Count the number of interrupts that was lost due to interrupt coalescing
and re-inject them back when possible. This fixes time drift problem when
RTC is used as a time source.
Signed-off-by: Gleb Natapov <address@hidden>
---
hw/mc146818rtc.c | 11 +++++++++--
1 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/hw/mc146818rtc.c b/hw/mc146818rtc.c
index 30bb044..505e117 100644
--- a/hw/mc146818rtc.c
+++ b/hw/mc146818rtc.c
@@ -66,6 +66,7 @@ struct RTCState {
int64_t next_periodic_time;
/* second update */
int64_t next_second_time;
+ uint32_t irq_coalesced;
QEMUTimer *second_timer;
QEMUTimer *second_timer2;
};
@@ -101,7 +102,8 @@ static void rtc_periodic_timer(void *opaque)
rtc_timer_update(s, s->next_periodic_time);
s->cmos_data[RTC_REG_C] |= 0xc0;
- qemu_irq_raise(s->irq);
+ if(!qemu_irq_raise(s->irq))
+ s->irq_coalesced++;
}
static void cmos_ioport_write(void *opaque, uint32_t addr, uint32_t data)
@@ -360,7 +362,12 @@ static uint32_t cmos_ioport_read(void *opaque, uint32_t
addr)
case RTC_REG_C:
ret = s->cmos_data[s->cmos_index];
qemu_irq_lower(s->irq);
- s->cmos_data[RTC_REG_C] = 0x00;
+ if(!s->irq_coalesced) {
+ s->cmos_data[RTC_REG_C] = 0x00;
+ } else {
+ if(qemu_irq_raise(s->irq))
+ s->irq_coalesced--;
+ }
break;
default:
ret = s->cmos_data[s->cmos_index];