Re: [Qemu-devel] BUG: RTC issue when Windows guest is idle

[Alex Bligh]

On 30 Oct 2013, at 01:29, Xiexiangyou wrote:

> RTC timer may stop after live migration if you set the rtc_clock = 
> host_clock. Because the different hosts have different system time.
> Rtc is waiting for the next_periodic_time after migrating, it may wait more 
> longer. During the time, VM will lose one tick with great possibility,

Surely at worst this should wait until the destination RTC catches up?

> and the RTC periodic timer interrupt is blocked by "ioapic->irr==1" in KVM 
> module.

Don't understand the significance of that. Why would the ioapic register be 
different after migration than before?

> To solve the problem, you can try "rtc_clock = vm_clock"(HPET is ok because 
> it using vm_clock). Like this:
>  <clock offset='utc'>
>    <timer name='rtc' tickpolicy='catchup' track='guest'/>
>    <timer name='hpet' present='no'/>
>  </clock>
> 
> I hope it will help you.

-- 
Alex Bligh