Test whether these operations work in P4 DPDK

[jafingerhut]

And record the result in some table summarizing tested-working features of BMv2 and P4-DPDK. Report the results back to the DASH behavioral model work group. Consider expanding the table to include other open source P4 implementations like P4TC, P4-EBPF, etc., with the help of implementers of those targets.

• cloning a packet

  • and modifying the clone after it has been created, so it is different than the original packet, including truncation

• sending packets to a CPU port that causes them to become P4Runtime controller PacketIn messages

  • in particular, can cloned packets be sent to the control plane in this way?

• injecting packet into P4 data plane via P4Runtime controller sending a PacketOut message

  • and are such packets easily separable from packets received on "normal ports" in the P4 program, e.g. because their input port is equal to one of a small set of specially designated CPU ports (perhaps with a set size of 1)?

• digest message extern, including that digest messages become asynchronous messages over a P4Runtime API gRPC connection to the P4Runtime controller?

  • does the implementation support batching of multiple such digest messages into one controller message?
  • how many different Digest externs are supported for a single P4 program?

[jafingerhut]

I have learned that it is definitely supported to send packets from P4 DPDK to control plane code, and in the opposite direction, via a normal TAP interface, as long as the control plane software listens for packets received on that TAP interface, and/or sends packets to it. This is just a plain old normal TAP interface as far as P4 DPDK is concerned. The packets sent from the P4 DPDK software switch on such a normal TAP interface do not become PacketIn messages to the infrap4d P4Runtime API clients, and PacketOut messages from a P4Runtime API client do not become packets sent on such a TAP interface.

There might be a supported way for P4Runtime API clients of infrap4d to use PacketIn and PacketOut messages, but if so, I have not learned how to do so as of 2024-Mar-02.

As of 2024-Mar-02, this file https://github.com/p4lang/p4c/tree/main/backends/dpdk says that P4 DPDK does not support the Digest extern. As far as I know, that is accurate.

If packet mirroring works in P4 DPDK, I do not know how to configure those mirror sessions from a P4Runtime API client yet. P4 programs that use the PNA mirror_packet extern function compile, and become unique kinds of actions in the .spec files output by p4c-dpdk, but I do not know how to make that mirroring actually happen. Perhaps it is possible if you use Python TDI calls from the CLI with the bf_switchd process, but I have not verified that myself.