[POWERPC] print backtrace when entering xmon

xmon does not print a backtrace per default. This is bad on systems with
USB keyboard, the most needed info about the crash is lost.
print a backtrace during the very first xmon entry.

Booting with xmon=nobt disables the autobacktrace functionality.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
index d7b2aedd89aa..5ad149b47e34 100644
--- a/arch/powerpc/Kconfig.debug
+++ b/arch/powerpc/Kconfig.debug
@@ -88,6 +88,8 @@ config XMON
           very early during boot. 'xmon=on' will just enable the xmon
           debugger hooks.  'xmon=off' will disable the debugger hooks
           if CONFIG_XMON_DEFAULT is set.
+          xmon will print a backtrace on the very first invocation.
+          'xmon=nobt' will disable this autobacktrace.
 
 config XMON_DEFAULT
         bool "Enable xmon by default"