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Files Reference

mpqn Special File


Provides access to multiprotocol adapters by way of the Multiprotocol Quad Port (MPQP) device handler.


The /dev/mpqn character special file provides access to the MPQP device handler for the purpose of providing access to a synchronous network. The MPQP device handler supports multiple adapters.

Usage Considerations

When accessing the MPQP device handler, the following should be taken into account:

Driver initialization and termination

The device handler may be loaded and unloaded. The handler supports the configuration calls to initialize and terminate itself.

Special file support

Calls other than the open and close subroutine calls are discussed in relation to the mode in which the device handler is operating.

Subroutine Support

The MPQP device handler supports the open, close, read, write, and ioctl subroutines in the following manner:

Error Codes

The following error codes may be returned when accessing the device handler through the /dev/mpqn special file:

ECHRNG Indicates that the channel number is out of range.
EAGAIN Indicates that the maximum number of direct memory accesses (DMAs) was reached, so that the handler cannot get memory for internal control structures.
EBUSY Indicates one of the following:
  • The port is not in correct state.
  • The port should be configured, but is not opened or started.
  • The port state is not opened for start of an ioctl operation.
  • The port is not started or is not in data-transfer state.
EIO Indicates that the handler could not queue the request to the adapter.
EFAULT Indicates that the cross-memory copy service failed.
EINTR Indicates that the sleep was interrupted by a signal.
EINVAL Indicates one of the following:
  • The port not set up properly.
  • The handler could not set up structures for write.
  • The port is not valid.
  • A select operation was called by a kernel process.
  • The specified physical-link parameter is not valid for that port.
  • The read was called by a kernel process.
ENOMEM Indicates one of the following:
  • No mbuf or mbuf clusters are available.
  • The total data length is more than a page.
  • There is no memory for internal structures.
ENOMSG Indicates that the status-queue pointer is null, and there are no entries.
ENOTREADY Indicates that the port state in define device structure (DDS) is not in Data Transfer mode or that the implicit halt of port failed.
ENXIO Indicates one of the following:
  • The port has not been started successfully.
  • An invalid adapter number was specified.
  • The channel number is illegal.
  • The adapter is already open in Diagnostic mode.
  • The adapter control block (ACB) pointer is null or does not exist.
  • The registration of the interrupt handler failed.
  • The port does not exist or is not in proper state.
  • The adapter number is out of range.

The communication device handler chapter defines specific errors returned on each subroutine call.

Related Information

The close subroutine, open subroutine, read or readx subroutine, write or writex subroutine, ioctl subroutine.

MPQP Device Handler Interface Overview in AIX 5L Version 5.2 Kernel Extensions and Device Support Programming Concepts.

Special Files Overview .

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