net/ipv4: opt in for non-deliverable packet warning

kernel/drivers/net/stack/ipv4/Kconfig

@@ -62,5 +62,14 @@ config XENO_DRIVERS_NET_RTIPV4_ROUTER
 
     See Documentation/README.routing for further information.
 
+config XENO_DRIVERS_NET_RTIPV4_DEBUG
+    bool "RTipv4 Debugging"
+    depends on XENO_DRIVERS_NET_RTIPV4
+    default n
+    
+    ---help---
+    Enables debug message output of the RTipv4 layer. Typically, you
+    may want to turn this on for tracing issues in packet delivery.
+
 source "drivers/xenomai/net/stack/ipv4/udp/Kconfig"
 # source "drivers/xenomai/net/stack/ipv4/tcp/Kconfig"

kernel/drivers/net/stack/ipv4/ip_input.c

@@ -105,7 +105,8 @@ static inline void rt_ip_local_deliver(struct rtskb *skb)
         rt_ip_fallback_handler(skb);
 #endif /* CONFIG_XENO_DRIVERS_NET_ADDON_PROXY */
     } else {
-        rtdm_printk("RTnet: no protocol found\n");
+	if (IS_ENABLED(CONFIG_XENO_DRIVERS_NET_RTIPV4_DEBUG))
+		rtdm_printk("RTnet: no protocol found\n");
         kfree_rtskb(skb);
     }
 }