struct DBGKD_READ_WRITE_IO_EXTENDED32

typedef struct _DBGKD_READ_WRITE_IO_EXTENDED32
{
     ULONG DataSize;
     ULONG InterfaceType;
     ULONG BusNumber;
     ULONG AddressSpace;
     ULONG IoAddress;
     ULONG DataValue;
} DBGKD_READ_WRITE_IO_EXTENDED32, *PDBGKD_READ_WRITE_IO_EXTENDED32;

Windows Vista Kernel Structures