reproduce:
        # https://git.kernel.org/pub/scm/linux/kernel/git/leon/linux-rdma.git/commit/?id=fd6a83d0d7b4aba0032f93ea9c03613a0ba09a19
        git remote add leon-rdma https://git.kernel.org/pub/scm/linux/kernel/git/leon/linux-rdma.git
        git fetch --no-tags leon-rdma rxe-rust-v1
        git checkout fd6a83d0d7b4aba0032f93ea9c03613a0ba09a19
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        # pip install -r Documentation/sphinx/requirements.txt
        make htmldocs