On Wed, Jul 20, 2022 at 03:12:39PM +0200, Jakub Raczyński wrote: > phc2sys[2031.823]: lan1 sys offset 4870 s0 freq +0 delay 1875 > phc2sys[2032.824]: lan1 sys offset 4915 s0 freq +0 delay 1875 > phc2sys[2033.824]: lan1 sys offset 5011 s0 freq +0 delay 1750 > phc2sys[2034.825]: port 360712.fffe.52efd6-1 changed state > phc2sys[2034.826]: reconfiguring after port state change > phc2sys[2034.828]: master clock not ready, waiting... > phc2sys[2035.828]: port 360712.fffe.52efd6-1 changed state > phc2sys[2035.830]: reconfiguring after port state change > phc2sys[2035.831]: selecting CLOCK_REALTIME for synchronization > phc2sys[2035.832]: selecting lan1 as the master clock > phc2sys[2035.833]: CLOCK_REALTIME phc offset -5136 s0 freq +0 delay > 1875 > phc2sys[2036.834]: CLOCK_REALTIME phc offset -4435 s0 freq +0 delay > 1875 > > So, as mentioned "That is not expected to work" but kinda did or seemed like > it. Would need more research and debugging what is actually happening inside > both servos.
There is only one SHM segment and it's used by ntpd for synchronization of the system clock. When phc2sys reverses the direction, the offset will flip the sign, intending to synchronize the PHC to the system clock, but ntpd will still be using the data it receives to synchronize the system clock, which will cause a positive feedback loop and the clock will be steered away, stepped, or ntpd will give up depending on its configuration. -- Miroslav Lichvar _______________________________________________ Linuxptp-users mailing list Linuxptp-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-users
