The SIGTRAP signal is thrown from the kernel if EVENT_MASK (ptrace_event)
enables PTRACE_FORK. This new si_code helps debuggers to distinguish the
exact source of signal delivered for a debugger.
Another purpose of TRAP_CHLD is to retain the same behavior inside the
NetBSD kernel for process child traps and have an interface to monitor it.
Retrieving exact event and extended properties of process child trap is
available with PT_GET_PROCESS_STATE.
There is no behavior change for existing software.
This si_code value is NetBSD extension.
Sponsored by <The NetBSD Foundation>
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