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

[Magnus Danielson <[e-mail]>]

Hi Miroslav,

On 2021-01-04 17:44, Miroslav Lichvar wrote:
> On Mon, Jan 04, 2021 at 05:34:21PM +0100, Magnus Danielson wrote:
>>> It's been in the Linux kernel for years.
>>>        CLOCK_TAI (since Linux 3.10; Linux-specific)
>>>               A nonsettable system-wide clock derived from wall-clock
>>>               time but ignoring leap seconds.  This clock does not
>>>               experience discontinuities and backwards jumps caused by
>>>               NTP inserting leap seconds as CLOCK_REALTIME does.
>> Considering how long it's been in the kernel, I consider that for most
>> Linux systems, it can be used.
> 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.

Cheers,
Magnus