From patchwork Fri Jun 10 15:35:34 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bruce Richardson X-Patchwork-Id: 112662 X-Patchwork-Delegate: maxime.coquelin@redhat.com Return-Path: X-Original-To: patchwork@inbox.dpdk.org Delivered-To: patchwork@inbox.dpdk.org Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 6D630A0553; Fri, 10 Jun 2022 17:36:07 +0200 (CEST) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 328B142B6C; Fri, 10 Jun 2022 17:36:00 +0200 (CEST) Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by mails.dpdk.org (Postfix) with ESMTP id 4185C42B6C for ; Fri, 10 Jun 2022 17:35:58 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1654875358; x=1686411358; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=CMc4LufIXW6efKJTm//sSVSO7PVgBMdOuyNeLRYUgqo=; b=hIcan9JYpOPoxIeHvYPkb7cY7v3m9FoxcMz/L+6zdZhmyf8d2lgNdhFk WLa98VFkRaoDipVZZPhz1MNef6XndkvVVpY/wwojBl5h1DzaJZnMZF0Ej iCDXTgmjrl/QkJXga8UiU9jcBpRiwttHODjqvmDpAwYuF6MH3KyEoldy5 ovyNgN3an7LRGz9WyYf8+xgmjLsRZou9paynag7ISZMaBFYxKdygw/RXr ZTn14i3vk83NkzU5UgZboot0bJ86q85dbvDxPBLGMlz+y0TW2lO1M1GQR Zk1z1PyP+Y6rVdCew2ENdIx9thVujWBSJlHf/34gHpwE4vu0MBIUa2JsN w==; X-IronPort-AV: E=McAfee;i="6400,9594,10374"; a="276439978" X-IronPort-AV: E=Sophos;i="5.91,290,1647327600"; d="scan'208";a="276439978" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Jun 2022 08:35:57 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.91,290,1647327600"; d="scan'208";a="610761251" Received: from silpixa00401385.ir.intel.com (HELO silpixa00401385.ger.corp.intel.com.) ([10.237.223.181]) by orsmga008.jf.intel.com with ESMTP; 10 Jun 2022 08:35:56 -0700 From: Bruce Richardson To: dev@dpdk.org Cc: Maxime Coquelin , Chenbo Xia , Bruce Richardson , Stephen Hemminger Subject: [PATCH v3 3/4] doc/howto: add code example to virtio-user exception path doc Date: Fri, 10 Jun 2022 16:35:34 +0100 Message-Id: <20220610153535.659076-4-bruce.richardson@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220610153535.659076-1-bruce.richardson@intel.com> References: <20220527162659.129022-1-bruce.richardson@intel.com> <20220610153535.659076-1-bruce.richardson@intel.com> MIME-Version: 1.0 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 The HOWTO guide for using virtio-user as an exception path to the kernel only provided an example of how testpmd may be used for that purpose. However, a real application wanting to use virtio-user as exception path would likely want to create such devices from code within the app itself. Therefore, we update the doc with instructions and a code snippet showing how this may be done. Signed-off-by: Bruce Richardson Acked-by: Stephen Hemminger Acked-by: Chenbo Xia Reviewed-by: Maxime Coquelin --- .../howto/virtio_user_as_exception_path.rst | 55 +++++++++++++++++++ 1 file changed, 55 insertions(+) -- 2.34.1 diff --git a/doc/guides/howto/virtio_user_as_exception_path.rst b/doc/guides/howto/virtio_user_as_exception_path.rst index a7f0d366fe..2af1778578 100644 --- a/doc/guides/howto/virtio_user_as_exception_path.rst +++ b/doc/guides/howto/virtio_user_as_exception_path.rst @@ -157,3 +157,58 @@ For example: /path/to/dpdk-testpmd --vdev=virtio_user0,path=/dev/vhost-net,queues=2,queue_size=1024 -- \ -i --tx-offloads=0x002c --enable-lro --txq=2 --rxq=2 --txd=1024 --rxd=1024 + +Creating Virtio-User Ports within an Application +------------------------------------------------ + +To use virtio-user ports within an application, +it is not necessary to explicitly initialize those ports using EAL arguments at startup. +Instead, one can use the generic EAL API +`rte_eal_hotplug_add `_ +function to create a new instance at startup. +For example, to create a basic virtio-user port, the following code could be used: + +.. code-block:: C + + rte_eal_hotplug_add("vdev", "virtio_user0", "path=/dev/vhost-net"); + +A fuller code example is shown below, where a virtio-user port, and hence kernel netdev, +is created for each NIC port discovered by DPDK. +Each virtio-user port is given the MAC address of its matching physical port +(assuming app was run without vdev args on commandline, so all ports auto-discovered are HW ones). +These new virtio-user netdevs will appear in the kernel port listings as ``virtio_user0``, +``virtio_user1``, etc., +based on the names passed in as ``iface=`` via the ``portargs`` parameter. + +.. code-block:: C + + nb_ports = rte_eth_dev_count_avail(); + + /* Create a vhost_user port for each physical port */ + unsigned port_count = 0; + RTE_ETH_FOREACH_DEV(portid) { + char portname[32]; + char portargs[256]; + struct rte_ether_addr addr = {0}; + + /* don't create virtio_user ports for other virtio_user ports */ + if (++port_count > nb_ports) + break; + + /* get mac address of physical port to use as mac of virtio_user port */ + rte_eth_macaddr_get(portid, &addr); + + /* set the name and arguments */ + snprintf(portname, sizeof(portname), "virtio_user%u", portid); + snprintf(portargs, sizeof(portargs), + "path=/dev/vhost-net,queues=1,queue_size=%u,iface=%s,mac=" RTE_ETHER_ADDR_PRT_FMT, + RX_RING_SIZE, portname, RTE_ETHER_ADDR_BYTES(&addr)); + + /* add the vdev for virtio_user */ + if (rte_eal_hotplug_add("vdev", portname, portargs) < 0) + rte_exit(EXIT_FAILURE, "Cannot create paired port for port %u\n", portid); + + } + +Once these virtio-user ports have been created in the loop, all ports, both physical and virtual, +may be initialized and used as normal in the application.