Re: [dpdk-dev] [PATCH 1/4] doc: clarify RTE flow behaviour on port stop/start

[Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>]

On 7/21/21 6:55 PM, Martin Havlik wrote:
> It is now clearly stated that RTE flow rules can be
> created only after the port is started.
> 
> Signed-off-by: Martin Havlik <xhavli56@stud.fit.vutbr.cz>
> ---
>   doc/guides/nics/mlx5.rst | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst
> index f5b727c1ee..119d537adf 100644
> --- a/doc/guides/nics/mlx5.rst
> +++ b/doc/guides/nics/mlx5.rst
> @@ -1790,21 +1790,25 @@ Notes for rte_flow
>   ------------------
>   
>   Flows are not cached in the driver.
>   When stopping a device port, all the flows created on this port from the
>   application will be flushed automatically in the background.
>   After stopping the device port, all flows on this port become invalid and
>   not represented in the system.
>   All references to these flows held by the application should be discarded
>   directly but neither destroyed nor flushed.
>   
> -The application should re-create the flows as required after the port restart.
> +The application should re-create the flows as required after the port is
> +started again.
> +
> +Creating flows before port start is not permitted. All flows the application
> +wants to create have to be created after the port is started.

I'm not 100% sure that it is always OK for applications, but in an
attempt to make it OK we should:
  - mention isolated mode if application dislikes default flow rules and
    would like to control it
  - mention what happens if restart happens internally, e.g. in order to
    recover from broken state. I guess in this case we need an event and
    application must register callback and handle it.

>   
>   Notes for testpmd
>   -----------------
>   
>   Compared to librte_net_mlx4 that implements a single RSS configuration per
>   port, librte_net_mlx5 supports per-protocol RSS configuration.
>   
>   Since ``testpmd`` defaults to IP RSS mode and there is currently no
>   command-line parameter to enable additional protocols (UDP and TCP as well
>   as IP), the following commands must be entered from its CLI to get the same
>