Re: [Ntp] CLOCK_TAI (was NTPv5: big picture)

[Miroslav Lichvar <[e-mail]>]

On Mon, Jan 04, 2021 at 06:48:16PM +0100, Magnus Danielson wrote:
> > The Linux system TAI clock can be read by applications, but there is
> > no support for timestamping of packets with this clock, i.e. it is
> > currently not useful for NTP.
> 
> The hardware time-stamping support will support PTP-timescale, which has
> a know relationship to TAI. With whatever relationship there will be
> between NTPv5 transport time-scale and TAI, the PTP relationship will
> also be known and thus can be used.

With hardware timestamping there is a separate (hardware) clock used
for timestamping. It's not related to the CLOCK_TAI system clock
discussed here. I assume we don't want NTPv5 to require a hardware
clock.

NTP is used for synchronization of various clocks. Most of them are
based on UTC. NTPv5 cannot support only TAI.

-- 
Miroslav Lichvar