Date: Tue, 20 May 2003 16:16:49 -0400
To: David Balazic <david.balazic@uni-mb.si>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Wrong clock initialization
Message-ID: <20030520201649.GA18678@delft.aura.cs.cmu.edu>
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	linux-kernel@vger.kernel.org
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From: Jan Harkes <jaharkes@cs.cmu.edu>
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On Tue, May 20, 2003 at 07:34:55PM +0200, David Balazic wrote:
> As almost nobody runs their clock in UTC, this means that the system
> is running on wrong time until some userspace tool corrects it.

I thought everybody used the CMOS clock in UTC, which means that the
kernel doesn't have to know anything about nasty little details related
to timezones, daylight savings time and such. Localtime is just a
presentation issue.

> This can lead to situtation when time goes backwards :
> 
> timezone is 2hours east of UTC.
> UTC time : 20:00
> local time : 22:00
> 
> System time between boot and userspace fix : 22:00UTC
> System time after fix : 20:00UTC
> 
> Comments ?

All your disks are typically still mounted readonly and no important
applications are running except for perhaps an fsck /dev/root between
the time the system is booted and the clock is fixed up. So it really
doesn't matter whether your clock is off by a couple of hours for a
couple of seconds (a minute?) during boot.

Jan

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