Index: /trunk/include/VBox/vmm/pdmdev.h
===================================================================
--- /trunk/include/VBox/vmm/pdmdev.h	(revision 40936)
+++ /trunk/include/VBox/vmm/pdmdev.h	(revision 40937)
@@ -1438,4 +1438,12 @@
 
     /**
+     * Calculates an IRQ tag for a timer event.
+     *  
+     * @returns The IRQ tag. 
+     * @param   pDevIns         Device instance of the APIC.
+     */
+    DECLR3CALLBACKMEMBER(uint32_t, pfnCalcIrqTag,(PPDMDEVINS pDevIns));
+
+    /**
      * Modifies APIC-related bits in the CPUID feature mask.
      *
@@ -1525,5 +1533,5 @@
 
 /** Current PDMAPICHLP version number. */
-#define PDM_APICHLPR3_VERSION                   PDM_VERSION_MAKE(0xfff3, 1, 0)
+#define PDM_APICHLPR3_VERSION                   PDM_VERSION_MAKE(0xfff3, 2, 0)
 
 
Index: /trunk/src/VBox/Devices/PC/DevAPIC.cpp
===================================================================
--- /trunk/src/VBox/Devices/PC/DevAPIC.cpp	(revision 40936)
+++ /trunk/src/VBox/Devices/PC/DevAPIC.cpp	(revision 40937)
@@ -1699,5 +1699,6 @@
     if (!(pApic->lvt[APIC_LVT_TIMER] & APIC_LVT_MASKED)) {
         LogFlow(("apic_timer: trigger irq\n"));
-        apic_set_irq(pDev, pApic, pApic->lvt[APIC_LVT_TIMER] & 0xff, APIC_TRIGGER_EDGE, 0 /*uTagSrc*/);
+        apic_set_irq(pDev, pApic, pApic->lvt[APIC_LVT_TIMER] & 0xff, APIC_TRIGGER_EDGE, 
+                     pDev->CTX_SUFF(pApicHlp)->pfnCalcIrqTag(pDevIns));
 
         if (   (pApic->lvt[APIC_LVT_TIMER] & APIC_LVT_TIMER_PERIODIC)
Index: /trunk/src/VBox/VMM/VMMR3/PDMDevMiscHlp.cpp
===================================================================
--- /trunk/src/VBox/VMM/VMMR3/PDMDevMiscHlp.cpp	(revision 40936)
+++ /trunk/src/VBox/VMM/VMMR3/PDMDevMiscHlp.cpp	(revision 40937)
@@ -239,4 +239,19 @@
 
 
+/** @interface_method_impl{PDMAPICHLPR3,pfnCalcIrqTag} */
+static DECLCALLBACK(uint32_t) pdmR3ApicHlp_CalcIrqTag(PPDMDEVINS pDevIns)
+{
+    PDMDEV_ASSERT_DEVINS(pDevIns);
+    PVM pVM = pDevIns->Internal.s.pVMR3;
+
+    pdmLock(pVM);
+    uint32_t uTagSrc = pdmCalcIrqTag(pVM, pDevIns->idTracing);
+    pdmUnlock(pVM);
+
+    LogFlow(("pdmR3ApicHlp_CalcIrqTag: caller='%s'/%d: returns %#x\n", pDevIns->pReg->szName, pDevIns->iInstance, uTagSrc));
+    return uTagSrc;
+}
+
+
 /** @interface_method_impl{PDMAPICHLPR3,pfnChangeFeature} */
 static DECLCALLBACK(void) pdmR3ApicHlp_ChangeFeature(PPDMDEVINS pDevIns, PDMAPICVERSION enmVersion)
@@ -359,4 +374,5 @@
     pdmR3ApicHlp_SetInterruptFF,
     pdmR3ApicHlp_ClearInterruptFF,
+    pdmR3ApicHlp_CalcIrqTag,
     pdmR3ApicHlp_ChangeFeature,
     pdmR3ApicHlp_GetCpuId,