[RFC] lib/ethdev: introduce table driven APIs

[Jerin Jacob]

On Thu, Jun 15, 2023 at 7:36 PM Zhang, Qi Z <qi.z.zhang at intel.com> wrote:
>

> > > If we assume that the application is not P4-aware, it will consume existing
> > rte_flow API for flow offloading. In this case, all we need to do is implement
> > it in the PMD, which will be a highly hardware-specific task. Do you propose
> > generalizing this common part?
> > >
> > > On the other hand, if the application is P4-aware, we can assume that
> > there won't be a need for translation between P4 tokens and rte_flow
> > protocols in the PMD.
> >
> > I agree, Translation is BAD. There are two elements to that.
> > 1)if it is p4 aware application, why bother with DPDK abstraction?
> > 2)Can we use compiler techniques to avoid the cost of translation if P4-
> > aware path is needed in DPDK. Rather than creating yet another library. In
> > this context, that would translate to some of your compiler and FW work
> > making as generic so that _any_ other rte_flow based driver can use and
> > improve it.
>
>
> Ok, I would like to gain a better understanding. Below is my current understanding:
>
> There are no plans to introduce any new API from DPDK. However, your proposal suggests the creation of a tool, such as a compiler, which would assist in generating a translation layer from P4 table/actions to rte_flow for user application like p4 runtime backend that based on DPDK.
>
> Could you provide more details about the design? Specifically, I would like to know what the input for the compiler is and who is responsible for generating that input, as well as the process involved.
>
> I apologize if I have not grasped the complete picture, but I would appreciate your patience.

+ @Cristian Dumitrescu

There is already a lot of p4(just based on DPDK lib/pipeline SW, not
with any HW acceleration) with DPDK. Not sure how much it overlaps,
and how clean is this to integrate with existing SW or "create new
one"?
I would think, enhancing the current p4-dpdk support by using rte_flow
backend. That would translate to
1) Update https://github.com/p4lang/p4c/tree/main/backends/dpdk to
understand generic p4 table key token to rte_flow token for spec file
generation.
2) Update https://github.com/p4lang/p4-dpdk-target or introduce common
library in DPDK to map compiler output (spec file) to rte_flow objects
invocations.