You can skip the ntp/systemd-timesyncd/fake-hwclock stuff if you add a RTC/coin ...

		jasongill on March 30, 2024 \| parent \| context \| favorite \| on: Running a Raspberry Pi with a read-only root files... You can skip the ntp/systemd-timesyncd/fake-hwclock stuff if you add a RTC/coin battery to the device. The Raspberry Pi 5 has built-in RTC with support for an official battery which costs about five bucks and works well for this. Older devices have aftermarket RTC's with battery backups as well.

Theres also a kernel option to sync PPS on a gpio from a gps clock