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* [Qemu-devel] [PATCH] RTC: enable lost_tick_policy=slew as default
@ 2012-12-11 21:49 Marcelo Tosatti
  2012-12-12  8:43 ` Paolo Bonzini
  0 siblings, 1 reply; 2+ messages in thread
From: Marcelo Tosatti @ 2012-12-11 21:49 UTC (permalink / raw)
  To: Jan Kiszka, qemu-devel


RTC interrupt reinjection has no known negative effect. Lack of 
RTC interrupt reinjection, though, has negative effects: time drift
for Windows guests which use it as a timer source. 

Based on that, enable lost_tick_policy=slew option as default.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

diff --git a/hw/mc146818rtc.c b/hw/mc146818rtc.c
index c79fca7..c9e007d 100644
--- a/hw/mc146818rtc.c
+++ b/hw/mc146818rtc.c
@@ -884,7 +884,7 @@ ISADevice *rtc_init(ISABus *bus, int base_year, qemu_irq intercept_irq)
 static Property mc146818rtc_properties[] = {
     DEFINE_PROP_INT32("base_year", RTCState, base_year, 1980),
     DEFINE_PROP_LOSTTICKPOLICY("lost_tick_policy", RTCState,
-                               lost_tick_policy, LOST_TICK_DISCARD),
+                               lost_tick_policy, LOST_TICK_SLEW),
     DEFINE_PROP_END_OF_LIST(),
 };
 

^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [Qemu-devel] [PATCH] RTC: enable lost_tick_policy=slew as default
  2012-12-11 21:49 [Qemu-devel] [PATCH] RTC: enable lost_tick_policy=slew as default Marcelo Tosatti
@ 2012-12-12  8:43 ` Paolo Bonzini
  0 siblings, 0 replies; 2+ messages in thread
From: Paolo Bonzini @ 2012-12-12  8:43 UTC (permalink / raw)
  To: Marcelo Tosatti; +Cc: Jan Kiszka, qemu-devel

Il 11/12/2012 22:49, Marcelo Tosatti ha scritto:
> 
> RTC interrupt reinjection has no known negative effect. Lack of 
> RTC interrupt reinjection, though, has negative effects: time drift
> for Windows guests which use it as a timer source. 
> 
> Based on that, enable lost_tick_policy=slew option as default.
> 
> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
> 
> diff --git a/hw/mc146818rtc.c b/hw/mc146818rtc.c
> index c79fca7..c9e007d 100644
> --- a/hw/mc146818rtc.c
> +++ b/hw/mc146818rtc.c
> @@ -884,7 +884,7 @@ ISADevice *rtc_init(ISABus *bus, int base_year, qemu_irq intercept_irq)
>  static Property mc146818rtc_properties[] = {
>      DEFINE_PROP_INT32("base_year", RTCState, base_year, 1980),
>      DEFINE_PROP_LOSTTICKPOLICY("lost_tick_policy", RTCState,
> -                               lost_tick_policy, LOST_TICK_DISCARD),
> +                               lost_tick_policy, LOST_TICK_SLEW),
>      DEFINE_PROP_END_OF_LIST(),
>  };
>  
> 
> 
> 

This needs versioning for old machine types, though.

Paolo

^ permalink raw reply	[flat|nested] 2+ messages in thread

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2012-12-11 21:49 [Qemu-devel] [PATCH] RTC: enable lost_tick_policy=slew as default Marcelo Tosatti
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