--- old/src/hotspot/share/memory/virtualspace.hpp	2017-11-03 11:29:25.909414674 -0700
+++ new/src/hotspot/share/memory/virtualspace.hpp	2017-11-03 11:29:25.630417095 -0700
@@ -37,6 +37,7 @@
   size_t _noaccess_prefix;
   size_t _alignment;
   bool   _special;
+  int    _fd_for_heap;
  private:
   bool   _executable;
 
@@ -115,7 +116,9 @@
   void establish_noaccess_prefix();
  public:
   // Constructor. Tries to find a heap that is good for compressed oops.
-  ReservedHeapSpace(size_t size, size_t forced_base_alignment, bool large);
+  // heap_allocation_directory is the path to the backing memory for Java heap. When set, Java heap will be allocated
+  // on the device which is managed by the file system where the directory resides.
+  ReservedHeapSpace(size_t size, size_t forced_base_alignment, bool large, const char* heap_allocation_directory = NULL);
   // Returns the base to be used for compression, i.e. so that null can be
   // encoded safely and implicit null checks can work.
   char *compressed_oop_base() { return _base - _noaccess_prefix; }