On 11/08/2011 07:18 PM, Max Filippov wrote:
hpet_timer timer callback rearms itself based on difference between
current HPET tick counter and comparator value. Difference calculated by
the hpet_calculate_diff function is limited to non-negative values.
cur_tick is calculated via hpet_get_ticks that uses qemu_get_clock_ns(vm_clock).
With -icount enabled vm_clock doesn't advance during qemu_run_timers
loop thus once difference is zero, qemu_run_timers loops forever
handling hpet_timer.
Limit hpet_calculate_diff results to positive only values to avoid that
infinite loop.
This fixes the following qemu-system-x86_64 hang when it reaches
timer_irq_works() in the linux bootup:
[ 0.000000] Fast TSC calibration using PIT
[ 0.000000] Detected 1000.054 MHz processor.
[ 0.000031] Calibrating delay loop (skipped), value calculated using timer
frequency.. 2000.10 BogoMIPS (lpj=10000540)
[ 0.000404] pid_max: default: 32768 minimum: 301
[ 0.001138] Mount-cache hash table entries: 256
[ 0.003883] Initializing cgroup subsys ns
[ 0.004035] Initializing cgroup subsys cpuacct
[ 0.004280] Initializing cgroup subsys freezer
[ 0.004790] Performance Events: AMD PMU driver.
[ 0.004985] ... version: 0
[ 0.005134] ... bit width: 48
[ 0.005285] ... generic registers: 4
[ 0.005437] ... value mask: 0000ffffffffffff
[ 0.005625] ... max period: 00007fffffffffff
[ 0.005807] ... fixed-purpose events: 0
[ 0.005957] ... event mask: 000000000000000f
[ 0.006275] SMP alternatives: switching to UP code
Signed-off-by: Max Filippov<jcmvb...@gmail.com>
Applied. Thanks.
Regards,
Anthony Liguori
---
hw/hpet.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/hw/hpet.c b/hw/hpet.c
index 12bd64d..6e6ea52 100644
--- a/hw/hpet.c
+++ b/hw/hpet.c
@@ -157,14 +157,14 @@ static inline uint64_t hpet_calculate_diff(HPETTimer *t,
uint64_t current)
cmp = (uint32_t)t->cmp;
diff = cmp - (uint32_t)current;
- diff = (int32_t)diff> 0 ? diff : (uint32_t)0;
+ diff = (int32_t)diff> 0 ? diff : (uint32_t)1;
return (uint64_t)diff;
} else {
uint64_t diff, cmp;
cmp = t->cmp;
diff = cmp - current;
- diff = (int64_t)diff> 0 ? diff : (uint64_t)0;
+ diff = (int64_t)diff> 0 ? diff : (uint64_t)1;
return diff;
}
}
