Re: [Qemu-devel] [PATCH 1/4] rtc: fix 12-hour mode

[Mark Wu <wudxw@linux.vnet.ibm.com>]

On 11/22/2011 02:00 AM, Paolo Bonzini wrote:
> Hours in 12-hour mode are in the 1-12 range, not 0-11.
Interesting. I would like to know how you could find this problem. It 
seems linux driver never changes the format  and 24-hour is default in 
rtc emulation code. So how did it expose and how to test it?

Thanks.
> Signed-off-by: Paolo Bonzini<pbonzini@redhat.com>
> ---
>   hw/mc146818rtc.c |   11 +++++++----
>   1 files changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/hw/mc146818rtc.c b/hw/mc146818rtc.c
> index 2aaca2f..14c8cb9 100644
> --- a/hw/mc146818rtc.c
> +++ b/hw/mc146818rtc.c
> @@ -296,9 +296,11 @@ static void rtc_set_time(RTCState *s)
>       tm->tm_sec = rtc_from_bcd(s, s->cmos_data[RTC_SECONDS]);
>       tm->tm_min = rtc_from_bcd(s, s->cmos_data[RTC_MINUTES]);
>       tm->tm_hour = rtc_from_bcd(s, s->cmos_data[RTC_HOURS]&  0x7f);
> -    if (!(s->cmos_data[RTC_REG_B]&  REG_B_24H)&&
> -        (s->cmos_data[RTC_HOURS]&  0x80)) {
> -        tm->tm_hour += 12;
> +    if (!(s->cmos_data[RTC_REG_B]&  REG_B_24H)) {
> +        tm->tm_hour %= 12;
> +        if (s->cmos_data[RTC_HOURS]&  0x80) {
> +            tm->tm_hour += 12;
> +        }
>       }
>       tm->tm_wday = rtc_from_bcd(s, s->cmos_data[RTC_DAY_OF_WEEK]) - 1;
>       tm->tm_mday = rtc_from_bcd(s, s->cmos_data[RTC_DAY_OF_MONTH]);
> @@ -320,7 +324,8 @@ static void rtc_copy_date(RTCState *s)
>           s->cmos_data[RTC_HOURS] = rtc_to_bcd(s, tm->tm_hour);
>       } else {
>           /* 12 hour format */
> -        s->cmos_data[RTC_HOURS] = rtc_to_bcd(s, tm->tm_hour % 12);
> +        int h = (tm->tm_hour % 12) ? tm->tm_hour % 12 : 12;
> +        s->cmos_data[RTC_HOURS] = rtc_to_bcd(s, h);
>           if (tm->tm_hour>= 12)
>               s->cmos_data[RTC_HOURS] |= 0x80;
>       }