--- ethertap.c.old	Thu May  4 20:31:21 2000
+++ ethertap.c	Wed Jun 21 13:14:18 2000
@@ -29,6 +29,8 @@
 #include <net/sock.h>
 #include <linux/netlink.h>
 
+#define ETHERTAP_MAX_MTU 65536	/* So we can send any IP packet unfragmented */
+
 /*
  *	Index to functions.
  */
@@ -39,6 +41,7 @@
 static int  ethertap_close(struct net_device *dev);
 static struct net_device_stats *ethertap_get_stats(struct net_device *dev);
 static void ethertap_rx(struct sock *sk, int len);
+static int  ethertap_change_mtu(struct net_device *dev, int new_mtu);
 #ifdef CONFIG_ETHERTAP_MC
 static void set_multicast_list(struct net_device *dev);
 #endif
@@ -98,6 +101,7 @@
 
 	ether_setup(dev);
 
+	dev->change_mtu = ethertap_change_mtu;
 	dev->tx_queue_len = 0;
 	dev->flags|=IFF_NOARP;
 	tap_map[dev->base_addr]=dev;
@@ -124,6 +128,20 @@
 		return -ENOBUFS;
 	}
 	netif_start_queue(dev);
+	return 0;
+}
+
+/*
+ *	Overide default eth_change_mtu handler to allow MTU to be
+ *	larger than 1500 (for example to simulate gigabit ethernet
+ *	Jumbo frames).
+ */
+ 
+static int ethertap_change_mtu(struct net_device *dev, int new_mtu)
+{
+	if ((new_mtu < 68) || (new_mtu > ETHERTAP_MAX_MTU))
+		return -EINVAL;
+	dev->mtu = new_mtu;
 	return 0;
 }