Index: /trunk/src/VBox/Devices/Network/slirp/libslirp.h
===================================================================
--- /trunk/src/VBox/Devices/Network/slirp/libslirp.h	(revision 50670)
+++ /trunk/src/VBox/Devices/Network/slirp/libslirp.h	(revision 50671)
@@ -97,4 +97,16 @@
 
 /**
+ * This macrodefinition is shortcut for check of hosts where Slirp,
+ * receives notifications from host. For now it's Darwin only. But
+ * Main API has primitives for listening DNS change event since 4.3.
+ */
+#if (defined(RT_OS_DARWIN))
+# define HAVE_NOTIFICATION_FOR_DNS_UPDATE 1
+#else
+# define HAVE_NOTIFICATION_FOR_DNS_UPDATE 0
+#endif
+
+
+/**
  * This method help DrvNAT to select strategy: about VMRESUMEREASON_HOST_RESUME:
  * - proceed with link termination (we let guest track host DNS settings)