From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 813CBA0C42; Wed, 23 Jun 2021 19:32:02 +0200 (CEST) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id ECC8C40141; Wed, 23 Jun 2021 19:32:01 +0200 (CEST) Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by mails.dpdk.org (Postfix) with ESMTP id 2CD314003F for ; Wed, 23 Jun 2021 19:32:00 +0200 (CEST) IronPort-SDR: nsrsP0A4KH6LnAb5w92rGq0IpclSbWftOl9VJHKPTRvqxTLfCULF81H06w/CIkWzc9gBjMe3vz MmnRql8UhJYA== X-IronPort-AV: E=McAfee;i="6200,9189,10024"; a="204305820" X-IronPort-AV: E=Sophos;i="5.83,294,1616482800"; d="scan'208";a="204305820" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Jun 2021 10:31:58 -0700 IronPort-SDR: JEFhq5Ah93V6uiuCazx6G9DEJ84y6d/sCTsLpD4ApcI2v9YHTrq+dTyMNW4YHZVTRRIfgHdZEz 1BGTwwOteLZQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.83,294,1616482800"; d="scan'208";a="557048643" Received: from silpixa00399752.ir.intel.com (HELO silpixa00399752.ger.corp.intel.com) ([10.237.222.27]) by fmsmga001.fm.intel.com with ESMTP; 23 Jun 2021 10:31:56 -0700 From: Ferruh Yigit To: dev@dpdk.org, Keith Wiles Cc: Ferruh Yigit , Stephen Hemminger , Thomas Monjalon Date: Wed, 23 Jun 2021 18:31:42 +0100 Message-Id: <20210623173142.3803801-1-ferruh.yigit@intel.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: [dpdk-dev] [PATCH] doc: note KNI alternatives and deprecation plan X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Add a note that KNI kernel module will be moved to dpdk-kmods git repo and there is a long term plan to deprecate it. Also add some more details on the alternatives to KNI and cons of the KNI against these alternatives. Signed-off-by: Ferruh Yigit --- doc/guides/nics/tap.rst | 2 + .../prog_guide/kernel_nic_interface.rst | 38 +++++++++++++++++-- 2 files changed, 37 insertions(+), 3 deletions(-) diff --git a/doc/guides/nics/tap.rst b/doc/guides/nics/tap.rst index 3ce696b605d1..07315fe32422 100644 --- a/doc/guides/nics/tap.rst +++ b/doc/guides/nics/tap.rst @@ -1,6 +1,8 @@ .. SPDX-License-Identifier: BSD-3-Clause Copyright(c) 2016 Intel Corporation. +.. _TunTap_PMD: + Tun|Tap Poll Mode Driver ======================== diff --git a/doc/guides/prog_guide/kernel_nic_interface.rst b/doc/guides/prog_guide/kernel_nic_interface.rst index 1ce03ec1a374..29f8c92fd9d6 100644 --- a/doc/guides/prog_guide/kernel_nic_interface.rst +++ b/doc/guides/prog_guide/kernel_nic_interface.rst @@ -6,16 +6,48 @@ Kernel NIC Interface ==================== +.. Note:: + + KNI kernel module will be removed from main git repository to `dpdk-kmods `_ + repository by the `DPDK technical board decision `_. + Also there is a `long term plan `_ to deprecate the KNI. + + :ref:`virtio_user_as_exceptional_path` alternative is preferred way for + interfacing with Linux network stack as it is being in-kernel solution and + similar performance expectations. + The DPDK Kernel NIC Interface (KNI) allows userspace applications access to the Linux* control plane. -The benefits of using the DPDK KNI are: +KNI allows an interface with the kernel network stack and allows management of +DPDK ports using standard Linux net tools such as ``ethtool``, ``ifconfig`` and +``tcpdump``. + +Main use case of KNI is get/receive exception packets from/to Linux network +stack while main datapath IO is done bypassing the networking stack. + +There are other alternatives to KNI, all are available in the upstream Linux: + +#. :ref:`TunTap_PMD` as wrapper to `Linux tun/tap + `_ + +#. :ref:`virtio_user_as_exceptional_path` + +The benefits of using the DPDK KNI against alternatives are: * Faster than existing Linux TUN/TAP interfaces (by eliminating system calls and copy_to_user()/copy_from_user() operations. -* Allows management of DPDK ports using standard Linux net tools such as ethtool, ifconfig and tcpdump. +The cons of the DPDK KNI are: + +* It is out-of-tree Linux kernel module and it can't be distributed as binary as + part of OSV DPDK packages. This makes it harder to consume, although it is + always possible to compile it from the source code. + +* As it shares memory between userspace and kernelspace, and kernel part + directly uses input provided by userspace, it is not safe. This makes hard to + upstream the module. -* Allows an interface with the kernel network stack. +* Only a subset of control commands are supported by KNI. The components of an application using the DPDK Kernel NIC Interface are shown in :numref:`figure_kernel_nic_intf`. -- 2.31.1