Re: [opensuse] Re: chrony and hwclock



On Tue, 2011-07-19 at 10:44 +0200, Per Jessen wrote:
Roger Oberholtzer wrote:

On Tue, 2011-07-19 at 08:14 +0200, Per Jessen wrote:


ntp doesn't care about timezones.

http://en.wikipedia.org/wiki/Network_Time_Protocol

"It provides Coordinated Universal Time (UTC). No information about
time
zones or daylight saving time is transmitted; this information is
outside its scope and must be obtained separately."

OK. That should not be a problem, I guess. The timezone thing is a
per-user setting, not a system setting.

Hmm, I think it's a system thing too - see /etc/localtime

There are two possible usage scenarios:

1. The hardware is in UTC time, and there is a timezone specified that
specifies how to report the local time from the UTC time.

2. The hardware is in localtime, and there is a timezone specified that
specifies how this differs from UTC time.

If ntp is used in a scenario 2, wouldn't it need to be able to set the
clock to local time and not UTC time? How would it do this if it did not
deal with timezones?

Or does the boot.clock always put the clock in UTC time no matter? So,
in my case, the clock would be left alone - it is specified as already
being in UTC time. In scenario 2, the system would change the hardware
clock, based on the timezone, to UTC time. And set it back when the
system is shutdown. Then ntp would indeed only fiddle with UTC time,
which it assumes the hardware clock always to be using. So I am really
confused why restarting ntp moves the time by 2 hours.

Plenty of places where something can go amiss.



Yours sincerely,

Roger Oberholtzer

OPQ Systems / Ramböll RST

Office: Int +46 10-615 60 20
Mobile: Int +46 70-815 1696
roger.oberholtzer@xxxxxxxxxx
________________________________________

Ramböll Sverige AB
Krukmakargatan 21
P.O. Box 17009
SE-104 62 Stockholm, Sweden
www.rambollrst.se


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