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    SubjectRe: PROBLEM: Linux updates RTC secretly when clock synchronizes
    Hi!

    > PROBLEM: Linux updates RTC secretly when clock synchronizes.
    >
    > Please CC replies etc to Ian Maclaine-cross <iml@debian.org>.
    >
    > When /usr/sbin/ntpd synchronizes the Linux kernel (or system) clock
    > using the Network Time Protocol the kernel time is accurate to a few
    > milliseconds. Linux then sets the Real Time (or Hardware or CMOS)
    > Clock to this time at approximately 11 minute intervals. Typical RTCs
    > drift less than 10 s/day so rebooting causes only millisecond errors.
    >
    > Linux currently does not record the 11 minute updates to a log file.
    > Clock programs (like hwclock) cannot correct RTC drift at boot without
    > knowing when the RTC was last set. If NTP service is available after a
    > long shutdown, ntpd may step the time. Worse after a longer shutdown
    > ntpd may drop out or even synchronize to the wrong time zone. The
    > workarounds are clumsy.
    >
    > Please find following my small patch for linux/arch/i386/kernel/time.c
    > which adds a KERN_NOTICE of each 11 minute update to the RTC. This is
    > just for i386 machines at present. A script can search the logs for
    > the last set time of the RTC and update /etc/adjtime. Hwclock can
    > then correct the RTC for drift and set the kernel clock.

    That seems as very wrong solution.

    What about just making kernel only _read_ system clock, and never set it?
    That looks way cleaner to me.

    Pavel
    --
    Philips Velo 1: 1"x4"x8", 300gram, 60, 12MB, 40bogomips, linux, mutt,
    details at http://atrey.karlin.mff.cuni.cz/~pavel/velo/index.html.

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