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doc: update virtio prog guide

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This patch add contents for major change in single virtio implementation,
also add back something for merge-able feature and promiscuous mode in virtio.

Signed-off-by: Changchun Ouyang <changchun.ouyang@intel.com>
Acked-by: Siobhan Butler <siobhan.a.butler@intel.com>
This commit is contained in:
Ouyang Changchun 2015-03-02 16:40:47 +08:00 committed by Thomas Monjalon
parent 0d8d3df6b8
commit 227cce519f
1 changed files with 13 additions and 4 deletions
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17
doc/guides/prog_guide/poll_mode_drv_emulated_virtio_nic.rst
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@ -68,20 +68,29 @@ Features and Limitations of virtio PMD
In this release, the virtio PMD driver provides the basic functionality of packet reception and transmission.
* This release does not support mergeable buffers per packet for performance reasons.
The packet size supported is from 64 to 1518.
rte_mbuf should be big enough to hold the whole packet.
* It supports merge-able buffers per packet when receiving packets and scattered buffer per packet
when transmitting packets. The packet size supported is from 64 to 1518.
* It supports multicast packets and promiscuous mode.
* The descriptor number for the RX/TX queue is hard-coded to be 256 by qemu.
If given a different descriptor number by the upper application,
the virtio PMD generates a warning and fall back to the hard-coded value.
* Features such as mac/vlan filter are not supported.
* 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.
* RTE_PKTMBUF_HEADROOM should be defined larger than sizeof(struct virtio_net_hdr), which is 10 bytes.
* Virtio does not support runtime configuration.
* Virtio supports Link State interrupt.
* Virtio supports software vlan stripping and inserting.
* Virtio supports using port IO to get PCI resource when uio/igb_uio module is not available.
Prerequisites
-------------