Kalle Pokki wrote:
On Tue, May 4, 2010 at 16:03, Rini van Zetten <[email protected]> wrote:
I'm trying to setup an embedded system with ntpd and a gps device as reference
clock.
Everyhing went fine when the clock is not too far away when i start ntpd.
But when the clock offset is big (1-1-1970 for example), the ntpd refuses to
use the gps reference clock.
Using the "-g" option does not make any difference.
I'm using ntpd 4.2.6p1
Does anybody know how to setup this ? (i have no lan connection, so an initial
ntpdate is no option)
The system clock needs to be within 4 hours of the correct time for
NTP to synchronize to a reference clock. It seems this is not
considered a bug by the NTP developers although the behaviour is a
major blocker to use NTP with a reference clock in embedded not
constantly supervised environments. If the RTC time is lost, there is
no way for the system to synchronize to a reference clock anymore.
See https://bugs.ntp.org/417 for a discussion. There have been patches
to overcome this, but they have not been accepted.
The most annoying thing is that there are no warning messages
anywhere. The time from the reference clock is just discarded
silently.
Yes, this is exactly right. We worked around this problem in our system
by grabbing the time from the refclock, setting system time with the
refclock time, quick sync NTP, and then finally start the NTP daemon.
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