Hi Krzysztof, First bad commit (maybe != root cause): tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: dd860052c99b1e088352bdd4fb7aef46f8d2ef47 commit: 7a69a6f68da5084e7f42df18bbc3b38f3785cccf mfd: omap-usb: Depend on COMMON_CLK to fix compile tests date: 5 months ago config: mips-randconfig-c023-20210508 (attached as .config) compiler: mipsel-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://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit... git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git git fetch --no-tags linus master git checkout 7a69a6f68da5084e7f42df18bbc3b38f3785cccf # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross W=1 ARCH=mips 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: "rt_sysc_membase" [drivers/watchdog/rt2880_wdt.ko] undefined!