Re: Deprecated packet modification flow actions

[Kevin Traynor <ktraynor@redhat.com>]

On 15/03/2024 09:24, Dariusz Sosnowski wrote:
>> NFP plans support RTE_FLOW_ACTION_TYPE_MODIFY_FIELD flow action in
>> 24.07 or 24.11.
>> For remove of legacy flow, does there also correspond patches in OVS project?
> I am not familiar with any patches to OVS. Thanks for raising this.
> 
> For the record, in latest commit on main branch in OVS (commit fa0dfa18d534) I see that the following modify actions are used:
> 
> RTE_FLOW_ACTION_TYPE_SET_MAC_SRC
> RTE_FLOW_ACTION_TYPE_SET_MAC_DST
> RTE_FLOW_ACTION_TYPE_SET_IPV4_SRC
> RTE_FLOW_ACTION_TYPE_SET_IPV4_DST
> RTE_FLOW_ACTION_TYPE_SET_TTL
> RTE_FLOW_ACTION_TYPE_SET_TP_SRC
> RTE_FLOW_ACTION_TYPE_SET_TP_DST
> RTE_FLOW_ACTION_TYPE_SET_IPV6_SRC
> RTE_FLOW_ACTION_TYPE_SET_IPV6_DST
> 
> We'd need to sync with OVS developers, but I assume we cannot just remove these without providing a proper replacement, so the functionality is not broken.

Yes, but I'd add that this is a general point about the API, regardless
of OVS or other projects.


> I think that, once there's an agreement on the timeline of implementing MODIFY_FIELD in PMDs, we'd need to work
> with OVS to migrate it to MODIFY_FIELD. After OVS uses MODIFY_FIELD actions, deprecated actions could be safely removed from OVS and DPDK.
> 

Ideally, there would be some overlap where both methods are present and
fully supported for a couple of releases. That would ease integration
for users, rather than having an abrupt switchover date.

OVS only takes DPDK LTS versions, so it could only take the next YY.11
release with this change.

Any OVS patches to switchover would need to be ready/reviewed in OVS
before the DPDK YY.11 release integration, otherwise it could delay
updating DPDK version and missing other new functionality/new drivers etc.

There is an OVS 'dpdk-latest' experimental branch that is paired with
head of DPDK main branch. You can send OVS patches to it for new DPDK
changes to refine and test with, in advance of a DPDK YY.11 release.

> What do you all think?
> > Also, this opens a question about other upstream projects using
deprecated actions. Do you know if there are other projects besides OVS?
> 

A quick search through some projects and I didn't see them used elsewhere.

thanks,
Kevin.

> Best regards,
> Dariusz Sosnowski
>