[chrony-users] New refclock implementation for macOS using gPTP

[ Thread Index | Date Index | More chrony.tuxfamily.org/chrony-users Archives ]

To: chrony-users@xxxxxxxxxxxxxxxxxxxx
Subject: [chrony-users] New refclock implementation for macOS using gPTP
From: James Clark <jjc@xxxxxxxxxx>
Date: Fri, 4 Sep 2026 11:50:46 +0700
Arc-authentication-results: i=1; mx.google.com; arc=none
Arc-message-signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20260327; h=to:subject:message-id:date:from:mime-version:dkim-signature; bh=uucPeo+/p7T+nzyMXXJjTtjnb32TbVvzF2bckTH2PSk=; fh=GqPaxfLkQXkHroAhfrRrmM2mU5H80lQ+JlDifPvguJc=; b=IOYb97j76UjVf0b1Vvo44A4Ufwx6nFoZ6DSv5s512WS2ebMcFGP9ipwMP9sTZUDcVj EIkUvffnPqBCo3EAglia4PfVXJWeMCQZd+52u8zbYbyKeTfTfTwK70EhqFgWxxblo3sI Yv10QaW60dPwTA+8VDVDQfsNx1vu2PuyHw9ZV0cJUqQkGVDVvZ2+IgqXu7Z9XsVb8ndU UAXnp+ZK1qFTzHiFZhg8D0lQfA1uiVi2LnIeOK2d8HZjG30k4netNV23HmsYUmtEnIdo 1Lmes7pGIRi0gFagGLK++7YxoOfwrGqMKUaIeDthMP46xWb45naISS+qsQOdpfw1E3od DUVg==; darn=chrony.tuxfamily.org
Arc-seal: i=1; a=rsa-sha256; t=1788497457; cv=none; d=google.com; s=arc-20260327; b=eFVBxQfy6DRdyxH3WO90jCRkA5Y5BKQEBmXCZCk8DbfvHaBuruMQB+kggdUtI22/il 9uhoxYXdCJiilXBlO6NS3Jt3uoHVLL5PhIim+cIUpwCw4kaEQqF7urul2f3l7Mpug8DQ ZWIzVzsdyhDw9XcWDNfuXWcBXz0uhZTrLGv7YOSLtyUSW2KJ+pNoPWrXIreWnDmg2EYs 38rb83kHsm8JSbUeScO7QMF6wQmWuiTcNg5XSnJlLZ2CquHDCfV/9gwjXGhobLKbwMGD q/zGK0SA5CDjGfKy7H/V6y8g1EABjc8lK27lxIlHiNTSN0dDDJ6VLJNOfSi8PMNozuc1 pxxQ==
Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=jclark-com.20251104.gappssmtp.com; s=20251104; t=1788497457; x=1789102257; darn=chrony.tuxfamily.org; h=content-type:to:subject:message-id:date:from:mime-version:from:to :cc:subject:date:message-id:reply-to:content-type; bh=uucPeo+/p7T+nzyMXXJjTtjnb32TbVvzF2bckTH2PSk=; b=p6vqYjViwmS8qWV52SS4euKziQR8/KQTwf86FcsA+CukkVnUSqYCn62ALLc1CNOjqS 4V7wP1xcUa738tofBSVNYlRjkdKiQAEhjrBctiH09uBbgjTzLvxAi4ZEqsdX9FQ7suQb odlJyM+lnFYLsI4OqjipNaMw9o/GPDVQKs49PyrKclRrmgcnwAJocIOEHYUMP83WgF/J XNzm56eJyMh0kSPjCmil4TROlOX7BI8q2GSgTjZTOsZQW5Q0iNNS5ZIjEVHw+G8dmAAZ 6ROEm0HEB2XhTMYISFSRbYxrT/YcpIffBbKtwkyhr//X9e8qnSyVLiaAY/TZGN7y5LJ3 a6Xg==

It turns out that macOS has an undocumented, private TimeSync framework that exposes the gPTP implementation that underlies AVB. I have created a refclock implementation that can feed samples from this into chrony. Claude Fable did most of the work. ChatGPT 5.6 Pro helped devise chrony settings to make this work well; this was challenging because the oscillator on the Mac Mini seems pretty bad. My chrony instance is showing an RMS of under 0.5 µs now.

Repo is here: https://github.com/jclark/mac-gptp

James

Messages sorted by: [ date | thread ]
Prev by Date: Re: [chrony-users] Offsets for non tested servers
Previous by thread: Re: [chrony-users] Offsets for non tested servers

Mail converted by MHonArc 2.6.19+

http://listengine.tuxfamily.org/