[PATCH v2 1/1] goldfish_rtc: keep time offset when resetting

[PATCH v2 1/1] goldfish_rtc: keep time offset when resetting

[Heinrich Schuchardt]

Currently resetting the leads to resynchronizing the Goldfish RTC with the
system clock of the host. In real hardware an RTC reset would not change
the wall time. Other RTCs like pl031 do not show this behavior.

Move the synchronization of the RTC with the system clock to the instance
realization.

Cc: qemu-stable@nongnu.org
Reported-by: Frederik Du Toit Lotter <fred.lotter@canonical.com>
Fixes: 9a5b40b8427 ("hw: rtc: Add Goldfish RTC device")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
v2:
	Remove a superfluous intialization to nul.
	Add Cc:, Fixes:, and Reviewed-by: tags.
v1:
	https://lore.kernel.org/qemu-devel/CAAhSdy0-we9B19wRRqk_rRFkjY2LPPMRGaTdE=_4Ge_pCR4Y4Q@mail.gmail.com/T/
---
 hw/rtc/goldfish_rtc.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/hw/rtc/goldfish_rtc.c b/hw/rtc/goldfish_rtc.c
index 0f1b53e0e4..d83cc26481 100644
--- a/hw/rtc/goldfish_rtc.c
+++ b/hw/rtc/goldfish_rtc.c
@@ -239,15 +239,8 @@ static const VMStateDescription goldfish_rtc_vmstate = {
 static void goldfish_rtc_reset(DeviceState *dev)
 {
     GoldfishRTCState *s = GOLDFISH_RTC(dev);
-    struct tm tm;
 
     timer_del(s->timer);
-
-    qemu_get_timedate(&tm, 0);
-    s->tick_offset = mktimegm(&tm);
-    s->tick_offset *= NANOSECONDS_PER_SECOND;
-    s->tick_offset -= qemu_clock_get_ns(rtc_clock);
-    s->tick_offset_vmstate = 0;
     s->alarm_next = 0;
     s->alarm_running = 0;
     s->irq_pending = 0;
@@ -258,6 +251,7 @@ static void goldfish_rtc_realize(DeviceState *d, Error **errp)
 {
     SysBusDevice *dev = SYS_BUS_DEVICE(d);
     GoldfishRTCState *s = GOLDFISH_RTC(d);
+    struct tm tm;
 
     memory_region_init_io(&s->iomem, OBJECT(s),
                           &goldfish_rtc_ops[s->big_endian], s,
@@ -267,6 +261,11 @@ static void goldfish_rtc_realize(DeviceState *d, Error **errp)
     sysbus_init_irq(dev, &s->irq);
 
     s->timer = timer_new_ns(rtc_clock, goldfish_rtc_interrupt, s);
+
+    qemu_get_timedate(&tm, 0);
+    s->tick_offset = mktimegm(&tm);
+    s->tick_offset *= NANOSECONDS_PER_SECOND;
+    s->tick_offset -= qemu_clock_get_ns(rtc_clock);
 }
 
 static const Property goldfish_rtc_properties[] = {
-- 
2.48.1

Re: [PATCH v2 1/1] goldfish_rtc: keep time offset when resetting

[Philippe Mathieu-Daudé]

On 21/3/25 23:12, Heinrich Schuchardt wrote:
> Currently resetting the leads to resynchronizing the Goldfish RTC with the
> system clock of the host. In real hardware an RTC reset would not change
> the wall time. Other RTCs like pl031 do not show this behavior.
> 
> Move the synchronization of the RTC with the system clock to the instance
> realization.
> 
> Cc: qemu-stable@nongnu.org
> Reported-by: Frederik Du Toit Lotter <fred.lotter@canonical.com>
> Fixes: 9a5b40b8427 ("hw: rtc: Add Goldfish RTC device")
> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> ---
> v2:
> 	Remove a superfluous intialization to nul.
> 	Add Cc:, Fixes:, and Reviewed-by: tags.
> v1:
> 	https://lore.kernel.org/qemu-devel/CAAhSdy0-we9B19wRRqk_rRFkjY2LPPMRGaTdE=_4Ge_pCR4Y4Q@mail.gmail.com/T/
> ---
>   hw/rtc/goldfish_rtc.c | 13 ++++++-------
>   1 file changed, 6 insertions(+), 7 deletions(-)

Thanks, patch queued!