reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git/commit/?id=387f31e96d46cd6ba0cf6b2439c367440f60255f
        git remote add rdma https://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git
        git fetch --no-tags rdma wip/jgg-for-next
        git checkout 387f31e96d46cd6ba0cf6b2439c367440f60255f

        # 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 drivers/infiniband/hw/bnxt_re/