--- a/src/share/vm/runtime/virtualspace.hpp	Fri Jul 11 01:14:44 2008 -0700
+++ b/src/share/vm/runtime/virtualspace.hpp	Sat Jul 19 17:38:22 2008 -0400
@@ -29,13 +29,15 @@
  private:
   char*  _base;
   size_t _size;
+  size_t _noaccess_prefix;
   size_t _alignment;
   bool   _special;
 
   // ReservedSpace
   ReservedSpace(char* base, size_t size, size_t alignment, bool special);
   void initialize(size_t size, size_t alignment, bool large,
-                  char* requested_address = NULL);
+                  char* requested_address,
+                  const size_t noaccess_prefix);
 
   // Release parts of an already-reserved memory region [addr, addr + len) to
   // get a new region that has "compound alignment."  Return the start of the
@@ -59,13 +61,19 @@
                           const size_t suffix_size,
                           const size_t suffix_align);
 
+ protected:
+  // Create protection page at the beginning of the space.
+  void protect_noaccess_prefix(const size_t size);
+
  public:
   // Constructor
   ReservedSpace(size_t size);
   ReservedSpace(size_t size, size_t alignment, bool large,
-                char* requested_address = NULL);
+                char* requested_address = NULL,
+                const size_t noaccess_prefix = 0);
   ReservedSpace(const size_t prefix_size, const size_t prefix_align,
-                const size_t suffix_size, const size_t suffix_align);
+                const size_t suffix_size, const size_t suffix_align,
+                const size_t noaccess_prefix);
 
   // Accessors
   char*  base()      const { return _base;      }
@@ -73,6 +81,8 @@
   size_t alignment() const { return _alignment; }
   bool   special()   const { return _special;   }
 
+  size_t noaccess_prefix()   const { return _noaccess_prefix;   }
+
   bool is_reserved() const { return _base != NULL; }
   void release();
 
@@ -104,6 +114,16 @@
   return last_part(partition_size, alignment());
 }
 
+// Class encapsulating behavior specific of memory space reserved for Java heap
+class ReservedHeapSpace : public ReservedSpace {
+public:
+  // Constructor
+  ReservedHeapSpace(size_t size, size_t forced_base_alignment,
+                    bool large, char* requested_address);
+  ReservedHeapSpace(const size_t prefix_size, const size_t prefix_align,
+                    const size_t suffix_size, const size_t suffix_align);
+};
+
 // VirtualSpace is data structure for committing a previously reserved address range in smaller chunks.
 
 class VirtualSpace VALUE_OBJ_CLASS_SPEC {