On Mon, Jan 31, 2022 at 11:21:08AM +0100, Miroslav Lichvar wrote:

I tried to find the discussion around this decision, but failed. Do
you have a link?

I'll dig it up for you.
 

To me, it seems very strange to start the PHC at 0. It makes the
initial clock correction unnecessarily larger by ~7 orders of
magnitude. The system clock is initialized from the RTC, which can
have an error comparable to the TAI-UTC offset, especially if the
machine was turned off for a longer period of time, so why not
initialize the PHC from the system time? The error is much smaller
than billions of seconds.

When the clock reads Jan 1, 1970, then that is clearly wrong, and so a
user might suspect that it is uninititalized.

When the clock is off by 37 seconds, the user will likely post a vague
complaint to linuxptp-users asking why linuxptp doesn't handle leap
seconds.

I prefer the clarity of the first case.

Thanks,
Richard