Index: /trunk/src/VBox/Runtime/r0drv/nt/initterm-r0drv-nt.cpp
===================================================================
--- /trunk/src/VBox/Runtime/r0drv/nt/initterm-r0drv-nt.cpp	(revision 24020)
+++ /trunk/src/VBox/Runtime/r0drv/nt/initterm-r0drv-nt.cpp	(revision 24021)
@@ -54,15 +54,10 @@
 
 /** ExSetTimerResolution, introduced in W2K. */
-PFNMYEXSETTIMERRESOLUTION   g_pfnrtNtExSetTimerResolution;
+PFNMYEXSETTIMERRESOLUTION       g_pfnrtNtExSetTimerResolution;
 /** KeFlushQueuedDpcs, introduced in XP. */
-PFNMYKEFLUSHQUEUEDDPCS      g_pfnrtNtKeFlushQueuedDpcs;
-/** HalRequestIpi, introduced in ??. */
-PFNHALREQUESTIPI            g_pfnrtNtHalRequestIpi;
-/** HalSendSoftwareInterrupt */
-PFNHALSENDSOFTWAREINTERRUPT g_pfnrtNtHalSendSoftwareInterrupt;
-/** SendIpi handler based on Windows version */
-PFNRTSENDIPI                g_pfnrtSendIpi;
-/** KeIpiGenericCall - Windows Server 2003+ only */
-PFNRTKEIPIGENERICCALL       g_pfnrtKeIpiGenericCall;
+PFNMYKEFLUSHQUEUEDDPCS          g_pfnrtNtKeFlushQueuedDpcs;
+/** KeSetSystemAffinityThread - Windows 2000+ */
+PFNRTKESETSYSTEMAFFINITYTHREAD  g_pfnrtKeSetSystemAffinityThread;
+
 
 /** Offset of the _KPRCB::QuantumEnd field. 0 if not found. */
@@ -91,7 +86,5 @@
     g_pfnrtNtExSetTimerResolution = NULL;
     g_pfnrtNtKeFlushQueuedDpcs = NULL;
-    g_pfnrtNtHalRequestIpi = NULL;
-    g_pfnrtNtHalSendSoftwareInterrupt = NULL;
-    g_pfnrtKeIpiGenericCall = NULL;
+	g_pfnrtKeSetSystemAffinityThread = NULL;
 #else
     /*
@@ -105,12 +98,6 @@
     g_pfnrtNtKeFlushQueuedDpcs = (PFNMYKEFLUSHQUEUEDDPCS)MmGetSystemRoutineAddress(&RoutineName);
 
-    RtlInitUnicodeString(&RoutineName, L"HalRequestIpi");
-    g_pfnrtNtHalRequestIpi = (PFNHALREQUESTIPI)MmGetSystemRoutineAddress(&RoutineName);
-
-    RtlInitUnicodeString(&RoutineName, L"HalSendSoftwareInterrupt");
-    g_pfnrtNtHalSendSoftwareInterrupt = (PFNHALSENDSOFTWAREINTERRUPT)MmGetSystemRoutineAddress(&RoutineName);
-
-    RtlInitUnicodeString(&RoutineName, L"KeIpiGenericCall");
-    g_pfnrtKeIpiGenericCall = (PFNRTKEIPIGENERICCALL)MmGetSystemRoutineAddress(&RoutineName);
+    RtlInitUnicodeString(&RoutineName, L"KeSetSystemAffinityThread");
+    g_pfnrtKeSetSystemAffinityThread = (PFNRTKESETSYSTEMAFFINITYTHREAD)MmGetSystemRoutineAddress(&RoutineName);
 #endif
 
@@ -123,23 +110,4 @@
     BOOLEAN fChecked = PsGetVersion(&MajorVersion, &MinorVersion, &BuildNumber, NULL);
 
-    g_pfnrtSendIpi = rtMpSendIpiDummy;
-#ifndef IPRT_TARGET_NT4
-    if (    g_pfnrtNtHalRequestIpi
-        &&  MajorVersion == 6
-        &&  MinorVersion == 0)
-    {
-        /* Vista or Windows Server 2008 */
-        g_pfnrtSendIpi = rtMpSendIpiVista;
-    }
-    else
-    if (    g_pfnrtNtHalSendSoftwareInterrupt
-        &&  MajorVersion == 6
-        &&  MinorVersion == 1)
-    {
-        /* Windows 7 or Windows Server 2008 R2 */
-        g_pfnrtSendIpi = rtMpSendIpiWin7;
-    }
-    /* Windows XP should send always send an IPI -> VERIFY */
-#endif
     KIRQL OldIrql;
     KeRaiseIrql(DISPATCH_LEVEL, &OldIrql); /* make sure we stay on the same cpu */
Index: /trunk/src/VBox/Runtime/r0drv/nt/internal-r0drv-nt.h
===================================================================
--- /trunk/src/VBox/Runtime/r0drv/nt/internal-r0drv-nt.h	(revision 24020)
+++ /trunk/src/VBox/Runtime/r0drv/nt/internal-r0drv-nt.h	(revision 24021)
@@ -41,8 +41,5 @@
 typedef ULONG (__stdcall *PFNMYEXSETTIMERRESOLUTION)(ULONG, BOOLEAN);
 typedef VOID (__stdcall *PFNMYKEFLUSHQUEUEDDPCS)(VOID);
-typedef VOID (__stdcall *PFNHALREQUESTIPI)(KAFFINITY TargetSet);
-typedef VOID (__stdcall *PFNHALSENDSOFTWAREINTERRUPT)(ULONG ProcessorNumber, KIRQL Irql);
-typedef int (__stdcall *PFNRTSENDIPI)(RTCPUID idCpu);
-typedef ULONG_PTR (__stdcall *PFNRTKEIPIGENERICCALL)(PKIPI_BROADCAST_WORKER BroadcastFunction, ULONG_PTR  Context);
+typedef VOID (__stdcall *PFNRTKESETSYSTEMAFFINITYTHREAD)(KAFFINITY);
 
