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Date: Tue, 9 Jun 2009 18:48:18 +0300
From: Gleb Natapov <gleb@redhat.com>
Subject: Re: [Qemu-devel] [PATCHv2] Add rtc reset function.
Message-ID: <20090609154818.GL5558@redhat.com>
References: <20090609092605.GU27210@redhat.com>
	<20090609154533.GA9183@amt.cnet>
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To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: qemu-devel@nongnu.org

On Tue, Jun 09, 2009 at 12:45:33PM -0300, Marcelo Tosatti wrote:
> On Tue, Jun 09, 2009 at 12:26:05PM +0300, Gleb Natapov wrote:
> > On reset:
> > Periodic Interrupt Enable (PIE) bit is cleared to zero
> > Alarm Interrupt Enable (AIE) bit is cleared to zero
> > Update ended Interrupt Flag (UF) bit is cleared to zero
> > Interrupt Request status Flag (IRQF) bit is cleared to zero
> > Periodic Interrupt Flag (PF) bit is cleared to zero
> > Alarm Interrupt Flag (AF) bit is cleared to zero
> > Square Wave output Enable (SQWE) zero
> > 
> > Signed-off-by: Gleb Natapov <gleb@redhat.com>
> > diff --git a/hw/mc146818rtc.c b/hw/mc146818rtc.c
> > index 888b85a..8c446e1 100644
> > --- a/hw/mc146818rtc.c
> > +++ b/hw/mc146818rtc.c
> > @@ -57,6 +57,11 @@
> >  #define REG_B_SQWE 0x08
> >  #define REG_B_DM   0x04
> >  
> > +#define REG_C_UF   0x10
> > +#define REG_C_IRQF 0x80
> > +#define REG_C_PF   0x40
> > +#define REG_C_AF   0x20
> > +
> >  struct RTCState {
> >      uint8_t cmos_data[128];
> >      uint8_t cmos_index;
> > @@ -568,6 +573,21 @@ static int rtc_load_td(QEMUFile *f, void *opaque, int version_id)
> >  }
> >  #endif
> >  
> > +static void rtc_reset(void *opaque)
> > +{
> > +    RTCState *s = opaque;
> > +
> > +    s->cmos_data[RTC_REG_B] &= ~(REG_B_PIE | REG_B_AIE | REG_B_SQWE);
> > +    s->cmos_data[RTC_REG_C] &= ~(REG_C_UF | REG_C_IRQF | REG_C_PF | REG_C_AF);
> > +
> > +    qemu_irq_lower(s->irq);
> > +
> > +#ifdef TARGET_I386
> > +    if (rtc_td_hack)
> > +	    s->irq_coalesced = 0;
> > +#endif
> > +}
> 
> Don't you need to cancel the timer before clearing cmos_data[]?
I believe when this callback runs guest is already stopped, so there is
not difference.

--
			Gleb.