tree: https://github.com/shenki/linux microwatt-5.7 head: fdd5f44ff5120ffb3fe90c60f8f47dfd95139982 commit: 2472f2bbb237abeff9551c09d8764ac7daa8b8cd [2/8] powerpc/microwatt: Add early debug UART support for Microwatt config: powerpc-allyesconfig (attached as .config) compiler: powerpc64-linux-gcc (GCC) 9.3.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross git checkout 2472f2bbb237abeff9551c09d8764ac7daa8b8cd # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=powerpc If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>, old ones prefixed by <<): 107 | void potato_uart_init(void) | ^~~~~~~~~~~~~~~~ vim +/potato_uart_init +107 arch/powerpc/platforms/microwatt/setup.c 106 108 { 109 potato_uart_base = UART_BASE; 110 111 potato_uart_reg_write(POTATO_CONSOLE_CLOCK_DIV, potato_uart_divisor(PROC_FREQ, UART_FREQ)); 112 } 113 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org