_PER_LONG - 1)),
+	                  regs) == NOTIFY_STOP)
+		return;
+
 #ifdef CONFIG_MAC_EMUMOUSEBTN
 	if (mac_hid_mouse_emulate_buttons(1, keycode, down))
 		return;
Index: 2.6.14-nlkd/include/linux/kdebug.h
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ 2.6.14-nlkd/include/linux/kdebug.h	2005-11-09 10:25:16.000000000 +0100
@@ -0,0 +1,27 @@
+#ifndef _KDEBUG_H
+#define _KDEBUG_H
+
+/*
+ * This notifier is to replace hardcoded entries in e.g. the keyboard
+ * driver used by kernel debuggers.
+ */
+#include <linux/notifier.h>
+
+struct pt_regs;
+
+struct kdebug_args {
+	struct pt_regs *regs;
+	long data;
+};
+
+extern struct notifier_block *kdebug_chain;
+
+#define KDEBUG_KEYBOARD 1
+
+static inline int notify_kdebug(unsigned long event, long data, struct pt_regs *regs)
+{
+	struct kdebug_args args = { .regs=regs, .data = data };
+	return notifier_call_chain(&kdebug_chain, event, &args);
+}
+
+#endif