reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git/commit/?id=51646201e21cdf40aad3925f7742a8d2ac727f43
        git remote add robh https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git
        git fetch --no-tags robh cpufreq-compile-test
        git checkout 51646201e21cdf40aad3925f7742a8d2ac727f43
        # 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