[fruffy]

P4 and eBPF are not really competing in the same space. eBPF/XDP is a virtual kernel machine that you can program in restricted C. P4 is a language that specifies how a device should process packets. So P4 is compiled down into a target (for example, a switch or NIC), which then executes the code as specified by the programmer. The nice part about P4, compared to just working with the devices, is that it establishes a standard reference format for administration and control of packet processing. For example, Google is using P4 to test their switches (they talk about it in their keynote in this workshop [0]).

The eBPF/XDP VM could be one of these P4 targets. You can write a P4 specification that is converted into eBPF byte code which is then loaded and executed. The reference P4 compiler even has a eBPF[1] and an XDP[2] back end. However, those are currently not well maintained. Another problem is that the code generated from P4 is not as efficient as manually crafted eBPF byte code. With a little care this is all easily solvable.

Disclaimer: I work in this space.

[0]: https://opennetworking.org/2021-p4-workshop-content/

[1]: https://github.com/p4lang/p4c/tree/main/backends/ebpf

[2]: https://github.com/vmware/p4c-xdp