reproduce (this is a W=1 build):
        git checkout linus/master
        b4 shazam https://lore.kernel.org/r/20260204182816.2463931-1-sashal@kernel.org

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=um olddefconfig
        make W=1 O=build_dir ARCH=um SHELL=/bin/bash kernel/liveupdate/