On Tue, 15 Nov 2011, Anthony Liguori wrote:
> On 11/15/2011 08:51 AM, stefano.stabellini@xxxxxxxxxxxxx wrote:
> > From: Stefano Stabellini<stefano.stabellini@xxxxxxxxxxxxx>
> >
> > Xen doesn't need full RTC emulation in Qemu because the RTC is already
> > emulated by the hypervisor. In particular we want to avoid the timers
> > initialization so that Qemu doesn't need to wake up needlessly.
> >
> > Signed-off-by: Stefano Stabellini<stefano.stabellini@xxxxxxxxxxxxx>
>
> Yuck. There's got to be a better way to do this.
Yeah, it is pretty ugly, I was hoping in some good suggestions to
improve this patch :)
> I think it would be better to name timers and then in Xen specific machine
> code,
> disable the RTC timers.
Good idea!
I was thinking that I could implement an rtc_stop function in
mc146818rtc.c that stops and frees the timers.
Now the problem is that from xen-all.c I cannot easily find the
ISADevice instance to pass to rtc_stop. Do you think it would be
reasonable to call rtc_stop from pc_basic_device_init, inside the same
if (!xen_available()) introduce by the next patch?
Otherwise I could implement functions to walk the isa bus, similarly to
pci_for_each_device.
This is just an example:
diff --git a/hw/mc146818rtc.c b/hw/mc146818rtc.c
index 2aaca2f..568c540 100644
--- a/hw/mc146818rtc.c
+++ b/hw/mc146818rtc.c
@@ -667,6 +667,28 @@ ISADevice *rtc_init(int base_year, qemu_irq intercept_irq)
return dev;
}
+void rtc_stop(ISADevice *dev)
+{
+ RTCState *s = DO_UPCAST(RTCState, dev, dev);
+
+ qemu_del_timer(s->periodic_timer);
+ qemu_del_timer(s->second_timer);
+ qemu_del_timer(s->second_timer2);
+#ifdef TARGET_I386
+ if (rtc_td_hack) {
+ qemu_del_timer(s->coalesced_timer);
+ }
+#endif
+ qemu_free_timer(s->periodic_timer);
+ qemu_free_timer(s->second_timer);
+ qemu_free_timer(s->second_timer2);
+#ifdef TARGET_I386
+ if (rtc_td_hack) {
+ qemu_free_timer(s->coalesced_timer);
+ }
+#endif
+}
+
static ISADeviceInfo mc146818rtc_info = {
.qdev.name = "mc146818rtc",
.qdev.size = sizeof(RTCState),
diff --git a/hw/mc146818rtc.h b/hw/mc146818rtc.h
index 575968c..aa2b8ab 100644
--- a/hw/mc146818rtc.h
+++ b/hw/mc146818rtc.h
@@ -8,5 +8,6 @@
ISADevice *rtc_init(int base_year, qemu_irq intercept_irq);
void rtc_set_memory(ISADevice *dev, int addr, int val);
void rtc_set_date(ISADevice *dev, const struct tm *tm);
+void rtc_stop(ISADevice *dev);
#endif /* !MC146818RTC_H */
diff --git a/hw/pc.c b/hw/pc.c
index a0ae981..d734f75 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -1145,6 +1145,8 @@ void pc_basic_device_init(qemu_irq *gsi,
if (!xen_available()) {
pit = pit_init(0x40, 0);
+ } else {
+ rtc_stop(*rtc_state);
}
pcspk_init(pit);
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