--- a/xen/arch/x86/hvm/rtc.c
+++ b/xen/arch/x86/hvm/rtc.c
@@ -50,6 +50,23 @@ static void rtc_set_time(RTCState *s);
 static inline int from_bcd(RTCState *s, int a);
 static inline int convert_hour(RTCState *s, int hour);
 
+#include <xen/symbols.h>//temp
+#define LOGIDX_MASK 0xf//temp
+static struct {//temp
+ s_time_t time;
+ void*caller;
+} log[LOGIDX_MASK + 1];
+static unsigned logidx;//temp
+static void pt_off(int line) {//temp
+ unsigned i, idx = logidx;
+ printk("pt off #%d @%"PRIx64"\n", line, NOW());
+ for(i = idx; i <= idx + LOGIDX_MASK; ++i) {
+  if(!log[i & LOGIDX_MASK].caller) continue;
+  printk("pt irq @%"PRIx64, log[i & LOGIDX_MASK].time);
+  print_symbol(" (%s)\n", (unsigned long)log[i & LOGIDX_MASK].caller);
+ }
+}
+
 static void rtc_update_irq(RTCState *s)
 {
     struct domain *d = vrtc_domain(s);
@@ -68,6 +85,7 @@ static void rtc_update_irq(RTCState *s)
 
     hvm_isa_irq_deassert(d, RTC_IRQ);
     if ( irqf )
+log[logidx & LOGIDX_MASK].time = NOW(), log[logidx++ & LOGIDX_MASK].caller = __builtin_return_address(0),//temp
         hvm_isa_irq_assert(d, RTC_IRQ);
 }
 
@@ -81,12 +99,14 @@ void rtc_periodic_interrupt(void *opaque
         s->hw.cmos_data[RTC_REG_C] |= RTC_PF;
         rtc_update_irq(s);
     }
-    else if ( ++(s->pt_dead_ticks) >= 10 )
+    else if ( ++(s->pt_dead_ticks) >= 250 )
     {
         /* VM is ignoring its RTC; no point in running the timer */
+pt_off(__LINE__);//temp
         destroy_periodic_time(&s->pt);
         s->pt_code = 0;
     }
+else if(s->pt_code) rtc_update_irq(s);//todo?
     spin_unlock(&s->lock);
 }
 
@@ -114,6 +134,7 @@ static void rtc_timer_update(RTCState *s
         {
             if ( period_code != s->pt_code )
             {
+printk("pt on: %d @%"PRIx64"\n", period_code, NOW());//temp
                 s->pt_code = period_code;
                 period = 1 << (period_code - 1); /* period in 32 Khz cycles */
                 period = DIV_ROUND(period * 1000000000ULL, 32768); /* in ns */
@@ -125,6 +146,7 @@ static void rtc_timer_update(RTCState *s
         }
         /* fall through */
     default:
+pt_off(__LINE__);//temp
         destroy_periodic_time(&s->pt);
         s->pt_code = 0;
         break;
@@ -451,6 +473,9 @@ static int rtc_ioport_write(void *opaque
             rtc_timer_update(s);
         break;
     case RTC_REG_B:
+printk("B=%02x [A:%02x B:%02x C:%02x pt:%d/%d] @%"PRIx64"\n",//temp
+       data, s->hw.cmos_data[RTC_REG_A], orig, s->hw.cmos_data[RTC_REG_C],//temp
+       s->pt_code, s->pt_dead_ticks, NOW());//temp
         if ( data & RTC_SET )
         {
             /* set mode: reset UIP mode */
@@ -474,6 +499,7 @@ static int rtc_ioport_write(void *opaque
          */
         rtc_update_irq(s);
         s->hw.cmos_data[RTC_REG_B] = data;
+if((data & RTC_PIE) && !(orig & RTC_PIE)) rtc_timer_update(s);//todo?
         if ( (data ^ orig) & RTC_SET )
             check_update_timer(s);
         if ( (data ^ orig) & (RTC_24H | RTC_DM_BINARY | RTC_SET) )
@@ -629,6 +655,7 @@ static uint32_t rtc_ioport_read(RTCState
     case RTC_REG_C:
         ret = s->hw.cmos_data[s->hw.cmos_index];
         s->hw.cmos_data[RTC_REG_C] = 0x00;
+printk("C=%02x pt=%d/%d @%"PRIx64"\n", ret, s->pt_code, s->pt_dead_ticks, NOW());//temp
         rtc_update_irq(s);
         check_update_timer(s);
         alarm_timer_update(s);
@@ -730,6 +757,8 @@ void rtc_reset(struct domain *d)
     destroy_periodic_time(&s->pt);
     s->pt_code = 0;
     s->pt.source = PTSRC_isa;
+s->hw.cmos_data[RTC_REG_B] &= ~(RTC_PIE|RTC_AIE|RTC_UIE);//todo?
+s->hw.cmos_data[RTC_REG_C] = 0;//todo?
 }
 
 void rtc_init(struct domain *d)