reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git/commit/?id=5f2710a4c2754c3c63bbe751fe1c54eb7f5c8441
        git remote add pci https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git
        git fetch --no-tags pci bwctrl
        git checkout 5f2710a4c2754c3c63bbe751fe1c54eb7f5c8441
        # 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 drivers/