> Were you > thinking of user-facing documentation, or more on the code side?
I'm not 100% sure, maybe code side is enough. With the current patch, the behavior is only visible if somebody intentionally tries to make it visible, and even then it's not really harmful. In the code it's definitely worth mentioning since it's not trivial, and stating it also makes it clear that it's not a bug/oversight. It could be also useful info if another patch later wants to also use timing_clock_source to keep in mind that users can change it dynamically.
