> -----Original Message----- > From: Richardson, Bruce <bruce.richard...@intel.com> > Sent: Friday, June 10, 2022 11:36 PM > To: dev@dpdk.org > Cc: Maxime Coquelin <maxime.coque...@redhat.com>; Xia, Chenbo > <chenbo....@intel.com>; Richardson, Bruce <bruce.richard...@intel.com>; > Stephen Hemminger <step...@networkplumber.org> > Subject: [PATCH v3 3/4] doc/howto: add code example to virtio-user > exception path doc > > 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 <bruce.richard...@intel.com> > Acked-by: Stephen Hemminger <step...@networkplumber.org> > --- > .../howto/virtio_user_as_exception_path.rst | 55 +++++++++++++++++++ > 1 file changed, 55 insertions(+) > > 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 > <https://doc.dpdk.org/api/rte__dev_8h.html#ad32e8eebf1f81ef9f290cb296b0c90 > bb>`_ > +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. > -- > 2.34.1
Acked-by: Chenbo Xia <chenbo....@intel.com>