 /*******************************************************************************
@@ -52,16 +49,8 @@
 extern PFNMYEXSETTIMERRESOLUTION    g_pfnrtNtExSetTimerResolution;
 extern PFNMYKEFLUSHQUEUEDDPCS       g_pfnrtNtKeFlushQueuedDpcs;
-extern PFNHALREQUESTIPI             g_pfnrtNtHalRequestIpi;
-extern PFNHALSENDSOFTWAREINTERRUPT  g_pfnrtNtHalSendSoftwareInterrupt;
-extern PFNRTSENDIPI                 g_pfnrtSendIpi;
-extern PFNRTKEIPIGENERICCALL        g_pfnrtKeIpiGenericCall;
+extern PFNRTKESETSYSTEMAFFINITYTHREAD g_pfnrtKeSetSystemAffinityThread;
 extern uint32_t                     g_offrtNtPbQuantumEnd;
 extern uint32_t                     g_cbrtNtPbQuantumEnd;
 extern uint32_t                     g_offrtNtPbDpcQueueDepth;
-
-
-int rtMpSendIpiVista(RTCPUID idCpu);
-int rtMpSendIpiWin7(RTCPUID idCpu);
-int rtMpSendIpiDummy(RTCPUID idCpu);
 
 RT_C_DECLS_END
Index: /trunk/src/VBox/Runtime/r0drv/nt/mp-r0drv-nt.cpp
===================================================================
--- /trunk/src/VBox/Runtime/r0drv/nt/mp-r0drv-nt.cpp	(revision 24020)
+++ /trunk/src/VBox/Runtime/r0drv/nt/mp-r0drv-nt.cpp	(revision 24021)
@@ -347,31 +347,4 @@
 }
 
-#ifndef IPRT_TARGET_NT4
-
-ULONG_PTR rtMpIpiGenericCall(ULONG_PTR  Argument)
-{
-    return 0;
-}
-
-int rtMpSendIpiVista(RTCPUID idCpu)
-{
-    g_pfnrtKeIpiGenericCall(rtMpIpiGenericCall, 0);
-////    g_pfnrtNtHalRequestIpi(1 << idCpu);
-    return VINF_SUCCESS;
-}
-
-int rtMpSendIpiWin7(RTCPUID idCpu)
-{
-    g_pfnrtKeIpiGenericCall(rtMpIpiGenericCall, 0);
-////    g_pfnrtNtHalSendSoftwareInterrupt(idCpu, DISPATCH_LEVEL);
-    return VINF_SUCCESS;
-}
-#endif /* IPRT_TARGET_NT4 */
-
-int rtMpSendIpiDummy(RTCPUID idCpu)
-{
-    return VERR_NOT_IMPLEMENTED;
-}
-
 RTDECL(int) RTMpPokeCpu(RTCPUID idCpu)
 {
@@ -380,8 +353,4 @@
               ? VERR_CPU_NOT_FOUND
               : VERR_CPU_OFFLINE;
-
-    int rc = g_pfnrtSendIpi(idCpu);
-    if (rc == VINF_SUCCESS)
-        return rc;
 
     /* Fallback. */
@@ -407,5 +376,5 @@
 
     /* Assuming here that high importance DPCs will be delivered immediately; or at least an IPI will be sent immediately.
-     * @note: not true on at least Vista & Windows 7
+     * @note: seems to be true on Vista
      */
     BOOLEAN bRet = KeInsertQueueDpc(&aPokeDpcs[idCpu], 0, 0);
Index: /trunk/src/VBox/Runtime/r0drv/nt/thread-r0drv-nt.cpp
===================================================================
--- /trunk/src/VBox/Runtime/r0drv/nt/thread-r0drv-nt.cpp	(revision 24020)
+++ /trunk/src/VBox/Runtime/r0drv/nt/thread-r0drv-nt.cpp	(revision 24021)
@@ -170,5 +170,10 @@
     Assert(KeGetCurrentIrql() <= DISPATCH_LEVEL);
 
+#ifndef IPRT_TARGET_NT4
+    Assert(g_pfnrtKeSetSystemAffinityThread);
+    g_pfnrtKeSetSystemAffinityThread((KAFFINITY)1 << KeGetCurrentProcessorNumber());
+#else
     KeRaiseIrql(DISPATCH_LEVEL, &pState->uchOldIrql);
+#endif
     RT_ASSERT_PREEMPT_CPUID_DISABLE(pState);
 }
@@ -180,5 +185,10 @@
 
     RT_ASSERT_PREEMPT_CPUID_RESTORE(pState);
+#ifndef IPRT_TARGET_NT4
+    Assert(g_pfnrtKeSetSystemAffinityThread);
+    g_pfnrtKeSetSystemAffinityThread(KeQueryActiveProcessors());
+#else
     KeLowerIrql(pState->uchOldIrql);
+#endif
     pState->uchOldIrql = 255;
 }