[PATCH] i386/x86-64: fall back to old-style call trace if no unwinding

If no unwinding is possible at all for a certain exception instance,
fall back to the old style call trace instead of not showing any trace
at all.

Also, allow setting the stack trace mode at the command line.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/asm-i386/unwind.h b/include/asm-i386/unwind.h
index 1c07689..d480f2e 100644
--- a/include/asm-i386/unwind.h
+++ b/include/asm-i386/unwind.h
@@ -66,10 +66,10 @@
 	info->regs.xes = __USER_DS;
 }
 
-extern asmlinkage void arch_unwind_init_running(struct unwind_frame_info *,
-                                                asmlinkage void (*callback)(struct unwind_frame_info *,
-                                                                            void *arg),
-                                                void *arg);
+extern asmlinkage int arch_unwind_init_running(struct unwind_frame_info *,
+                                               asmlinkage int (*callback)(struct unwind_frame_info *,
+                                                                          void *arg),
+                                               void *arg);
 
 static inline int arch_unw_user_mode(const struct unwind_frame_info *info)
 {