reproduce (this is a W=1 build):
        git checkout cd8a4cfa6bb43a441901e82f5c222dddc75a18a3
        b4 shazam https://lore.kernel.org/r/20250902-scratch-bobbyeshleman-devmem-tcp-token-upstream-v1-2-d946169b5550@meta.com
        # 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 net/ipv4/