reproduce (this is a W=1 build):
        git remote add tip https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git
        git fetch tip x86/mm
        git checkout tip/x86/mm
        b4 shazam https://lore.kernel.org/r/20251121185530.21876-6-riel@surriel.com

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash