* Added an emergency key mechanism to the kernel, inspired by Jan Klötzke's

patch from about a year ago (I couldn't use any code of his yet, though,
  but there are a few things left). The emergency keys are triggered by
  pressing Alt-SysReq + key.
* By default, only Alt-SysReq+'d' is used as a means to deliberately enter
  the kernel debugger. F12 belongs to userland again, now :-)
* Debugger add-ons now have another optional method to implement their own
  emergency keys - 'd' for the debugger cannot be overridden, though.
* The mechanism can be turned off via a new kernel setting, so it's not that
  easy anymore to "crash" Haiku if you don't want to.
* Right now, the PS/2 driver, and the pre-input_server in-kernel debugger
  keyboard mini-driver support this, USB not yet.
* Minor cleanup.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@31660 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/debug.h

@@ -28,7 +28,11 @@
 #endif
 
 #define ASSERT_ALWAYS(x) \
-	do { if (!(x)) { panic("ASSERT FAILED (%s:%d): %s\n", __FILE__, __LINE__, #x); } } while (0)
+	do {																	\
+		if (!(x)) {															\
+			panic("ASSERT FAILED (%s:%d): %s\n", __FILE__, __LINE__, #x);	\
+		}																	\
+	} while (0)
 
 #define ASSERT_ALWAYS_PRINT(x, format...) \
 	do {																	\
@@ -66,10 +70,13 @@ struct debugger_module_info {
 	void (*enter_debugger)(void);
 	void (*exit_debugger)(void);
 
-	// io hooks
+	// I/O hooks
 	int (*debugger_puts)(const char *str, int32 length);
 	int (*debugger_getchar)(void);
 	// TODO: add hooks for tunnelling gdb ?
+
+	// Misc. hooks
+	bool (*emergency_key_pressed)(char key);
 };
 
 struct debugger_demangle_module_info {
@@ -113,7 +120,8 @@ extern void		debug_stop_screen_debug_output(void);
 extern void		debug_set_page_fault_info(addr_t faultAddress, addr_t pc,
 					uint32 flags);
 extern debug_page_fault_info* debug_get_page_fault_info();
-extern void debug_trap_cpu_in_kdl(bool returnIfHandedOver);
+extern void		debug_trap_cpu_in_kdl(bool returnIfHandedOver);
+extern bool		debug_emergency_key_pressed(char key);
 
 extern char		kgetc(void);
 extern void		kputs(const char *string);