reproduce (this is a W=1 build):
        # https://github.com/kkdwivedi/linux/commit/b9c38e0bd60f01bffa8cc5656fdd1e721b7bb4ec
        git remote add kkdwivedi https://github.com/kkdwivedi/linux
        git fetch --no-tags kkdwivedi arena-kptr
        git checkout b9c38e0bd60f01bffa8cc5656fdd1e721b7bb4ec

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash