[PATCH] doc: add mlx5 PMD flex item documentation

[Thomas Monjalon]

16/11/2021 15:51, Gregory Etelson:
> Describe firmware configuration requirements.
> List mlx5 hardware and PMD limitations.

That's a pity we missed documentation when adding the feature.
Please a line "Fixes".

[...]
> +- Flex item API:
> +
> +  - Firmware configuration: ``FLEX_PARSER_PROFILE_ENABLE=4 PROG_PARSE_GRAPH=1``.

This is not a limitation and it is redundant with the last part of this patch.

> +  - Hardware support: BlueField-2.

I think it should be a space: BlueField 2

> +  - Flex item is supported on PF only.
> +  - Hardware limits ``header_length_mask_width`` up to 6 bits.
> +  - Firmware supports 8 global sample fields. Each flex item allocates non-shared sample fields from that pool.

Please break lines after a dot.

> +  - Supported flex item can have 1 IN arc - ``eth`` or ``udp`` and up to 2 OUT arcs - ``ipv4`` or ``ipv6``.

Is "arc" defined somewhere?

> +  - Flex item fields (next_header, next_protocol, samples) do not participate in RSS hash functions.

Fields should be enclosed with quotes.

> +  - In RTE flex item configuration, ``next_header.field_base`` value must be byte aligned (multiple of 8).

Please don't say "RTE".

[...]
> +- enable dynamic flex parser for RTE flex item::

Again, please stop using "RTE". I really wonder why I see this in a lot of patches.
In user doc, it doesn't make sense at all.
If you really want to distinguish API and driver implementation, use "API".

> +
> +   FLEX_PARSER_PROFILE_ENABLE=4
> +   PROG_PARSE_GRAPH=1