reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/ardb/linux.git/commit/?id=019a7844cc2a63d08a2b5f396f68e2c547224ae7
        git remote add ardb git://git.kernel.org/pub/scm/linux/kernel/git/ardb/linux.git
        git fetch --no-tags ardb x86-pic
        git checkout 019a7844cc2a63d08a2b5f396f68e2c547224ae7
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash