--- old/src/hotspot/share/runtime/os.hpp	Tue Nov 14 05:34:49 2017
+++ new/src/hotspot/share/runtime/os.hpp	Tue Nov 14 05:34:47 2017
@@ -446,7 +446,15 @@
   static bool create_thread(Thread* thread,
                             ThreadType thr_type,
                             size_t req_stack_size = 0);
+  // The "main thread", also known as "starting thread", is the thread
+  // that loads/creates the JVM via JNI_CreateJavaVM
   static bool create_main_thread(JavaThread* thread);
+  // The primordial thread is the initial process thread. The java
+  // launcher nevers uses the primordial thread as the main thread, but
+  // applications that host the JVM directly may do so. Some platforms
+  // have to special-case handling of the primordial thread if it attaches
+  // to the VM.
+  static bool is_primordial_thread(void);
   static bool create_attached_thread(JavaThread* thread);
   static void pd_start_thread(Thread* thread);
   static void start_thread(Thread* thread);