reproduce (this is a W=1 build):
        git remote add mptcp https://github.com/multipath-tcp/mptcp_net-next.git
        git fetch mptcp export
        git checkout mptcp/export
        b4 shazam https://lore.kernel.org/r/9c089a245833c43d55ec240be1b880909af849ce.1747730598.git.tanggeliang@kylinos.cn
        # 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 net/