Has anybody used PTP time stamp hardware with NTP?

[James Browning]

On Fri, Dec 4, 2020, at 12:50 AM Hal Murray via devel <devel at ntpsec.org>
wrote:

>
> That should lead to better (earlier) time stamps.  It will bypass the
> interrupt response time and the coalesce delays.
>
> As I understand it, the catch is that the clock out near the network is
> not
> directly connected to the CPU clock so the time stamps from the hardware
> need
> to be translated to system time.
>
> I'm looking for a HOWTO type recipe for setting things up.
>

I found a question [1] that is tangential and led me to a
piece of documentation [2] and a PTP(ish) code sample [3]
that looks to be closer. It also looks like it might be
used in the ntpd/ntp_packetstamp.c code.

I didn't look very hard though.

[1]
https://networkengineering.stackexchange.com/questions/23369/how-to-check-if-a-nic-supports-hardware-timestamps
[2] https://www.kernel.org/doc/Documentation/networking/timestamping.txt
[3]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/testing/selftests/net/timestamping.c
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