tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master head: c7d4c1fd91ab4a6d2620497921a9c6bf54650ab8 commit: 6e121df14ccd5ca5142a21759beda7f12db0002b [8930/10489] ARM: 9090/1: Map the lowmem and kernel separately config: arm-keystone_defconfig (attached as .config) compiler: arm-linux-gnueabi-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/next/linux-next.git/commi... git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git git fetch --no-tags linux-next master git checkout 6e121df14ccd5ca5142a21759beda7f12db0002b # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arm 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 >>): arch/arm/mm/mmu.c:118:13: warning: no previous prototype for 'init_default_cache_policy' [-Wmissing-prototypes] 118 | void __init init_default_cache_policy(unsigned long pmd) | ^~~~~~~~~~~~~~~~~~~~~~~~~ arch/arm/mm/mmu.c:1156:13: warning: no previous prototype for 'adjust_lowmem_bounds' [-Wmissing-prototypes] 1156 | void __init adjust_lowmem_bounds(void) | ^~~~~~~~~~~~~~~~~~~~ arch/arm/mm/mmu.c:1715:13: warning: no previous prototype for 'paging_init' [-Wmissing-prototypes] 1715 | void __init paging_init(const struct machine_desc *mdesc) | ^~~~~~~~~~~ In file included from include/linux/kernel.h:17, from include/linux/list.h:9, from include/linux/module.h:12, from arch/arm/mm/mmu.c:7: arch/arm/mm/mmu.c: In function 'paging_init': 5 | #define KERN_SOH "\001" /* ASCII Start Of Header */ | ^~~~~~ include/linux/printk.h:140:10: note: in definition of macro 'no_printk' 140 | printk(fmt, ##__VA_ARGS__); \ | ^~~ include/linux/kern_levels.h:15:20: note: in expansion of macro 'KERN_SOH' 15 | #define KERN_DEBUG KERN_SOH "7" /* debug-level messages */ | ^~~~~~~~ include/linux/printk.h:430:12: note: in expansion of macro 'KERN_DEBUG' 430 | no_printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__) | ^~~~~~~~~~ arch/arm/mm/mmu.c:1719:2: note: in expansion of macro 'pr_debug' 1719 | pr_debug("physical kernel sections: 0x%08x-0x%08x\n", | ^~~~~~~~ arch/arm/mm/mmu.c:1719:43: note: format string is defined here 1719 | pr_debug("physical kernel sections: 0x%08x-0x%08x\n", | ~~~^ | | | unsigned int | %08llx In file included from include/linux/kernel.h:17, from include/linux/list.h:9, from include/linux/module.h:12, from arch/arm/mm/mmu.c:7: include/linux/kern_levels.h:5:18: warning: format '%x' expects argument of type 'unsigned int', but argument 3 has type 'phys_addr_t' {aka 'long long unsigned int'} [-Wformat=] 5 | #define KERN_SOH "\001" /* ASCII Start Of Header */ | ^~~~~~ include/linux/printk.h:140:10: note: in definition of macro 'no_printk' 140 | printk(fmt, ##__VA_ARGS__); \ | ^~~ include/linux/kern_levels.h:15:20: note: in expansion of macro 'KERN_SOH' 15 | #define KERN_DEBUG KERN_SOH "7" /* debug-level messages */ | ^~~~~~~~ include/linux/printk.h:430:12: note: in expansion of macro 'KERN_DEBUG' 430 | no_printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__) | ^~~~~~~~~~ arch/arm/mm/mmu.c:1719:2: note: in expansion of macro 'pr_debug' 1719 | pr_debug("physical kernel sections: 0x%08x-0x%08x\n", | ^~~~~~~~ arch/arm/mm/mmu.c:1719:50: note: format string is defined here 1719 | pr_debug("physical kernel sections: 0x%08x-0x%08x\n", | ~~~^ | | | unsigned int | %08llx arch/arm/mm/mmu.c: At top level: arch/arm/mm/mmu.c:1748:13: warning: no previous prototype for 'early_mm_init' [-Wmissing-prototypes] 1748 | void __init early_mm_init(const struct machine_desc *mdesc) | ^~~~~~~~~~~~~ vim +5 include/linux/kern_levels.h 314ba3520e513a Joe Perches 2012-07-30 4 04d2c8c83d0e3a Joe Perches 2012-07-30 @5 #define KERN_SOH "\001" /* ASCII Start Of Header */ 04d2c8c83d0e3a Joe Perches 2012-07-30 6 #define KERN_SOH_ASCII '\001' 04d2c8c83d0e3a Joe Perches 2012-07-30 7 :::::: The code at line 5 was first introduced by commit :::::: 04d2c8c83d0e3ac5f78aeede51babb3236200112 printk: convert the format for KERN_<LEVEL> to a 2 byte pattern :::::: TO: Joe Perches <joe(a)perches.com&gt; :::::: CC: Linus Torvalds <torvalds(a)linux-foundation.org&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org