timemaster source selection does not respect PTP priority1 values in multi-GM configurations

[ni8towl]

Summary

When multiple PTP sources are configured in timemaster.conf, chronyd selects between them based on observed clock quality rather than the priority1 values configured on the GM clocks.

Expected behaviour

Engineers configuring priority1 to designate a primary and backup GM clock have a reasonable expectation that the primary (lower priority1 value) will be preferred by the host when both sources are available and healthy.

Observed behaviour

With two GM clocks configured — one with priority1=127, one with priority1=128 — chronyd selected the priority1=128 clock based on observed offset quality, ignoring the priority1 designation entirely.

Environment

• Platform: SEAPATH Debian 6.1 PREEMPT_RT
• PTP stack: timemaster with linuxptp ptp4l 3.1.1
• Configuration: two separate [ptp_domain 0] interfaces, each connected to a Relyum GM clock
• Both clocks: GPS-locked, clock class 6, domain 0

Proposed improvement

The SEAPATH Ansible timemaster role could configure chronyd source weighting to reflect the GM priority1 values — for example by setting a lower delay value for the domain section associated with the primary GM. This would allow the engineer's priority1 configuration to influence source selection without requiring changes to the linuxptp or chronyd software themselves.

References

• timemaster(8) man page — delay option in [ptp_domain] section
• chronyd source selection documentation