Date: Tue, 26 Nov 2019 15:43:42 -0700 From: Ian Lepore <ian@freebsd.org> To: Bakul Shah <bakul@bitblocks.com>, James Shuriff <james@opentech.cc> Cc: "freebsd-arm@freebsd.org" <freebsd-arm@freebsd.org> Subject: Re: rpi3 clock drift Message-ID: <724aadb502353b0a2156d98f613cfa2bf2e6dd4c.camel@freebsd.org> In-Reply-To: <20191126222952.6BCFA156E80B@mail.bitblocks.com> References: <MWHPR06MB3134CD05551D36CC3B45D368AA450@MWHPR06MB3134.namprd06.prod.outlook.com> <20191126222952.6BCFA156E80B@mail.bitblocks.com>
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On Tue, 2019-11-26 at 14:29 -0800, Bakul Shah wrote: > On Tue, 26 Nov 2019 22:03:30 +0000 James Shuriff <james@opentech.cc> wrote: > > My Raspberry Pi 3 Model B is having some serious clock drift issues. Ntpd doe > > sn't function even with ntpd_sync_on_start, which calls ntpd with -g and allo > > ws the initial adjustment to exceed the panic threshold. This doesn't help 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 awar > > e of the clock. > > > > There is a file in the Raspberry Pi firmware repo called i2c-rtc.dtbo and it > > contains defs for clocks like DS1307 so I am assuming I can add this to confi > > g.txt, build U-Boot with CONFIG_RTC_DS1307 (or whatever model), and build 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? > > Is the clock really drifting or is this due the initial time > being waaay off from the current time due to a lack of RTC? If > the latter do the initial time setup using ntpdate. Add > > ntpdate_enable="YES" > > to /etc/rc.conf. > > If you can already use ntpd, there is not much point in using a local > rtc. > Using ntpd_sync_on_start=YES is effectively the same as using ntpdate_enable=YES... it gives ntpd permission to step the clock any amount, one time at startup. -- Ian
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