reproduce (this is a W=1 build):
        git remote add rafael-pm https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git
        git fetch rafael-pm linux-next
        git checkout rafael-pm/linux-next
        b4 shazam https://lore.kernel.org/r/20231009171839.12267-3-sumitg@nvidia.com
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=um SUBARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=um SUBARCH=i386 SHELL=/bin/bash