--- old/src/hotspot/share/runtime/globals.hpp	2018-09-19 15:54:06.956275300 -0700
+++ new/src/hotspot/share/runtime/globals.hpp	2018-09-19 15:54:06.320971900 -0700
@@ -2612,7 +2612,10 @@
           "Start flight recording with options"))                           \
                                                                             \
   experimental(bool, UseFastUnorderedTimeStamps, false,                     \
-          "Use platform unstable time where supported for timestamps only")
+          "Use platform unstable time where supported for timestamps only") \
+                                                                            \
+  experimental(ccstr, AllocateOldGenAt, NULL,                               \
+               "Directory to use for allocating old generation")
 
 #define VM_FLAGS(develop,                                                   \
                  develop_pd,                                                \