internal static void KernelUnmapPhysicalMemory(UIntPtr startAddr,
                                                UIntPtr limitAddr)
 {
     if (useAddressTranslation)
     {
         if (VMManager.IsPermaMapped(startAddr, limitAddr))
         {
             return; // nothing to do
         }
         else
         {
             VMManager.UnmapPhysicalMemory(KernelRangeWrapper,
                                           Process.kernelProcess,
                                           startAddr, limitAddr);
         }
     }
     // else do nothing
 }