Date: Sat, 25 Feb 2023 09:02:38 -0800 From: bob prohaska <fbsd@www.zefox.net> To: Mike Karels <mike@karels.net> Cc: freebsd-arm@freebsd.org, freebsd-current@freebsd.org Subject: Re: Timekeeping problem in /usr/src on new RPI aarch64 snapshot Message-ID: <20230225170238.GA11193@www.zefox.net> In-Reply-To: <0BA0C9F7-5F85-4EBF-86BB-428730746592@karels.net> References: <20230224210502.GA8127@www.zefox.net> <1216867532.11893.1677280869319@localhost> <20230225161625.GB8127@www.zefox.net> <0BA0C9F7-5F85-4EBF-86BB-428730746592@karels.net>
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On Sat, Feb 25, 2023 at 10:33:23AM -0600, Mike Karels wrote: > On 25 Feb 2023, at 10:16, bob prohaska wrote: > > > On Sat, Feb 25, 2023 at 12:21:09AM +0100, Ronald Klop wrote: > >> > >> UFS stores the current timestamp in the superblock of the FS on clean > >> shutdown/unmount. On boot it reads the time from the timestamp in the > >> superblock of the root FS. Of coarse this timestamp is behind for the > >> duration that the machine was off or rebooting so you need to adjust that > >> using ntp. For ZFS root you can use the fakertc port to do something > >> similar. > >> > >> > > Mark Millard points out: > > /etc/localtime Current zoneinfo file, see tzsetup(8) and zic(8). > > > > /etc/wall_cmos_clock Empty file. Its presence indicates that the > > machine's CMOS clock is set to local time, while > > its absence indicates a UTC CMOS clock. > > > > Since there is no /etc/wall_cmos_clock on the newly-installed filesystem > > it appears the superblock timestamp is then interpreted as UTC when a Pi > > boots, using whatever happens to be set in /etc/localtime. My confusion > > is reduced somewhat. On first boot, what is the state of /etc/localtime? > > > > I've neglected to run tzsetup immediately on many previous installations > > and not noticed any complaints about mis-set clocks in buildworld. Is this > > new behavior? > > /etc/localtime is used in formatting dates (e.g. for ls), but is not > involved in storage of timestamps. Timestamps on files, system time, etc, > are all in UTC. So the system should act normally if there is no > /etc/localtime, and after one is added. Does formatting include calculating offsets from UTC for display? On at least a couple of installs I've observed date reporting UTC time. After running tzsetup, set to PST, date then reported the same numerical time with a PST time zone. This happened very early in an installation lifecycle and seemed to just "go away" after a few reboots, though I never paid close attention since it caused no complaints. Thanks for replying! bob prohaska
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