reproduce (this is a W=1 build): git clone https://github.com/intel/lkp-tests.git ~/lkp-tests # install s390 cross compiling tool for clang build # apt-get install binutils-s390x-linux-gnu # clang-21 might not be officially released. Try a lower version if installation fails. # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=751eedc4b4b79332ecf1a78c0dbeb47d573a8f59 git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git git fetch --no-tags linus master git checkout 751eedc4b4b79332ecf1a78c0dbeb47d573a8f59 # save the config file mkdir build_dir && cp config build_dir/.config COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-21 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=s390 olddefconfig COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-21 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=s390 SHELL=/bin/bash