Hi Jakub, I love your patch! Yet something to improve: [auto build test ERROR on net-next/master] url: https://github.com/0day-ci/linux/commits/Jakub-Kicinski/udp_tunnel-add-NI... base: https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git e80a07b244dd6726094da73d58537c131cc0b1a6 config: arm-spear6xx_defconfig (attached as .config) compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0 reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arm If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): arm-linux-gnueabi-ld: net/ethtool/tunnels.o: in function `ethnl_tunnel_info_fill_reply': arm-linux-gnueabi-ld: net/ethtool/tunnels.o: in function `ethnl_tunnel_info_doit': tunnels.c:(.text+0x4ec): undefined reference to `udp_tunnel_nic_ops' --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org