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Date: Wed, 12 Dec 2012 19:36:31 -0200
From: Marcelo Tosatti <mtosatti@redhat.com>
Message-ID: <20121212213631.GA27694@amt.cnet>
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Subject: [Qemu-devel] [PATCH] RTC: enable lost_tick_policy=slew as default
	(v2)
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To: qemu-devel@nongnu.org
Cc: Jan Kiszka <jan.kiszka@siemens.com>, Paolo Bonzini <pbonzini@redhat.com>


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>

v2: do not change default for older machines types (Paolo Bonzini)

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(),
 };
 
diff --git a/hw/pc_piix.c b/hw/pc_piix.c
index 19e342a..475bb4c 100644
--- a/hw/pc_piix.c
+++ b/hw/pc_piix.c
@@ -295,6 +295,10 @@ static QEMUMachine pc_machine_v1_4 = {
             .driver   = "usb-tablet",\
             .property = "usb_version",\
             .value    = stringify(1),\
+        },{\
+            .driver   = "mc146818rtc",\
+            .property = "lost_tick_policy",\
+            .value    = "discard",\
         }
 
 static QEMUMachine pc_machine_v1_3 = {