BPF Unit Testing ================ Unit tests are very important before deploying the application to production. For BPF, bpf_prog_test_run() subcommand is designed for unit testing. User provides input data (e.g., packet) and input context, the bpf program will be executed in the kernel, and potentially modified packet and context are returned to the user space for checking. Currently, certain bpf programs with __sk_buff contexts, xdp programs and flow dissector programs are supported. For better BPF unit testing, firstly, we really want bpf_prog_test_run() to support all program types. Secondly, the current verification for only returning packets and contexts may not be enough. If the bpf program modifies a particular kernel data structure field, user may want to verify it is indeed changed without modifying bpf programs. Lastly, We may have some bpf helpers hard to support, e.g., bpf_redirect. We would like to discuss the above three issues so bpf unit testing can become much better. -- Yonghong
