I am using an X440-8t (EXOS 220.127.116.11) with the AVB package to connect together 5 AVB endpoints. I have also configured the X440 as an NTP client, deriving its NTP clock from a PC that is synchronised to a local GPS receiver. The gPTP clock maintained by the X440 appears to have a significant offset from the NTP clock. The only way of reducing this offset appears to be to power-cycle the switch - doing this appears to reduce the gPTP clock offset, but it is still not zero.
From this, I infer that the gPTP clock and the NTP clock are maintained entirely separately within the X440, and that the only connection between them is that the former is initialized from the latter (not especially precisely) when the switch is powered up. Is this correct?
Does the NTP function in the X440 generate a "drift" file (as it does in Linux implementations) to correct for rate errors in the underlying clock? And, if so, is this drift file also used to correct the rate of the gPTP clock?
Is there a more precise way to set the gPTP clock from the NTP clock in the X440 (preferably without adding additional hardware to the network).