diff -r 80abfee2afaf -r c9590e526d19 src/hotspot/share/runtime/arguments.cpp
--- a/src/hotspot/share/runtime/arguments.cpp	Tue Jun 25 16:34:08 2019 +0100
+++ b/src/hotspot/share/runtime/arguments.cpp	Tue Jun 25 09:41:03 2019 -0700
@@ -1815,6 +1815,10 @@
       // was not specified.
       if (reasonable_max > max_coop_heap) {
         if (FLAG_IS_ERGO(UseCompressedOops) && override_coop_limit) {
+          log_info(cds)("UseCompressedOops and UseCompressedClassPointers have been disabled due to"
+            " max heap " SIZE_FORMAT " > compressed oop heap " SIZE_FORMAT ". "
+            "Please check the setting of MaxRAMPercentage %5.2f."
+            ,(size_t)reasonable_max, (size_t)max_coop_heap, MaxRAMPercentage);
           FLAG_SET_ERGO(UseCompressedOops, false);
           FLAG_SET_ERGO(UseCompressedClassPointers, false);
         } else {