Commit cfd28f66 authored May 12, 2008 by Jeff Dike Committed by Linus Torvalds May 13, 2008

uml: fix bad NTP interaction with clock



UML's supposed nanosecond clock interacts badly with NTP when NTP
decides that the clock has drifted ahead and needs to be slowed down.
Slowing down the clock is done by decrementing the cycle-to-nanosecond
multiplier, which is 1.  Decrementing that gives you 0 and time is
stopped.

This is fixed by switching to a microsecond clock, with a multiplier
of 1000.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 309e96cd

arch/um/kernel/time.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -75,7 +75,7 @@ static irqreturn_t um_timer(int irq, void *dev)

		static cycle_t itimer_read(void)
		{
		return os_nsecs();
		return os_nsecs() / 1000;
		}

		static struct clocksource itimer_clocksource = {
		@@ -83,7 +83,7 @@ static struct clocksource itimer_clocksource = {
		.rating = 300,
		.read = itimer_read,
		.mask = CLOCKSOURCE_MASK(64),
		.mult = 1,
		.mult = 1000,
		.shift = 0,
		.flags = CLOCK_SOURCE_IS_CONTINUOUS,
		};

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