reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/ast/bpf.git/commit/?id=14998d7229aae1c444cebe748b0610805f2d43f2
        git remote add ast-bpf https://git.kernel.org/pub/scm/linux/kernel/git/ast/bpf.git
        git fetch --no-tags ast-bpf arena
        git checkout 14998d7229aae1c444cebe748b0610805f2d43f2
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash