reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/ksinyuk/linux.git/commit/?id=6fa42e05f7e63d41ade0e59fa5d94ca8028f7887
        git remote add ksinyuk https://git.kernel.org/pub/scm/linux/kernel/git/ksinyuk/linux.git
        git fetch --no-tags ksinyuk drm-tip
        git checkout 6fa42e05f7e63d41ade0e59fa5d94ca8028f7887

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=um olddefconfig
        make W=1 O=build_dir ARCH=um SHELL=/bin/bash