--- a/src/hotspot/share/runtime/vm_version.hpp	Tue Aug 20 10:46:23 2019 +0200
+++ b/src/hotspot/share/runtime/vm_version.hpp	Tue Aug 20 10:11:53 2019 +0100
@@ -67,6 +67,7 @@
   static int          _vm_security_version;
   static int          _vm_patch_version;
   static int          _vm_build_number;
+  static unsigned int _data_cache_line_flush_size;
 
   static VirtualizationType _detected_virtualization;
 
@@ -155,6 +156,18 @@
     return _L1_data_cache_line_size;
   }
 
+  // the size in bytes of a data cache line flushed by a flush
+  // operation which should be a power of two or zero if cache line
+  // writeback is not supported by the current os_cpu combination
+  static unsigned int data_cache_line_flush_size() {
+    return _data_cache_line_flush_size;
+  }
+
+  // returns true if and only if cache line writeback is supported
+  static bool supports_data_cache_line_flush() {
+    return _data_cache_line_flush_size != 0;
+  }
+
   // ARCH specific policy for the BiasedLocking
   static bool use_biased_locking()  { return true; }