Re: [dpdk-dev] [PATCH 1/2] ethdev: announce flow API action PORT_ID changes

[Eli Britstein <elibr@nvidia.com>]

On 8/1/2021 1:22 PM, Andrew Rybchenko wrote:
> External email: Use caution opening links or attachments
>
>
> By its very name, action PORT_ID means that packets hit an ethdev with the
> given DPDK port ID. At least the current comments don't state the opposite.
> That said, since port representors had been adopted, applications like OvS
> have been misusing the action. They misread its purpose as sending packets
> to the opposite end of the "wire" plugged to the given ethdev, for example,
> redirecting packets to the VF itself rather than to its representor ethdev.
> Another example: OvS relies on this action with the admin PF's ethdev port
> ID specified in it in order to send offloaded packets to the physical port.
>
> Since there might be applications which use this action in its valid sense,
> one can't just change the documentation to greenlight the opposite meaning.
>
> The documentation must be clarified and rte_flow_action_port_id structure
> should be extended to support both meanings.

I think the only clarification needed is that PORT_ID acts as if 
rte_eth_tx_burst is called with the specified port-id.

Regarding representors, it's not different. When using TX on a 
representor port, the packets appear as RX on its represented port.

Please elaborate if there is a use case for the PORT_ID~ in which the 
app can get the packets using rte_eth_rx_burst on the specified port-id.

>
> Signed-off-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
> ---
>   doc/guides/rel_notes/deprecation.rst | 5 +++++
>   1 file changed, 5 insertions(+)
>
> diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
> index d9c0e65921..6e6413c89f 100644
> --- a/doc/guides/rel_notes/deprecation.rst
> +++ b/doc/guides/rel_notes/deprecation.rst
> @@ -158,3 +158,8 @@ Deprecation Notices
>   * security: The functions ``rte_security_set_pkt_metadata`` and
>     ``rte_security_get_userdata`` will be made inline functions and additional
>     flags will be added in structure ``rte_security_ctx`` in DPDK 21.11.
> +
> +* ethdev: Definition of the flow API action PORT_ID is ambiguous and needs
> +  clarification. Structure rte_flow_action_port_id will be extended to
> +  specify traffic direction to represented entity or ethdev port itself in
> +  DPDK 21.11.
> --
> 2.30.2
>