[ntp:questions] Linux NTP Kernel unsync flag remains long after NTP&Kernel have PPL sync

Serge Bets serge.bets at NOSPAM.laposte.invalid
Tue Sep 2 15:32:51 UTC 2008

Hello Bill,

 On Saturday, August 30, 2008 at 16:54:47 +0000, Unruh wrote:

> when hpet is enabled, all the interrupts from the rtc are hjacked and
> never delivered to the system as rtc interrupts.

Exact. The nice dreams above about the mythical RTC microsecond are
totally annihilated by the HPET problem. Solutions today are only nohpet
or --directisa. However it appears that, following your bug report,
David Brownell is now exploring a new workaround for future kernels.
IIUC he managed to convince ACPI to intercept RTC interrupts and to
forward them to the CPU. I could not test the patch, and know nothing
about ACPI. But this looks quite promising.

> And yes, Mandriva uses the util-linux version

So do the current and the (now frozen) future Debians, and so does
Ubuntu. They also call hwclock --hctosys *twice* at startup (¿!¡?).
They evaluate the drift rate from shutdown to shutdown, thus including
uptime. And they don't correct drift at all.

At the morning startup, those distros would give me an initial offset of
maybe 5 plain seconds, instead of the 5 milliseconds or better I get
routinely from hwclock 2.33

> Why does Brian not get his version back into util-linux?

To me, hwclock seems to be much better standalone than in a collection
of unrelated utilities. Active development vs. careless stagnation.

Serge point Bets arobase laposte point net

More information about the questions mailing list