--- old/share/gc/cms/cmsArguments.cpp	2018-06-15 09:47:35.474912372 -0700
+++ new/share/gc/cms/cmsArguments.cpp	2018-06-15 09:47:35.418912371 -0700
@@ -86,6 +86,10 @@
   assert(!UseSerialGC && !UseParallelOldGC && !UseParallelGC, "Error");
   assert(UseConcMarkSweepGC, "CMS is expected to be on here");
 
+  if (AllocateOldGenAt != NULL) {
+    vm_exit_during_initialization("The flag -XX:AllocateOldGenAt can not be used with CMS. Only ParallelOldGC and G1GC are supported.", NULL);
+  }
+
   // CMS space iteration, which FLSVerifyAllHeapreferences entails,
   // insists that we hold the requisite locks so that the iteration is
   // MT-safe. For the verification at start-up and shut-down, we don't