Low-level stack frame changes.

kern/arch/sys161/dev/lamebus_machdep.c

@@ -42,6 +42,7 @@
 #include <mainbus.h>
 #include <sys161/bus.h>
 #include <lamebus/lamebus.h>
+#include <lamebus/ltrace.h>
 #include "autoconf.h"
 
 /*
@@ -275,6 +276,15 @@ mainbus_send_ipi(struct cpu *target)
 	lamebus_assert_ipi(lamebus, target);
 }
 
+/*
+ * Trigger the debugger.
+ */
+void
+mainbus_debugger(void)
+{
+	ltrace_stop(0);
+}
+
 /*
  * Interrupt dispatcher.
  */