[PATCH] allow xmon=off on ppc64

[Olaf Hering]

If both CONFIG_XMON and CONFIG_XMON_DEFAULT is enabled in the .config,
there is no way to disable xmon again. setup_system calls first xmon_init,
later parse_early_param. So a new 'xmon=off' cmdline option will do the right
thing.

Signed-off-by: Olaf Hering <olh at suse.de>

 arch/ppc64/kernel/setup.c  |    8 +++++---
 arch/ppc64/xmon/start.c    |    2 +-
 arch/ppc64/xmon/xmon.c     |   26 ++++++++++++++++++--------
 include/asm-ppc64/system.h |    2 +-
 4 files changed, 25 insertions(+), 13 deletions(-)

Index: linux-2.6.12/arch/ppc64/kernel/setup.c
===================================================================
--- linux-2.6.12.orig/arch/ppc64/kernel/setup.c
+++ linux-2.6.12/arch/ppc64/kernel/setup.c
@@ -627,7 +627,7 @@ void __init setup_system(void)
 	 * Initialize xmon
 	 */
 #ifdef CONFIG_XMON_DEFAULT
-	xmon_init();
+	xmon_init(1);
 #endif
 	/*
 	 * Register early console
@@ -1350,11 +1350,13 @@ static int __init early_xmon(char *p)
 	/* ensure xmon is enabled */
 	if (p) {
 		if (strncmp(p, "on", 2) == 0)
-			xmon_init();
+			xmon_init(1);
+		if (strncmp(p, "off", 3) == 0)
+			xmon_init(0);
 		if (strncmp(p, "early", 5) != 0)
 			return 0;
 	}
-	xmon_init();
+	xmon_init(1);
 	debugger(NULL);
 
 	return 0;
Index: linux-2.6.12/arch/ppc64/xmon/start.c
===================================================================
--- linux-2.6.12.orig/arch/ppc64/xmon/start.c
+++ linux-2.6.12/arch/ppc64/xmon/start.c
@@ -27,7 +27,7 @@ static void sysrq_handle_xmon(int key, s
 			      struct tty_struct *tty) 
 {
 	/* ensure xmon is enabled */
-	xmon_init();
+	xmon_init(1);
 	debugger(pt_regs);
 }
 
Index: linux-2.6.12/arch/ppc64/xmon/xmon.c
===================================================================
--- linux-2.6.12.orig/arch/ppc64/xmon/xmon.c
+++ linux-2.6.12/arch/ppc64/xmon/xmon.c
@@ -2496,15 +2496,25 @@ static void dump_stab(void)
 	}
 }
 
-void xmon_init(void)
+void xmon_init(int enable)
 {
-	__debugger = xmon;
-	__debugger_ipi = xmon_ipi;
-	__debugger_bpt = xmon_bpt;
-	__debugger_sstep = xmon_sstep;
-	__debugger_iabr_match = xmon_iabr_match;
-	__debugger_dabr_match = xmon_dabr_match;
-	__debugger_fault_handler = xmon_fault_handler;
+	if (enable) {
+		__debugger = xmon;
+		__debugger_ipi = xmon_ipi;
+		__debugger_bpt = xmon_bpt;
+		__debugger_sstep = xmon_sstep;
+		__debugger_iabr_match = xmon_iabr_match;
+		__debugger_dabr_match = xmon_dabr_match;
+		__debugger_fault_handler = xmon_fault_handler;
+	} else {
+		__debugger = NULL;
+		__debugger_ipi = NULL;
+		__debugger_bpt = NULL;
+		__debugger_sstep = NULL;
+		__debugger_iabr_match = NULL;
+		__debugger_dabr_match = NULL;
+		__debugger_fault_handler = NULL;
+	}
 }
 
 void dump_segments(void)
Index: linux-2.6.12/include/asm-ppc64/system.h
===================================================================
--- linux-2.6.12.orig/include/asm-ppc64/system.h
+++ linux-2.6.12/include/asm-ppc64/system.h
@@ -88,7 +88,7 @@ DEBUGGER_BOILERPLATE(debugger_dabr_match
 DEBUGGER_BOILERPLATE(debugger_fault_handler)
 
 #ifdef CONFIG_XMON
-extern void xmon_init(void);
+extern void xmon_init(int enable);
 #endif
 
 #else