reproduce (this is a W=1 build):
        git remote add kdave https://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git
        git fetch kdave for-next
        git checkout kdave/for-next
        b4 shazam https://lore.kernel.org/r/efc4b5a3fbcbc7473afc228badd3e1306298bf33.1769290938.git.boris@bur.io

        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # apt-get install llvm-dev

        # save the config file
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 ARCH=i386 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 ARCH=i386 
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 headers
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 -C tools/testing/selftests