Post #2958992
2026-03-26 15:54 UTC
I tried having Chrony use SHM0 for GPS, and reading the /dev/pps0 device directly for PPS... which would work fine for several hours, then PPS data would just randomly stop. Weird. Meanwhile, GPSd still has a running PPS feed.
What finally worked for me was getting GPS via SHM0 from GPSd, and PPS via socket from GPSd. That has been stable for a couple days now. But that doesn't work if I "lock" PPS to GPS. Weird.
5/x
Replies (1)
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@rune@social.intothecloud.net 2026-03-26 15:55
The config for sockets is also weird. You need to tell Chrony that its reference clock is /run/chrony..sock (for me, /run/chrony.pps0.sock), a file that does not exist, which Chrony creates. GPSd, when it starts, without any config, looks for that socket, and if it exists, communicates with it (connects as root, then sheds privileges). 6/7