Hello Darryl, On Tuesday, August 26, 2008 at 22:24:37 +0000, Darryl Miles wrote:
> I'm not sure I agree that hwclock/drift file is even good for managing > the hardware RTC. While the machine is switched on we have NTP, while > the machine is switched off the internal/component temperature is > vastly different so any drift estimation maintained over time whilst > powered up might not be in the right ballpark Of course: hwclock needs the switched-off-during-night RTC drift rate in its /etc/adjtime file, in order to initialise at best the system clock at startup next morning, before NTP takes control. > you do maintain different drift data whilst powered up and powered > down don't you ? Outside of some specific cases (like 24/7 servers), generally hwclock doesn't really care about the drift rate of the RTC during power up. Maintaining 2 rates is of course possible, but delicate. In many cases there is only one important drift rate: the power-down rate. One basic method to get and use the power-down RTC drift rate is to call "hwclock --systohc --nodrift" during shutdown, with --nodrift to prevent an importune recalculation of the rate. Then after startup, as soon as the system clock is tightly synced, call "hwclock --systohc" to evaluate the RTC drift since the last shutdown. However this method cannot possibly work with the eleven-minutes mode. Serge. -- Serge point Bets arobase laposte point net _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
