diff --git a/[refs] b/[refs]
index c93b9ae79509..105ead5659d2 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: b13761ecd1d9977d2083da243e051e9f29097aef
+refs/heads/master: b783fd925cdd56d24d164e5bdcb072f2a67aedf4
diff --git a/trunk/Documentation/x86_64/boot-options.txt b/trunk/Documentation/x86_64/boot-options.txt
index 6887d44d2661..6da24e7a56cb 100644
--- a/trunk/Documentation/x86_64/boot-options.txt
+++ b/trunk/Documentation/x86_64/boot-options.txt
@@ -238,6 +238,13 @@ Debugging
   pagefaulttrace Dump all page faults. Only useful for extreme debugging
 		and will create a lot of output.
 
+  call_trace=[old|both|newfallback|new]
+		old: use old inexact backtracer
+		new: use new exact dwarf2 unwinder
+ 		both: print entries from both
+		newfallback: use new unwinder but fall back to old if it gets
+			stuck (default)
+
 Misc
 
   noreplacement  Don't replace instructions with more appropriate ones