Determining extended capability of a channel path

An apparatus for informing an operating system whether an extension to a Fibre Channel protocol is supported by a channel path in an input/output (I/O) processing system, the apparatus comprising:

• a channel subsystem in a host computer system for communication with a control unit via a channel path, the channel subsystem including one or more channel paths including one or more channels configured to be coupled to a control unit configured to operate and control one or more I/O devices, the channel subsystem configured to direct information flow between memory and one or more I/O devices via the channel path, the channel subsystem configured to perform a method comprising:
• receiving a request at the channel subsystem from an operating system in the host computer system to provide a channel path description for the channel path;
• and
• outputting from the channel subsystem to the operating system, a channel path description block including the channel path description for the channel path in response to the request, wherein the channel path description block includes:
• a descriptor field (DESC) indicating that the channel path supports a Fibre Channel protocol for commanding an I/O operation;
• and
• an extension support indicator field (F) specifying whether the channel path supports an extension to the Fibre Channel protocol, the extension supporting transport control word (TCW) channel programs configured to support at least one transport command control block (TCCB), the TCCB configured to be sent from the channel subsystem to the control unit as a single entity and configured to hold one or more commands for performing an I/O operation.

A method for informing an operating system whether an extension to a Fibre Channel protocol is supported by a channel path in an input/output (I/O) processing system, the method comprising:

• receiving a request at a channel subsystem in a host computer system from an operating system in the host computer system to provide a channel path description for a channel path, wherein the channel path includes a channel configured to be coupled to a control unit configured to operate and control one or more I/O devices, the channel subsystem configured to direct information flow between memory and the control unit via the channel path;
• and
• outputting from the channel subsystem to the operating system a channel path description block including the channel path description for the channel path in response to the request, wherein the channel path description block includes:
• a descriptor field indicating that the channel path supports a Fibre Channel protocol for commanding an I/O operation;
• and
• an extension support indicator field specifying whether the channel path supports an extension to the Fibre Channel protocol, the extension supporting transport control word (TCW) channel programs configured to support at least one transport command control block (TCCB), the TCCB configured to be sent from the channel subsystem to the control unit as a single entity and configured to hold one or more commands for performing an I/O operation.