Hi Finn, First bad commit (maybe != root cause): tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: d895ec7938c431fe61a731939da76a6461bc6133 commit: 86ce436e30d86327c9f5260f718104ae7b21f506 macintosh/via-pmu: Fix build failure when CONFIG_INPUT is disabled date: 3 months ago config: powerpc-randconfig-r012-20220903 compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project c55b41d5199d2394dd6cdb8f52180d8b81d809d4) 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 # install powerpc cross compiling tool for clang build # apt-get install binutils-powerpc-linux-gnu # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=86ce436e30d86327c9f5260f718104ae7b21f506 git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git git fetch --no-tags linus master git checkout 86ce436e30d86327c9f5260f718104ae7b21f506 # save the config file mkdir build_dir && cp config build_dir/.config COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=powerpc SHELL=/bin/bash If you fix the issue, kindly add following tag where applicable Reported-by: kernel test robot All errors (new ones prefixed by >>): >> arch/powerpc/boot/decompress.c:132:8: error: call to undeclared function '__decompress'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration] ret = __decompress(inbuf, input_size, NULL, flush, outbuf, ^ 1 error generated. vim +/__decompress +132 arch/powerpc/boot/decompress.c 1b7898ee276b39 Oliver O'Halloran 2016-09-22 97 1b7898ee276b39 Oliver O'Halloran 2016-09-22 98 /** 1b7898ee276b39 Oliver O'Halloran 2016-09-22 99 * partial_decompress - decompresses part or all of a compressed buffer 1b7898ee276b39 Oliver O'Halloran 2016-09-22 100 * @inbuf: input buffer 1b7898ee276b39 Oliver O'Halloran 2016-09-22 101 * @input_size: length of the input buffer 930a77c3ad79c3 Zhang Jianhua 2021-05-10 102 * @outbuf: output buffer 930a77c3ad79c3 Zhang Jianhua 2021-05-10 103 * @output_size: length of the output buffer 1b7898ee276b39 Oliver O'Halloran 2016-09-22 104 * @skip number of output bytes to ignore 1b7898ee276b39 Oliver O'Halloran 2016-09-22 105 * 1b7898ee276b39 Oliver O'Halloran 2016-09-22 106 * This function takes compressed data from inbuf, decompresses and write it to 1b7898ee276b39 Oliver O'Halloran 2016-09-22 107 * outbuf. Once output_size bytes are written to the output buffer, or the 1b7898ee276b39 Oliver O'Halloran 2016-09-22 108 * stream is exhausted the function will return the number of bytes that were 1b7898ee276b39 Oliver O'Halloran 2016-09-22 109 * decompressed. Otherwise it will return whatever error code the decompressor 1b7898ee276b39 Oliver O'Halloran 2016-09-22 110 * reported (NB: This is specific to each decompressor type). 1b7898ee276b39 Oliver O'Halloran 2016-09-22 111 * 1b7898ee276b39 Oliver O'Halloran 2016-09-22 112 * The skip functionality is mainly there so the program and discover 1b7898ee276b39 Oliver O'Halloran 2016-09-22 113 * the size of the compressed image so that it can ask firmware (if present) 1b7898ee276b39 Oliver O'Halloran 2016-09-22 114 * for an appropriately sized buffer. 1b7898ee276b39 Oliver O'Halloran 2016-09-22 115 */ 1b7898ee276b39 Oliver O'Halloran 2016-09-22 116 long partial_decompress(void *inbuf, unsigned long input_size, 1b7898ee276b39 Oliver O'Halloran 2016-09-22 117 void *outbuf, unsigned long output_size, unsigned long _skip) 1b7898ee276b39 Oliver O'Halloran 2016-09-22 118 { 1b7898ee276b39 Oliver O'Halloran 2016-09-22 119 int ret; 1b7898ee276b39 Oliver O'Halloran 2016-09-22 120 1b7898ee276b39 Oliver O'Halloran 2016-09-22 121 /* 1b7898ee276b39 Oliver O'Halloran 2016-09-22 122 * The skipped bytes needs to be included in the size of data we want 1b7898ee276b39 Oliver O'Halloran 2016-09-22 123 * to decompress. 1b7898ee276b39 Oliver O'Halloran 2016-09-22 124 */ 1b7898ee276b39 Oliver O'Halloran 2016-09-22 125 output_size += _skip; 1b7898ee276b39 Oliver O'Halloran 2016-09-22 126 1b7898ee276b39 Oliver O'Halloran 2016-09-22 127 decompressed_bytes = 0; 1b7898ee276b39 Oliver O'Halloran 2016-09-22 128 output_buffer = outbuf; 1b7898ee276b39 Oliver O'Halloran 2016-09-22 129 limit = output_size; 1b7898ee276b39 Oliver O'Halloran 2016-09-22 130 skip = _skip; 1b7898ee276b39 Oliver O'Halloran 2016-09-22 131 1b7898ee276b39 Oliver O'Halloran 2016-09-22 @132 ret = __decompress(inbuf, input_size, NULL, flush, outbuf, :::::: The code at line 132 was first introduced by commit :::::: 1b7898ee276b39e54d870dc4ef3374f663d0b426 powerpc/boot: Use the pre-boot decompression API :::::: TO: Oliver O'Halloran :::::: CC: Michael Ellerman -- 0-DAY CI Kernel Test Service https://01.org/lkp