Re: [Xen-devel] [PATCH, v3] x86/HVM: RTC periodic timer emulation adjustments

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 31.08.12 at 18:50, Keir Fraser <keir.xen@xxxxxxxxx> wrote:
> On 31/08/2012 17:01, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
>> @@ -405,9 +407,9 @@ static int rtc_ioport_write(void *opaque
>>          break;
>>      case RTC_REG_A:
>>          /* UIP bit is read only */
>> -        s->hw.cmos_data[RTC_REG_A] = (data & ~RTC_UIP) |
>> -            (s->hw.cmos_data[RTC_REG_A] & RTC_UIP);
>> -        rtc_timer_update(s);
>> +        s->hw.cmos_data[RTC_REG_A] = (data & ~RTC_UIP) | (orig & RTC_UIP);
>> +        if ( (data ^ orig) & (RTC_RATE_SELECT | RTC_DIV_CTL) )
> 
> Please change to 'if ( (data ^ orig) & ~RTC_UIP )'. It is shorter and
> matches the style of the immediately preceding line.
> 
> Once you make this change:
> Acked-by: Keir Fraser <keir@xxxxxxx>

I made the change before committing, albeit I disagree - what
we care about here are explicitly the two fields that the original
version named. Their mask just accidentally happens to be the
complement of RTC_UIP. Whereas in the lines above we
specifically care about that one flag...

Jan


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