-.. BSD LICENSE
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- All rights reserved.
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- modification, are permitted provided that the following conditions
- are met:
-
- * Redistributions of source code must retain the above copyright
- notice, this list of conditions and the following disclaimer.
- * Redistributions in binary form must reproduce the above copyright
- notice, this list of conditions and the following disclaimer in
- the documentation and/or other materials provided with the
- distribution.
- * Neither the name of Intel Corporation nor the names of its
- contributors may be used to endorse or promote products derived
- from this software without specific prior written permission.
-
- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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- OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+.. SPDX-License-Identifier: BSD-3-Clause
+ Copyright(c) 2010-2015 Intel Corporation.
Poll Mode Driver for Emulated Virtio NIC
========================================
by default. Tx queue size is still hard-coded to be 256.
* Features of mac/vlan filter are supported, negotiation with vhost/backend are needed to support them.
- When backend can't support vlan filter, virtio app on guest should disable vlan filter to make sure
- the virtio port is configured correctly. E.g. specify '--disable-hw-vlan' in testpmd command line.
+ When backend can't support vlan filter, virtio app on guest should not enable vlan filter in order
+ to make sure the virtio port is configured correctly. E.g. do not specify '--enable-hw-vlan' in testpmd
+ command line.
* "RTE_PKTMBUF_HEADROOM" should be defined
no less than "sizeof(struct virtio_net_hdr_mrg_rxbuf)", which is 12 bytes when mergeable or
Virtio PMD Rx/Tx Callbacks
--------------------------
-Virtio driver has 3 Rx callbacks and 2 Tx callbacks.
+Virtio driver has 4 Rx callbacks and 3 Tx callbacks.
Rx callbacks:
Vector version without mergeable Rx buffer support, also fixes the available
ring indexes and uses vector instructions to optimize performance.
+#. ``virtio_recv_mergeable_pkts_inorder``:
+ In-order version with mergeable Rx buffer support.
+
Tx callbacks:
#. ``virtio_xmit_pkts``:
#. ``virtio_xmit_pkts_simple``:
Vector version fixes the available ring indexes to optimize performance.
+#. ``virtio_xmit_pkts_inorder``:
+ In-order version.
By default, the non-vector callbacks are used:
Vector callbacks will be used when:
-* ``txq_flags`` is set to ``VIRTIO_SIMPLE_FLAGS`` (0xF01), which implies:
+* ``txmode.offloads`` is set to ``0x0``, which implies:
* Single segment is specified.
Example of using the vector version of the virtio poll mode driver in
``testpmd``::
- testpmd -l 0-2 -n 4 -- -i --txqflags=0xF01 --rxq=1 --txq=1 --nb-cores=1
+ testpmd -l 0-2 -n 4 -- -i --tx-offloads=0x0 --rxq=1 --txq=1 --nb-cores=1
+
+In-order callbacks only work on simulated virtio user vdev.
+* For Rx: If mergeable Rx buffers is enabled and in-order is enabled then
+ ``virtio_xmit_pkts_inorder`` is used.
+
+* For Tx: If in-order is enabled then ``virtio_xmit_pkts_inorder`` is used.
Interrupt mode
--------------
notification of device configuration changes, especially link status (lsc).
Interrupt mode is translated into Rx interrupts in the context of DPDK.
+.. Note::
+
+ Virtio PMD already has support for receiving lsc from qemu when the link
+ status changes, especially when vhost user disconnects. However, it fails
+ to do that if the VM is created by qemu 2.6.2 or below, since the
+ capability to detect vhost user disconnection is introduced in qemu 2.7.0.
+
Prerequisites for Rx interrupts
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ l3fwd-power -l 0-1 -- -p 1 -P --config="(0,0,1)" \
--no-numa --parse-ptype
+
+
+Virtio PMD arguments
+--------------------
+
+The user can specify below argument in devargs.
+
+#. ``vdpa``:
+
+ A virtio device could also be driven by vDPA (vhost data path acceleration)
+ driver, and works as a HW vhost backend. This argument is used to specify
+ a virtio device needs to work in vDPA mode.
+ (Default: 0 (disabled))
+
+#. ``mrg_rxbuf``:
+
+ It is used to enable virtio device mergeable Rx buffer feature.
+ (Default: 1 (enabled))
+
+#. ``in_order``:
+
+ It is used to enable virtio device in-order feature.
+ (Default: 1 (enabled))
Code Review / deb_dpdk.git / blobdiff