In all up_initialize() functions, automatically initialize TUN driver is so configureded

arch/z80/src/common/up_initialize.c

@@ -45,6 +45,7 @@
 #include <nuttx/board.h>
 #include <nuttx/fs/fs.h>
 #include <nuttx/net/loopback.h>
+#include <nuttx/net/tun.h>
 
 #include <arch/board/board.h>
 
@@ -188,5 +189,11 @@ void up_initialize(void)
   (void)localhost_initialize();
 #endif
 
+#ifdef CONFIG_NET_TUN
+  /* Initialize the TUN device */
+
+  (void)tun_initialize();
+#endif
+
   board_led_on(LED_IRQSENABLED);
 }