Hi Richard,
Thanks for your answer!
So if I understand correctly I can run
pmc -u -b 0 'GET TIME_STATUS_NP'
to get
sending: GET TIME_STATUS_NP
98f2b3.fffe.138691-0 seq 0 RESPONSE MANAGEMENT TIME_STATUS_NP
master_offset 14
ingress_time 1589869722179953606
cumulativeScaledRateOffset +0.000000000
scaledLastGmPhaseChange 0
gmTimeBaseIndicator 0
lastGmPhaseChange 0x0000'0000000000000000.0000
gmPresent true
gmIdentity 0080ea.fffe.bd9a70
locally on the machine with connected hardware (which should be enough for
now).
And compare ingress_time to the timestamp I get when I use the local
hardware clock (which I am not allowed to sync with ptp).
Or is ingress_time the wrong time to use if I am not syncing?
For now all I need is the exact difference between what PTP would deliver
compared to the local systemtime.
Thanks a lot!
regards
Werner
On Mon, May 18, 2020 at 4:06 PM Richard Cochran <richardcoch...@gmail.com>
wrote:
> On Mon, May 18, 2020 at 08:58:09AM +0200, Werner Macho wrote:
> > So my questions are:
> > Is there something I can call to get the very exact time without syncing
> > the hardware clock on the computer? (I 'only' need a exact timestamp
> > without considering the computers HW-clock)
> > Would this somehow also be possible to call on a directly connected
> > computer on LAN?
> > Or better: Is this even possible at all?
>
> If you need a time stamp from a over an Ethernet network, then you need to
> exchange Ethernet frames.
>
> But you are not allowed to do even that?
>
> Then you are out of luck.
>
>
> If you can run PTP, I suggest:
>
> 1. Run ptp4l using the --free_running=1 mode.
>
> 2. Figure the time offset between the local clock and the remote clock
> using TIME_STATUS_NP:
>
> # designed for use with gPTP and free_running
> master_offset 0
> ingress_time 0
> cumulativeScaledRateOffset +0.000000000
> scaledLastGmPhaseChange 0
> gmTimeBaseIndicator 0
> lastGmPhaseChange 0x0000'0000000000000000.0000
> gmPresent false
> gmIdentity e89a8f.fffe.74f796
>
> 3. Take your local time stamps via vdso (ie clock_gettime).
>
> 4. Use the result of step 2 to figure the global time of the time
> stamps in step 3.
>
> HTH,
> Richard
>
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