Re: [Qemu-devel] [PATCH v5 3/3] Change driftfix default value to slew

[Anthony Liguori <anthony@codemonkey.ws>]

Crístian Viana <vianac@linux.vnet.ibm.com> writes:

> Windows 2008+ is very sensitive to missed ticks. The RTC is used by default as
> the time source. If driftfix is not enabled, Windows is prone to
> blue screening.
>
> Signed-off-by: Crístian Viana <vianac@linux.vnet.ibm.com>

Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>

Regards,

Anthony Liguori

> ---
>  hw/mc146818rtc.c |    2 +-
>  vl.c             |   11 ++++++++++-
>  2 files changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/hw/mc146818rtc.c b/hw/mc146818rtc.c
> index 3777f85..dfd7ee6 100644
> --- a/hw/mc146818rtc.c
> +++ b/hw/mc146818rtc.c
> @@ -686,7 +686,7 @@ 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/vl.c b/vl.c
> index 1329c30..3ae43fc 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -559,7 +559,16 @@ static void configure_rtc(QemuOpts *opts)
>  
>              qdev_prop_register_global_list(slew_lost_ticks);
>          } else if (!strcmp(value, "none")) {
> -            /* discard is default */
> +            static GlobalProperty discard_lost_ticks[] = {
> +                {
> +                    .driver   = "mc146818rtc",
> +                    .property = "lost_tick_policy",
> +                    .value    = "discard",
> +                },
> +                { /* end of list */ }
> +            };
> +
> +            qdev_prop_register_global_list(discard_lost_ticks);
>          } else {
>              fprintf(stderr, "qemu: invalid option value '%s'\n", value);
>              exit(1);
> -- 
> 1.7.9.5