Index: /trunk/src/VBox/Runtime/r0drv/nt/memobj-r0drv-nt.cpp
===================================================================
--- /trunk/src/VBox/Runtime/r0drv/nt/memobj-r0drv-nt.cpp	(revision 38957)
+++ /trunk/src/VBox/Runtime/r0drv/nt/memobj-r0drv-nt.cpp	(revision 38958)
@@ -497,5 +497,5 @@
 DECLHIDDEN(int) rtR0MemObjNativeEnterPhys(PPRTR0MEMOBJINTERNAL ppMem, RTHCPHYS Phys, size_t cb, uint32_t uCachePolicy)
 {
-    AssertReturn(uCachePolicy == RTMEM_CACHE_POLICY_DONT_CARE, VERR_NOT_SUPPORTED);
+    AssertReturn(uCachePolicy == RTMEM_CACHE_POLICY_DONT_CARE || uCachePolicy == RTMEM_CACHE_POLICY_MMIO, VERR_NOT_SUPPORTED);
 
     /*
@@ -780,5 +780,6 @@
         PHYSICAL_ADDRESS Phys;
         Phys.QuadPart = pMemNtToMap->Core.u.Phys.PhysBase;
-        void *pv = MmMapIoSpace(Phys, pMemNtToMap->Core.cb, MmCached); /** @todo add cache type to fProt. */
+        void *pv = MmMapIoSpace(Phys, pMemNtToMap->Core.cb,
+                                pMemNtToMap->Core.u.Phys.uCachePolicy == RTMEM_CACHE_POLICY_MMIO ? MmNonCached : MmCached);
         if (pv)
         {