--- a/src/share/vm/memory/universe.cpp	Sun Feb 03 17:12:31 2013 -0500
+++ b/src/share/vm/memory/universe.cpp	Mon Feb 04 08:26:02 2013 -0500
@@ -144,6 +144,7 @@
 NarrowPtrStruct Universe::_narrow_klass = { NULL, 0, true };
 address Universe::_narrow_ptrs_base;
 
+size_t          Universe::_class_metaspace_size;
 
 void Universe::basic_type_classes_do(void f(Klass*)) {
   f(boolArrayKlassObj());
@@ -689,8 +690,15 @@
     // Return specified base for the first request.
     if (!FLAG_IS_DEFAULT(HeapBaseMinAddress) && (mode == UnscaledNarrowOop)) {
       base = HeapBaseMinAddress;
-    } else if (total_size <= OopEncodingHeapMax && (mode != HeapBasedNarrowOop)) {
-      if (total_size <= NarrowOopHeapMax && (mode == UnscaledNarrowOop) &&
+
+    // If the total size and the metaspace size are small enough to allow
+    // UnscaledNarrowOop then just use UnscaledNarrowOop.
+    } else if ((total_size <= OopEncodingHeapMax) && (mode != HeapBasedNarrowOop) &&
+        (!UseCompressedKlassPointers ||
+          (((OopEncodingHeapMax - heap_size) + Universe::class_metaspace_size()) <= KlassEncodingMetaspaceMax))) {
+      // We don't need to check the metaspace size here because it is always smaller
+      // than total_size.
+      if ((total_size <= NarrowOopHeapMax) && (mode == UnscaledNarrowOop) &&
           (Universe::narrow_oop_shift() == 0)) {
         // Use 32-bits oops without encoding and
         // place heap's top on the 4Gb boundary
@@ -706,14 +714,24 @@
           base = (OopEncodingHeapMax - heap_size);
         }
       }
+
+    // See if ZeroBaseNarrowOop encoding will work for a heap based at
+    // (KlassEncodingMetaspaceMax - class_metaspace_size()).
+    } else if (UseCompressedKlassPointers && (mode != HeapBasedNarrowOop) &&
+        (Universe::class_metaspace_size() + HeapBaseMinAddress <= KlassEncodingMetaspaceMax) &&
+        (KlassEncodingMetaspaceMax + heap_size - Universe::class_metaspace_size() <= OopEncodingHeapMax)) {
+      base = (KlassEncodingMetaspaceMax - Universe::class_metaspace_size());
     } else {
-      // Can't reserve below 32Gb.
+      // UnscaledNarrowOop encoding didn't work, and no base was found for ZeroBasedOops or
+      // HeapBasedNarrowOop encoding was requested.  So, can't reserve below 32Gb.
       Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
     }
+
     // Set narrow_oop_base and narrow_oop_use_implicit_null_checks
     // used in ReservedHeapSpace() constructors.
     // The final values will be set in initialize_heap() below.
-    if (base != 0 && (base + heap_size) <= OopEncodingHeapMax) {
+    if ((base != 0) && ((base + heap_size) <= OopEncodingHeapMax) &&
+        (!UseCompressedKlassPointers || (base + Universe::class_metaspace_size()) <= KlassEncodingMetaspaceMax)) {
       // Use zero based compressed oops
       Universe::set_narrow_oop_base(NULL);
       // Don't need guard page for implicit checks in indexed
@@ -796,7 +814,9 @@
       tty->print("heap address: " PTR_FORMAT ", size: " SIZE_FORMAT " MB",
                  Universe::heap()->base(), Universe::heap()->reserved_region().byte_size()/M);
     }
-    if ((uint64_t)Universe::heap()->reserved_region().end() > OopEncodingHeapMax) {
+    if (((uint64_t)Universe::heap()->reserved_region().end() > OopEncodingHeapMax) ||
+        (UseCompressedKlassPointers &&
+        ((uint64_t)Universe::heap()->base() + Universe::class_metaspace_size() > KlassEncodingMetaspaceMax))) {
       // Can't reserve heap below 32Gb.
       // keep the Universe::narrow_oop_base() set in Universe::reserve_heap()
       Universe::set_narrow_oop_shift(LogMinObjAlignmentInBytes);
@@ -862,8 +882,8 @@
   // be compressed the same as instances.
   // Need to round class space size up because it's below the heap and
   // the actual alignment depends on its size.
-  size_t metaspace_size = align_size_up(ClassMetaspaceSize, alignment);
-  size_t total_reserved = align_size_up(heap_size + metaspace_size, alignment);
+  Universe::set_class_metaspace_size(align_size_up(ClassMetaspaceSize, alignment));
+  size_t total_reserved = align_size_up(heap_size + Universe::class_metaspace_size(), alignment);
   char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
 
   ReservedHeapSpace total_rs(total_reserved, alignment, UseLargePages, addr);
@@ -904,8 +924,8 @@
   // compressed oops is greater than the one used for compressed klass
   // ptrs, a metadata space on top of the heap could become
   // unreachable.
-  ReservedSpace class_rs = total_rs.first_part(metaspace_size);
-  ReservedSpace heap_rs = total_rs.last_part(metaspace_size, alignment);
+  ReservedSpace class_rs = total_rs.first_part(Universe::class_metaspace_size());
+  ReservedSpace heap_rs = total_rs.last_part(Universe::class_metaspace_size(), alignment);
   Metaspace::initialize_class_space(class_rs);
 
   if (UseCompressedOops) {