reproduce (this is a W=1 build):
        # https://github.com/kkdwivedi/linux/commit/9d11071a7f64de877aa38e4caaee708ac3ab67b7
        git remote add kkdwivedi https://github.com/kkdwivedi/linux
        git fetch --no-tags kkdwivedi arena-kptr
        git checkout 9d11071a7f64de877aa38e4caaee708ac3ab67b7

        # 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