reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/bp/bp.git/commit/?id=cf9dcdd287f3d175a9fafdadb944586333cb785c
        git remote add bp https://git.kernel.org/pub/scm/linux/kernel/git/bp/bp.git
        git fetch --no-tags bp tip-ras-core-WIP
        git checkout cf9dcdd287f3d175a9fafdadb944586333cb785c
        # 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/ras/