tree: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2020.09.07a head: cccf684a1da846c3ff830d553bc4cf97bf779f48 commit: cccf684a1da846c3ff830d553bc4cf97bf779f48 [23/23] rcu-tasks: Mass of debug and fixes config: csky-defconfig (attached as .config) compiler: csky-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 git checkout cccf684a1da846c3ff830d553bc4cf97bf779f48 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=csky If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): csky-linux-ld: kernel/sched/core.o: in function `$d': core.c:(.text+0x1584): undefined reference to `n_rtt_sched' --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org