tree: https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git Wextra head: 5d0c476a9aa8d83304ee40320c1533a7443c6af5 commit: 51d8bbf29f744fc470126e3b0a5a64fd5c155f0d [31/32] kbuild: consolidate extra warnings in scripts/Makefile.extrawarn config: sparc-allyesconfig (attached as .config) compiler: sparc64-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/arnd/playground.git/commi... git remote add arnd-playground https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git git fetch --no-tags arnd-playground Wextra git checkout 51d8bbf29f744fc470126e3b0a5a64fd5c155f0d # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=sparc 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 >>): 46 | .name = "SUNW,???-????", | drivers/mtd/maps/sun_uflash.c:51:5: warning: no previous prototype for 'uflash_devinit' [-Wmissing-prototypes] 51 | int uflash_devinit(struct platform_device *op, struct device_node *dp) | ^~~~~~~~~~~~~~ -- 56 | static char *su_typev[] = { "su(???)", "su(mouse)", "su(kbd)", "su(serial)" }; | vim +46 drivers/mtd/maps/sun_uflash.c ^1da177e4c3f415 Linus Torvalds 2005-04-16 44 ^1da177e4c3f415 Linus Torvalds 2005-04-16 45 struct map_info uflash_map_templ = { ^1da177e4c3f415 Linus Torvalds 2005-04-16 @46 .name = "SUNW,???-????", ^1da177e4c3f415 Linus Torvalds 2005-04-16 47 .size = UFLASH_WINDOW_SIZE, ^1da177e4c3f415 Linus Torvalds 2005-04-16 48 .bankwidth = UFLASH_BUSWIDTH, ^1da177e4c3f415 Linus Torvalds 2005-04-16 49 }; ^1da177e4c3f415 Linus Torvalds 2005-04-16 50 :::::: The code at line 46 was first introduced by commit :::::: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Linux-2.6.12-rc2 :::::: TO: Linus Torvalds <torvalds(a)ppc970.osdl.org&gt; :::::: CC: Linus Torvalds <torvalds(a)ppc970.osdl.org&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org