reproduce:
        # https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=66c76c1cd984c14660453dfa2118014817924375
        git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
        git fetch --no-tags linux-next master
        git checkout 66c76c1cd984c14660453dfa2118014817924375
        # 1. reproduce by kismet
           # install kmax per https://github.com/paulgazz/kmax/blob/master/README.md
           kismet --linux-ksrc=linux --selectees CONFIG_LEDS_EXPRESSWIRE --selectors CONFIG_BACKLIGHT_KTD2801 -a=alpha
        # 2. reproduce by make
           # save the config file to linux source tree
           cd linux
           make ARCH=alpha olddefconfig