Enhanced PTP User Guide (UG1602)

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1.0 English

sfptpd supports some limited use cases with sfptpd running alongside chronyd. For both daemons to co-exist, only one of them can be allowed to discipline the system clock. Unlike NTP, chronyd does not expose an API that can be used to prevent it from controlling the system clock.

The following use cases are possible:

  • From version 3.3.0 onwards, sfptpd has an option to prevent it from disciplining the system clock:
    clock_readonly system

    The system clock is then controlled and adjusted by chronyd, but only read by sfptpd.

    For this to work correctly, you must also set the following option:

    interface system

    See the clock_readonly option in Configuration Options, and the interface option in Instance-specific Configuration Options

  • From version 3.4.0 onwards, sfptpd supports chronyd as NTP server when either sfptpd or chronyd is statically configured not to discipline the system clock. For example to enable the chronyd and PPS use case, launch chronyd with the -x option.

Xilinx recommends that chronyd is disabled and standard NTP installed when NTP functionality is required.