Invalid time in real time clock

Tim Daneliuk tundra at
Sat Feb 1 15:42:27 UTC 2014

On 02/01/2014 09:07 AM, Christian Weisgerber wrote:
> Over the last few months I started noticing that my FreeBSD/amd64
> desktop box would often come up with a date of Jan 1, 2008 after
> boot.  Presumably the CMOS battery was dying and the motherboard
> picked a date from its year of manufacture.
> So I replaced the CR2032 battery on the motherboard and reapplied
> the BIOS settings that had been lost during the change.  Unfortunately,
> I'm still greeted with
> atrtc0: WARNING: Battery failure indication
> Invalid time in real time clock.
> Check and reset the date immediately!
> Incongruously, the RTC time is actually correct.  Well, off by a
> minute or so.  Clearly the new battery is good.
> I guess this is more a PC question, but how do I get the RTC to
> indicate a valid time again?  The motherboard manual (Asus) is
> rather silent on the whole issue of CMOS battery replacement.

I've seen something similar to this before.  A good solution
is to use ntpdate at boot to initially set the time properly,
and the run ntpd to keep it correct.  Both are enabled
via /etc/rc.conf.

Tim Daneliuk     tundra at
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