reproduce:
        # apt-get install sparse
        # sparse version: v0.6.4-66-g0196afe1
        # https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git/commit/?id=941c541566a6784beff5ef54ed880c606e3a6225
        git remote add axboe-block https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git
        git fetch --no-tags axboe-block rw_iter
        git checkout 941c541566a6784beff5ef54ed880c606e3a6225
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=i386 olddefconfig
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=i386 SHELL=/bin/bash drivers/firmware/cirrus/ drivers/greybus/ drivers/hid/ drivers/hwmon/ drivers/iio/ drivers/input/serio/ drivers/leds/ drivers/md/bcache/ drivers/media/cec/core/ drivers/mmc/core/ drivers/rtc/ drivers/watchdog/