reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git/commit/?id=e72cfdcfc0ed8bd149ad2c16891b9998c25f47a0
        git remote add tglx-devel https://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git
        git fetch --no-tags tglx-devel x86/core
        git checkout e72cfdcfc0ed8bd149ad2c16891b9998c25f47a0
        # 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