struct _KAPC *Apc,
      PKNORMAL_ROUTINE *NormalRoutine,
      PVOID *NormalContext,
      PVOID *SystemArgument1,
      PVOID *SystemArgument2

Routine Description:

    This is the kernel apc routine.  It is called for all notifies,
    regardless of what form of notification the caller requested.

    We compute the postblock address from the apc object address.
    IoStatus is set.  SystemEvent and UserEvent will be signalled
    as appropriate.  If the user requested an APC, then NormalRoutine
    will be set at entry and executed when we exit.  The PostBlock
    is freed here.


    Apc - pointer to apc object

    NormalRoutine - Will be called when we return

    NormalContext - will be 1st argument to normal routine, ApcContext
                    passed in when NtNotifyChangeKey was called

    SystemArgument1 -  IN: Status value for IoStatusBlock
                      OUT: Ptr to IoStatusBlock (2nd arg to user apc routine)

    SystemArgument2 - Pointer to the PostBlock

Return Value: