NetBSD-1.0 's BPF support

The error occurred when using tcpdump on NetBSD-1.0:

Prompt does not /dev/bpf0 this file. Create /dev/bpf0 This file directly after the tcpdump command or prompt error:

Combined with the results of the online search, it was finally determined that the kernel did not add BPF support. Add BPF support to the kernel and recompile:

The kernel compiles successfully, replaces the original kernel and restarts, and then runs the tcpdump command again:

OK, the problem is solved.