$OpenBSD: patch-include_private_pthread_stop_world_h,v 1.1 2013/06/01 21:05:28 kurt Exp $
--- include/private/pthread_stop_world.h.orig	Thu Aug  9 16:25:13 2012
+++ include/private/pthread_stop_world.h	Tue Mar 19 19:39:39 2013
@@ -18,8 +18,22 @@
 #ifndef GC_PTHREAD_STOP_WORLD_H
 #define GC_PTHREAD_STOP_WORLD_H
 
+#if defined(GC_OPENBSD_THREADS)
+
+# include <sys/param.h>
+
+/*
+ * Beginning with the 5.2 release, OpenBSD has kernel supported threads.
+ * Only the userland thread model needs a non-standard approach.
+ */
+# if defined(OpenBSD) && OpenBSD < 201211
+#   define GC_OPENBSD_UTHREADS 1
+# endif
+
+#endif /* GC_OPENBSD_THREADS */
+
 struct thread_stop_info {
-#   ifndef GC_OPENBSD_THREADS
+#   ifndef GC_OPENBSD_UTHREADS
       word last_stop_count;     /* GC_last_stop_count value when thread */
                                 /* last successfully handled a suspend  */
                                 /* signal.                              */
