Re: [Qemu-devel] [RFC PATCH v4 01/25] acpi: accurate overflow check

[Paolo Bonzini]

On 07/11/2014 11:31, Pavel Dovgalyuk wrote:
> Compare clock in ns, because acpi_pm_tmr_update uses rounded
> to ns value instead of ticks.
> 
> Signed-off-by: Pavel Dovgalyuk <address@hidden>
> ---
>  hw/acpi/core.c |    7 +++++--
>  1 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/acpi/core.c b/hw/acpi/core.c
> index a7368fb..51913d6 100644
> --- a/hw/acpi/core.c
> +++ b/hw/acpi/core.c
> @@ -376,8 +376,11 @@ static void acpi_notify_wakeup(Notifier *notifier, void 
> *data)
>  /* ACPI PM1a EVT */
>  uint16_t acpi_pm1_evt_get_sts(ACPIREGS *ar)
>  {
> -    int64_t d = acpi_pm_tmr_get_clock();
> -    if (d >= ar->tmr.overflow_time) {
> +    /* Compare ns-clock, not PM timer ticks, because
> +       acpi_pm_tmr_update function uses ns for setting the timer. */
> +    int64_t d = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
> +    if (d >= muldiv64(ar->tmr.overflow_time,
> +                      get_ticks_per_sec(), PM_TIMER_FREQUENCY)) {
>          ar->pm1.evt.sts |= ACPI_BITMASK_TIMER_STATUS;
>      }
>      return ar->pm1.evt.sts;
> 

Reviewed-by: Paolo Bonzini <address@hidden>

The same muldiv64 is in acpi_pm_tmr_update, it could be extracted to a
separate function if you so wish.

Paolo