reproduce (this is a W=1 build):
        git remote add rust https://github.com/Rust-for-Linux/linux
        git fetch rust rust-next
        git checkout rust/rust-next
        b4 shazam https://lore.kernel.org/r/0102019cdb4c6a42-a28bbebb-3664-4792-966f-4036c94ac19c-000000@eu-west-1.amazonses.com

        # install um cross compiling tool for clang build
        # apt-get install binutils-um-linux-gnu
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-18 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=um olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-18 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=um SHELL=/bin/bash