CC: zx2c4(a)kernel.org CC: linux-kernel(a)vger.kernel.org TO: "Jason A. Donenfeld" <zx2c4(a)kernel.org&gt; CC: "Jean-Philippe Aumasson" <jeanphilippe.aumasson(a)gmail.com&gt; tree: git://git.kernel.org/pub/scm/linux/kernel/git/crng/random.git jd/preempt-rt head: e32d7768f472ed279c1c4a82bf8ba611d67db8e2 commit: 17e19ef79dd0e0ad4b7ec2831088282ddd7674cd [4/9] random: use linear min-entropy accumulation crediting config: x86_64-buildonly-randconfig-r002-20220207 (https://download.01.org/0day-ci/archive/20220209/202202091149.sGYokEQM-lk...) compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project e8bff9ae54a55b4dbfeb6ba55f723abbd81bf494) 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/crng/random.git/commit/?i... git remote add crng-random git://git.kernel.org/pub/scm/linux/kernel/git/crng/random.git git fetch --no-tags crng-random jd/preempt-rt git checkout 17e19ef79dd0e0ad4b7ec2831088282ddd7674cd # save the config file to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/ If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): drivers/char/random.c:1882:6: warning: no previous prototype for function 'add_hwgenerator_randomness' [-Wmissing-prototypes] void add_hwgenerator_randomness(const char *buffer, size_t count, ^ drivers/char/random.c:1882:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void add_hwgenerator_randomness(const char *buffer, size_t count, ^ static 1 warning generated. --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org