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Re: hwclock on a PowerMac 9500 and summertime

On   1 Apr, this message from Boris Bezlaj echoed through cyberspace:
> On Tue, Apr 01, 2003 at 08:25:39PM +0200, David Ulrich wrote:
>> I put it on summertime and add a ntp server (ntp, ntp-simple and 
>> ntpupdate). So the clock is always on time.
>> My debian is always on time now:

>> But I can fix my hardware clock on summertime:
>> dulrich# hwclock --show
>> Tue Apr  1 19:15:32 2003  -0.984699 seconds
>> I try:
>> hwclock --systohc, hwclock stop/start, hwclock force-reload
>> The hardware clock get the summertime:
>> hwclock --systohc
>> daisy:/home/dulrich# hwclock --show
>> Tue Apr  1 20:15:21 2003  -0.454536 seconds
>> but some minutes later:
>> dulrich# hwclock --show
>> Tue Apr  1 19:18:09 2003  -0.510788 seconds


> IMHO, the best practice is to keep hw clock coordinated to
> UTC(Greenwich), and use the right timezone..that way you never need to
> worry about summer time shift 8)

Which is the best solution if you never run MacOS.

However, there are two things to note here:

- MacOS also keeps a DST flag in nvram, which will be honoured by Linux
  upon boot. So it can happen that your time is an hour off until you
  run ntpdate in the startup scripts.

- You may have some script running which periodically updates the RTC
  with the current (kernel) time. Have a look at the /etc/cron.d
  directory and the other /etc/cron* files. It _might_ also be the
  kernel together with the RTC driver who's updating the clock, not

- The above-mentioned auto-update will likely fail if you have the wrong
  UTC/non-UTC setting in /etc/default/rcS.

Hope this helps


Michel Lanners                 |  " Read Philosophy.  Study Art.
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