reproduce (this is a W=1 build):
        # https://github.com/intel-lab-lkp/linux/commit/809c9f483b87854f5b7ede3ce9ac6e372855169c
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Fernando-Fernandez-Mancera/ipv4-introduce-CONFIG_IPV4-to-decouple-the-IPv4-stack/20260928-212957
        git checkout 809c9f483b87854f5b7ede3ce9ac6e372855169c

        # 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=$HOME/0day COMPILER=clang-17 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=um olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-17 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=um SHELL=/bin/bash fs/