Hi Vladimir, I love your patch! Yet something to improve: [auto build test ERROR on net-next/master] url: https://github.com/0day-ci/linux/commits/Vladimir-Oltean/tag_8021q-for-Oc... base: https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git 213b97b125808aa220ba460a7af09d8f3772f669 config: sh-allmodconfig (attached as .config) compiler: sh4-linux-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 # https://github.com/0day-ci/linux/commit/b0c94dae99772294285cc3219500b7302... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Vladimir-Oltean/tag_8021q-for-Ocelot-switches/20210119-004520 git checkout b0c94dae99772294285cc3219500b73026853e83 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=sh 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 >>, old ones prefixed by <<): ERROR: modpost: "ocelot_port_inject_frame" [drivers/net/ethernet/mscc/mscc_ocelot.ko] undefined! ERROR: modpost: "__delay" [drivers/net/mdio/mdio-cavium.ko] undefined! ERROR: modpost: "__udivdi3" [fs/btrfs/btrfs.ko] undefined! ERROR: modpost: "__umoddi3" [fs/btrfs/btrfs.ko] undefined! Kconfig warnings: (for reference only) WARNING: unmet direct dependencies detected for SND_ATMEL_SOC_PDC Depends on SOUND && !UML && SND && SND_SOC && SND_ATMEL_SOC && HAS_DMA Selected by - SND_ATMEL_SOC_SSC && SOUND && !UML && SND && SND_SOC && SND_ATMEL_SOC - SND_ATMEL_SOC_SSC_PDC && SOUND && !UML && SND && SND_SOC && SND_ATMEL_SOC && ATMEL_SSC --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org