On Sat, 2011-07-16 at 10:35 +0200, Per Jessen wrote:
Per Jessen wrote:
If you need a higher degree of accuracy without a more accurate external time source, you have to improve the local time source - temperature controlled xtal oscillator etc.
btw, this is perfectly feasible. You can build/buy very stable TXCOs that will supply a very good PPS signal. Companies such www.rakon.com make very tiny devices with very good accuracies.
In our case, we are using high end GPS receivers with a PPS signal on the serial port. This causes a hardware interrupt when a time update is available. This is a rather accurate event when used in conjunction with a time setting daemon that can use the data and associated PPS signal from a GPS. In newer kernels, there is a PPS driver that has finally abstracted all these possible PPS signals into a single interface (/dev/pps). We currently do some of this time synchronizing in our own application. I do not want to do that anymore. It is because I am investigating what the caveats are when this is done at the system level when a system is not connected to the internet (an assumption that is unfortunately becoming more and more common) that the original question came up. And that question (still not answered) is: is there any unexpected side effect of not running the hwclock shutdown script? In my case, chrony wants to maintain the hardware clock between boots. It is understood that the jury is out as to whether chrony is a useful solution. But that was not the question. Does the hwclock shutdown script maintain any information used by any systems other than hwclock itself? Yours sincerely, Roger Oberholtzer OPQ Systems / Ramböll RST Office: Int +46 10-615 60 20 Mobile: Int +46 70-815 1696 roger.oberholtzer@ramboll.se ________________________________________ Ramböll Sverige AB Krukmakargatan 21 P.O. Box 17009 SE-104 62 Stockholm, Sweden www.rambollrst.se -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org