Re: [dpdk-dev] FW: Issues with ixgbe and rte_flow

[Le Scouarnec Nicolas <Nicolas.LeScouarnec@technicolor.com>]

Hi Adrien,

>On Wed, Mar 15, 2017 at 02:29:44PM +0000, Le Scouarnec Nicolas wrote:
>> Overall, as a user, I feel one difficulty/complexity in using the API comes from the need to
>> specify both the stack of protocol (in type) and at each level the "next protocol type" of the header (in spec).
>>
>> Then, the PMD has to check that what I specified as the "next protocol type" is coherent with the protocol
>> stack before setting up the filters. Basically, for a valid filter, I should always have
>> rte_flow_item[1].type == rte_flow_item[0].spec.type, and  rte_flow_item[2].type == rte_flow_item[1].spec.{type,next_protocol}
>>  (except for L2.5 protocol as I experienced, which makes thinks confusing). Couldn't the API leverage this fact so that I don't
>> need to specify the ether_type, TPID, next_protocol_id, ... which are redundant with rte_flow_item.type ?

>Just to be clear, as a user you don't *need* to provide them, however the
>API certainly does not prevent you to do so. Only masked fields are
>relevant, and the default item masks (rte_flow_item_*_mask) do not include
>protocol types because as you're pointing out, that would indeed be a pain.

>Is the documentation not clear enough regarding this?
>(see "8.2.3 Pattern item")

To me it wasn't clear that the PMD/DPDK would take care of "type" fields in network headers for me,
hence, I tried to set them correctly (and got it wrong for ether_type/tpid) -- I feared that filtering on VLAN tci
without restricting to VLAN packets (setting ether_type) would be undefined behavior. I just check ixgbe_flow and
as you said it just ignores the types and relies on the stack so my previous comment and suggestion
was wrong.

The documentation is very clear on struct and how to use them, but a few common examples (in C) would have been useful to me;
for example I could have noticed that the example never set the ether_type & cie. testpmd is hard to read as an example.

> I think adding custom types would be more complicated than the current
> approach of leaving the payload type field unspecified or set it to some
> custom value that PMDs may or may not accept depending on their
> capabilities.

You're right. My comment was based on the misconception that it was mandatory to correctly specify ether_types / next_protocol_id / ...

Best regards.