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Re: Power loss and system time when not having a battery backed RTC

To: Markus Gothe <markus.gothe@27m.se>
Subject: Re: Power loss and system time when not having a battery backed RTC
From: Attila Kinali <attila@kinali.ch>
Date: Wed, 28 Mar 2007 17:22:16 +0200
Cc: linux-mips@linux-mips.org
In-reply-to: <460A8014.1020100@27m.se>
Organization: NERV
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20070328163914.b7187fcb.attila@kinali.ch> <460A8014.1020100@27m.se>
Sender: linux-mips-bounce@linux-mips.org
N'abend,

On Wed, 28 Mar 2007 16:47:48 +0200
Markus Gothe <markus.gothe@27m.se> wrote:

> Attila Kinali wrote:
> > How do you handle this issue with the back jumps, if you cannot
> > stick in a batter backed RTC?

> Be creative or use the battery, you could for example set a timestamp
> in a file at shutdown and use it to set the date on power up, alas
> this would be incorrect, so go for the battery.

We cannot stick in a battery as there is not enough space
in the housing of the print (to be exact, we don't have enough
height).

I already thought about storing the last known time somewhere
in the flash. But unfortunately the device can be unplugged
suddenly w/o correct shutdown (actualy this is the normal case).
The only way around this i could came up with was to periodically
store the current time. But this is then a trade off between
jump back period length and how long the flash will last the
continous writes, with no sweet spot that looks good.


Tack och ha det sa bra

                                Attila Kinali
-- 
Praised are the Fountains of Shelieth, the silver harp of the waters,
But blest in my name forever this stream that stanched my thirst!
                         -- Deed of Morred

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