reproduce (this is a W=1 build):
        git remote add rdma https://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git
        git fetch rdma for-next
        git checkout rdma/for-next
        b4 shazam https://lore.kernel.org/r/20251221233404.332108-2-yanjun.zhu@linux.dev

        # 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