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

[Anup Patel <anup@brainfault.org>]

On Fri, Mar 21, 2025 at 1:43 PM Heinrich Schuchardt
<heinrich.schuchardt@canonical.com> wrote:
>
> Currently resetting 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.
>
> Reported-by: Frederik Du Toit Lotter <fred.lotter@canonical.com>
> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>

LGTM.

Reviewed-by: Anup Patel <anup@brainfault.org>

Regards,
Anup

> ---
>  hw/rtc/goldfish_rtc.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/hw/rtc/goldfish_rtc.c b/hw/rtc/goldfish_rtc.c
> index 0f1b53e0e4..203a343511 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 +261,12 @@ 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);
> +    s->tick_offset_vmstate = 0;
>  }
>
>  static const Property goldfish_rtc_properties[] = {
> --
> 2.48.1
>
>