Re: [chrony-users] RTC Trimming Issues

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Ed W <lists@xxxxxxxxxxxxxx> wrote on 11/01/2012 18:47:54:
> > Hi, I see *exactly* your problems with my PCEngines Alix 2D3 boards.
> > About 30% of boards seem to boot and the RTC driver seems borked,
> > therefore you can't set the clock with chrony, but a *warm* reboot
> > and the RTC starts correctly next time and hence you can set it, and
> > after that it all seems to work...
> That does seem similar, but I'm not sure they're really the same.  
> Our problem boards -- again, most of the same model do work just
> fine -- seem to grumble or show problems in setting the RTC as if
> the operation has failed, but then upon a reboot, all suddenly looks
> good.  I don't have a clear picture yet on warm vs. cold booting.  
> When I reboot them for my own testing, it's always warm because
> they're remote and that's all I've got.  However, these boards do
> routinely get powered down (without any formal shutdown process)
> because they're attached to the power buss of production machinery,
> which gets powered off as needed.

> Yes, mine have (working) batteries, so they only need setting once
> and then stay corrected despite power loss. I have a couple of
> hundred boards and I don't measure the exact number, but say 1/4 to
> 1/3 exhibit this effect before first initialisation, until they have
> a warm reboot (they remain fine after initialisation)
> - I haven't seen any exhibit this after the clock is set once

This is where I think our situations differ.  I do have some that go wonky **again** even after I've set the clock.  Maybe we're setting the clock differently.  What method specifically do you use? The hwclock command, the BIOS, something else?

Or maybe, my situation is just like yours but in this same batch, I have a few boards that genuinely have bad batteries.

> - Its at least partly kernel related because literally there can be
> no /dev/rtc device and inability to set the hwclock
> I guess no one would likely spot this if it only happens
> occasionally on uninitialised RTC? Most people either have a battery
> or know that they don't have a battery and hence don't set the RTC...
> Good luck chasing it down
> Ed W

John Florian

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