ETH_HEADER_ETHERTAP 44 arch/um/os-Linux/drivers/ethertap_kern.c skb->dev->mtu + 2 + ETH_HEADER_ETHERTAP); ETH_HEADER_ETHERTAP 247 arch/um/os-Linux/drivers/ethertap_user.c .max_packet = ETH_MAX_PACKET + ETH_HEADER_ETHERTAP,