[PATCH] doc: update match with compare result item limitation

[Bing Zhao]

The ` repr_matching_en ` flag is enabled (by default) can be added.

> -----Original Message-----
> From: Suanming Mou <suanmingm at nvidia.com>
> Sent: Tuesday, November 5, 2024 9:48 AM
> To: Dariusz Sosnowski <dsosnowski at nvidia.com>; Slava Ovsiienko
> <viacheslavo at nvidia.com>; Bing Zhao <bingz at nvidia.com>; Ori Kam
> <orika at nvidia.com>; Matan Azrad <matan at nvidia.com>
> Cc: dev at dpdk.org; stable at dpdk.org
> Subject: [PATCH] doc: update match with compare result item limitation
> 
> In switch mode, when ``repr_matching_en`` flag is enabled in the devarg,
> the match with compare result item is not supported to the ``ingress``
> rule as an implicit REPRESENTED_PORT need to be added to the matcher.
> That REPRESENTED_PORT item conflicts with the single item limitation for
> match with compare result item.
> 
> Fixes: cb25df7ce9d6 ("net/mlx5: support comparison matching")
> Cc: stable at dpdk.org
> 
> Signed-off-by: Suanming Mou <suanmingm at nvidia.com>
> ---
>  doc/guides/nics/mlx5.rst | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst index
> 7ced6ca8f9..43ae9070ab 100644
> --- a/doc/guides/nics/mlx5.rst
> +++ b/doc/guides/nics/mlx5.rst
> @@ -460,6 +460,11 @@ Limitations
>    - The field type ``RTE_FLOW_FIELD_VALUE`` must be the base (``b``)
> field.
>    - The field type ``RTE_FLOW_FIELD_RANDOM`` can only be compared with
>      ``RTE_FLOW_FIELD_VALUE``.
> +  - In switch mode, when ``repr_matching_en`` flag is enabled in the
> devarg,
> +    the match with compare result item is not supported to the
> ``ingress``
> +    rule as an implicit REPRESENTED_PORT need to be added to the matcher.
> +    That REPRESENTED_PORT item conflicts with the single item limitation
> for
> +    match with compare result item.
> 
>  - No Tx metadata go to the E-Switch steering domain for the Flow group 0.
>    The flows within group 0 and set metadata action are rejected by
> hardware.
> --
> 2.34.1