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Fix non-TSC guest clocksource lockup

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lguest uses a host-supplied wallclock-based clocksource when the TSC
is not reliable.  As this is already in nanoseconds, I naively used a
multiplier of 1 and a shift of 0.

But update_wall_time() in its infinite wisdom decides to adjust the
clock a little (where does it think it's getting a more accurate time
from?)

It will happily tweak the multiplier... to 0, then -1.

So the "fix" is to use a shift of 22 like everyone else, and a
multiplier of 1 << 22.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Rusty Russell 2007-08-09 20:52:35 +10:00 committed by Linus Torvalds
parent 88ffc35059
commit 37250097e1
1 changed files with 2 additions and 2 deletions
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4
drivers/lguest/lguest.c
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@ -687,7 +687,8 @@ static struct clocksource lguest_clock = {
.rating = 400,
.read = lguest_clock_read,
.mask = CLOCKSOURCE_MASK(64),
.mult = 1,
.mult = 1 << 22,
.shift = 22,
};
/* The "scheduler clock" is just our real clock, adjusted to start at zero */
@ -770,7 +771,6 @@ static void lguest_time_init(void)
* way, the "rating" is initialized so high that it's always chosen
* over any other clocksource. */
if (lguest_data.tsc_khz) {
lguest_clock.shift = 22;
lguest_clock.mult = clocksource_khz2mult(lguest_data.tsc_khz,
lguest_clock.shift);
lguest_clock.flags = CLOCK_SOURCE_IS_CONTINUOUS;