[PATCH] doc: fix support table for ETH and VLAN flow items

[Ilya Maximets]

On 10/7/22 13:50, Ilya Maximets wrote:
> On 9/12/22 12:09, Thomas Monjalon wrote:
>> 16/03/2022 13:01, Ilya Maximets:
>>> 'has_vlan' attribute is only supported by sfc, mlx5 and cnxk.
>>> Other drivers doesn't support it.  Most of them (like i40e) just
>>> ignore it silently.  Some drivers (like mlx4) never had a full
>>> support of the eth item even before introduction of 'has_vlan'
>>> (mlx4 allows to match on the destination MAC only).
>>>
>>> Same for the 'has_more_vlan' flag of the vlan item.
>>>
>>> Changing the support level to 'partial' for all such drivers.
>>> This doesn't solve the issue, but at least marks the problematic
>>> drivers.
>>
>> You changed "eth" and "vlan" from "Y" to "P".
>> The field "has_vlan" is part of "rte_flow_item_eth",
>> and "has_more_vlan" is part of "rte_flow_item_vlan",
>> so I agree we need to change both items to "partial support".
>> It looks to be a good change, just needs to more explicit,
>> adding this kind of explanation about the fields.
> 
> I can add this to the commit message.  Should I also add
> some note alongside the table in that documentation page?
> 
>>
>> We missed this patch in 22.07, let's have some progress quickly.
> 
> It was a busy month + PTO, sorry I didn't get to that patch faster.
> 
>>
>>> Some details are available in:
>>>   https://bugs.dpdk.org/show_bug.cgi?id=958
>>
>> About rte_flow_item_eth.{src,dst}, I don't find a deprecation notice
>> about it in the history of the file doc/guides/rel_notes/deprecation.rst
> 
> It took some time to find the deprecation notice, but I did find it
> in the end.  It's in the doc/guides/rel_notes/deprecation.rst, and
> it says:
> 
> * ethdev: The flow API matching pattern structures, ``struct rte_flow_item_*``,
>   should start with relevant protocol header.
>   Some matching pattern structures implements this by duplicating protocol header
>   fields in the struct. To clarify the intention and to be sure protocol header
>   is intact, will replace those fields with relevant protocol header struct.
>   In v21.02 both individual protocol header fields and the protocol header struct
>   will be added as union, target is switch usage to the protocol header by time.
>   In v21.11 LTS, protocol header fields will be cleaned and only protocol header
>   struct will remain.
> 
>> This is what we have in the code:
>>     union {
>>         struct {
>>             /*
>>              * These fields are retained for compatibility.
>>              * Please switch to the new header field below.
>>              */
>>             struct rte_ether_addr dst; /**< Destination MAC. */
>>             struct rte_ether_addr src; /**< Source MAC. */
>>             rte_be16_t type; /**< EtherType or TPID. */
>>         };
>>         struct rte_ether_hdr hdr;
>>     };
>>
>> Do you think we should remove the old fields now?
> 
> From the OVS perspective, we do not care much.  OVS is still using
> old fields, but it's fairly simple change that we can do while moving
> to a new version of DPDK.
> 
> From the perspective of the API clarity, it's probably better to clean
> up these structures.

There seems to be some outstanding work still though:
  https://patches.dpdk.org/project/dpdk/patch/20210312110745.31721-1-ivan.malov@oktetlabs.ru/#129161

> 
> Best regards, Ilya Maximets.
> 
>>
>>> Fixes: 09315fc83861 ("ethdev: add VLAN attributes to ethernet and VLAN items")
>>> Cc: stable at dpdk.org
>>>
>>> Signed-off-by: Ilya Maximets <i.maximets at ovn.org>
>>
>>
>>
>