DETERMINING EXTENDED CAPABILITY OF A CHANNEL PATH

• US 20090210557A1
• Filed: 02/14/2008
• Published: 08/20/2009
• Est. Priority Date: 02/14/2008
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Casper, Daniel F., Gainey, Charles W. Jr.
• Granted Patent: US 8,478,915 B2
• Time in Patent Office: Days
• US Class Current: 710/2
• CPC Class Codes: G06F 13/12 using hardware independent of the central processor, e.g. channel or peripheral processor
• CPC Class Codes: G06F 13/4022 using switching circuits, e.g. switching matrix, connection or expansion network G06F13/4009 takes precedence
• CPC Class Codes: G06F 13/4282 on a serial bus, e.g. I2C bus, SPI bus on daisy chain buses G06F13/4247
• CPC Class Codes: G06F 2213/4004 Universal serial bus hub with a plurality of upstream ports
• CPC Class Codes: G06F 3/00 Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
• CPC Class Codes: G06F 3/002 Specific input/output arrangements not covered by G06F3/01 - G06F3/16 other optical apparatus G02B27/00
• CPC Class Codes: G06F 3/0635 by changing the path, e.g. traffic rerouting, path reconfiguration

Abstract

A computer program product, apparatus, and method for determining extended capability of a channel path in an I/O processing system are provided. The computer program product includes a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method. The method includes receiving a request to provide a channel path description for a channel path, where the channel path includes a channel coupled to a control unit. The method further includes outputting the channel path description for the channel path in response to the request. The channel path description includes a descriptor indicating that the channel path supports a link protocol for commanding an I/O operation, and an extension support indicator specifying whether the channel path supports an extension to the link protocol.

Claims

1. A computer program product for determining extended capability of a channel path in an input/output (I/O) processing system, the computer program product comprising:

a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising;

receiving a request to provide a channel path description for a channel path, wherein the channel path includes a channel coupled to a control unit; and

outputting the channel path description for the channel path in response to the request, wherein the channel path description includes;

a descriptor indicating that the channel path supports a link protocol for commanding an I/O operation; and

an extension support indicator specifying whether the channel path supports an extension to the link protocol.

2. The computer program product of claim 1 wherein the method farther comprises:

outputting channel description specific data (CDSD) to provide additional information associated with the descriptor in response to the request, wherein the CDSD is defined as a function of the descriptor.

3. The computer program product of claim 2 wherein the CDSD includes a maximum data count field indicating a maximum count of a sum of data count fields in all device control words (DCWs) in a transport command area (TCA) of a command message supported by the channel path when communicating via the extension to the link protocol.

4. The computer program product of claim 3 wherein the CDSD includes a validity indicator establishing validity of the maximum data count field.

5. The computer program product of claim 4 wherein the extension support indicator is the validity indicator.

6. The computer program product of claim 1 wherein the request is initiated by an operating system in the I/O processing system, and the channel path description is output from a channel subsystem in the I/O processing system.

7. The computer program product of claim 1 wherein the link protocol supports channel command word (CCW) channel programs and the extension to the link protocol supports transport control word (TCW) channel programs.

8. The computer program product of claim 1 wherein the link protocol is a Fibre Channel protocol.

9. An apparatus for determining extended capability of a channel path in an input/output (I/O) processing system, the apparatus comprising:

a channel subsystem for communication with a control unit via a channel path, the channel subsystem including one or more channels for directing information flow between memory and one or more I/O devices via the channel path, the channel subsystem performing a method comprising;

receiving a request to provide a channel path description for the channel path; and

outputting the channel path description for the channel path in response to the request, wherein the channel path description includes;

a descriptor indicating that the channel path supports a link protocol for commanding an I/O operation; and

an extension support indicator specifying whether the channel path supports an extension to the link protocol.

10. The apparatus of claim 9 wherein the method performed by the channel subsystem further comprises:

outputting channel description specific data (CDSD) to provide additional information associated with the descriptor in response to the request, wherein the CDSD is defined as a function of the descriptor.

11. The apparatus of claim 10 wherein the CDSD includes a maximum data count field indicating a maximum count of a sum of data count fields in all device control words (DCWs) in a transport command area (TCA) of a command message supported by the channel path when communicating via the extension to the link protocol.

12. The apparatus of claim 11 wherein the CDSD includes a validity indicator establishing validity of the maximum data count field.

13. The apparatus of claim 12 wherein the extension support indicator is the validity indicator.

14. The apparatus of claim 9 wherein the request is initiated by an operating system in the I/O processing system, and the channel path description is output to the operating system.

15. The apparatus of claim 9 wherein the link protocol supports channel command word (CCW) channel programs and the extension to the link protocol supports transport control word (TCW) channel programs.

16. The apparatus of claim 11 wherein the link protocol is a Fibre Channel protocol.

17. A method for determining extended capability of a channel path in an input/output (I/O) processing system, the method comprising:

receiving a request to provide a channel path description for a channel path, wherein the channel path includes a channel coupled to a control unit; and

outputting the channel path description for the channel path in response to the request, wherein the channel path description includes;

a descriptor indicating that the channel path supports a link protocol for commanding an I/O operation; and

an extension support indicator specifying whether the channel path supports an extension to the link protocol.

18. The method of claim 17 further comprising:

outputting channel description specific data (CDSD) to provide additional information associated with the descriptor in response to the request, wherein the CDSD is defined as a function of the descriptor.

19. The method of claim 18 wherein the CDSD includes a maximum data count field indicating a maximum count of a sum of data count fields in all device control words (DCWs) in a transport command area (TCA) of a command message supported by the channel path when communicating via the extension to the link protocol.

20. The method of claim 19 wherein the CDSD includes a validity indicator establishing validity of the maximum data count field.

21. The method of claim 20 wherein the extension support indicator is the validity indicator.

22. The method of claim 17 wherein the request is initiated by an operating system in the I/O processing system, and the channel path description is output from a channel subsystem in the I/O processing system.

23. The method of claim 17 wherein the link protocol supports channel command word (CCW) channel programs and the extension to the link protocol supports transport control word (TCW) channel programs.

24. The method of claim 17 wherein the link protocol is a Fibre Channel protocol.