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Date:      Tue, 26 Nov 2019 22:03:30 +0000
From:      James Shuriff <james@opentech.cc>
To:        "freebsd-arm@freebsd.org" <freebsd-arm@freebsd.org>
Subject:   rpi3 clock drift
Message-ID:  <MWHPR06MB3134CD05551D36CC3B45D368AA450@MWHPR06MB3134.namprd06.prod.outlook.com>

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My Raspberry Pi 3 Model B is having some serious clock drift issues. Ntpd d=
oesn't function even with ntpd_sync_on_start, which calls ntpd with -g and =
allows the initial adjustment to exceed the panic threshold. This doesn't h=
elp me much because the system will continue to drift very quickly and that=
 option only helps for the initial adjustment.

I was thinking of ordering an I2C RTC but I'm unsure how to make FreeBSD aw=
are of the clock.

There is a file in the Raspberry Pi firmware repo called i2c-rtc.dtbo and i=
t contains defs for clocks like DS1307 so I am assuming I can add this to c=
onfig.txt, build U-Boot with CONFIG_RTC_DS1307 (or whatever model), and bui=
ld the kernel with device support for the clock but I'm not completely sure=
 if I'm going about this the right way. Beyond just getting FreeBSD to see =
the clock I'm unsure how to tell FreeBSD to use it. Any advice?

Thanks,

- James Shuriff

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