PROCESSING OF DATA TO DETERMINE COMPATABILITY IN AN INPUT/OUTPUT PROCESSING SYSTEM

• US 20090210884A1
• 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: Kalos, Matthew J., Yudenfriend, Harry M., Huang, Catherine C., Flanagan, John R., Ricci, Louis W., Carlson, Scott M., Bendyk, Mark P., Hathorn, Roger G., Sittmann, Gustav E., Casper, Daniel F.
• Granted Patent: US 8,196,149 B2
• Time in Patent Office: Days
• US Class Current: 719/313
• CPC Class Codes: G06F 13/385 for adaptation of a particular data processing system to different peripheral devices

Abstract

A computer program product, an apparatus, and a method for processing communications between a control unit and a channel subsystem in an input/output 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 including: sending a message from the channel subsystem to the control unit in a first mode; receiving a response from the control unit and determining from the response whether the control unit supports a message protocol; and responsive to the message protocol being supported by the control unit, sending another message using the message protocol from the channel subsystem to the control unit to determine whether the control unit supports a second mode.

Claims

1. A computer program product for processing communications between a control unit and a channel subsystem in an input/output processing system, comprising a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising:

sending a message from the channel subsystem to the control unit in a first mode;

receiving a response from the control unit and determining from the response whether the control unit supports a message protocol; and

responsive to the message protocol being supported by the control unit, sending another message using the message protocol from the channel subsystem to the control unit to determine whether the control unit supports a second mode.

2. The computer program product of claim 1, wherein the first mode uses a first protocol supporting Channel Command Words (CCW), and the second mode uses a second protocol supporting Transport Control Words (TCW).

3. The computer program product of claim 1, wherein the message protocol is a protocol that uses process log-in (PRLI) and process log-out (PRLO) messages.

4. The computer program product of claim 1, wherein the message is a Request Node Identification Data (RNID) message, and the response is a RNID response.

5. The computer program product of claim 4, wherein the RNID response comprises a bit in a field that indicates whether the message protocol is supported.

6. The computer program product of claim 1, wherein determining whether the control unit supports a message protocol comprises identifying a data bit setting in a field of the response.

7. The computer program product of claim 1, further comprising receiving another response from the control unit, and determining from the another response whether the control unit supports the second mode.

8. The computer program product of claim 7, wherein determining whether the control unit supports the second mode comprises identifying a data bit setting in a field of the another response.

9. The computer program product of claim 7, wherein the another message is a Process Log-in (PRLI) message and the another response is a PRLI response.

10. The computer program product of claim 9, wherein determining whether the control unit supports the second mode comprises identifying a data bit setting in a flags field of the another response.

11. The computer program product of claim 1, wherein:

the message is an identification request message, and the first mode uses a first protocol supporting Channel Command Words (CCW);

the message protocol is a Process Log-in (PRLI) message protocol, and the response is an identification request response comprising a bit in a field that indicates whether the PRLI message protocol is supported;

determining comprises determining from the bit whether the control unit supports the PRLI message protocol;

the second mode uses a second protocol supporting Transport Control Words (TCW); and

the method further comprises initiating input/output operations to the control unit using the second mode.

12. An apparatus for processing communications in an input/output processing system, comprising:

a channel subsystem of a host computer system in communication with a control unit capable of commanding and determining status of an I/O device, the channel subsystem performing;

sending a message to the control unit in a first mode;

receiving a response from the control unit and determining from the response whether the control unit supports a message protocol; and

responsive to the message protocol being supported by the control unit, sending another message using the message protocol to the control unit to determine whether the control unit supports a second mode.

13. The apparatus of claim 12, wherein the first mode uses a first protocol supporting Channel Command Words (CCW), and the second mode uses a second protocol supporting Transport Control Words (TCW).

14. The apparatus of claim 12, wherein the message protocol is a protocol that uses process log-in (PRLI) and process log-out (PRLO) messages.

15. The apparatus of claim 12, wherein the message is a Request Node Identification Data (RNID) message, and the response is a RNID response.

16. The apparatus of claim 15, wherein the RNID response comprises a bit in a field that indicates whether the message protocol is supported.

17. The apparatus of claim 12, wherein determining whether the control unit supports a message protocol comprises identifying a data bit setting in a field of the response.

18. The apparatus of claim 12, further comprising receiving another response from the control unit, and determining from the another response whether the control unit supports the second mode.

19. The apparatus of claim 18, wherein determining whether the control unit supports the second mode comprises identifying a data bit setting in a field of the another response.

20. The apparatus of claim 18, wherein the another message is a Process Log-in (PRLI) message and the another response is a PRLI response.

21. The apparatus of claim 18, wherein determining whether the control unit supports the second mode comprises identifying a data bit setting in a flags field of the another response.

22. The apparatus of claim 12, wherein:

the message is an identification request message, and the first mode uses a first protocol supporting Channel Command Words (CCW);

the message protocol is a Process Log-in (PRLI) message protocol, and the response is an identification request response comprising a bit in a field that indicates whether the PRLI message protocol is supported;

determining comprises determining from the bit whether the control unit supports the PRLI message protocol;

the second mode uses a second protocol supporting Transport Control Words (TCW); and

the channel subsystem further performs initiating input/output operations to the control unit using the second mode.

23. A method of processing communications between a control unit and a channel subsystem in an input/output processing system, the method comprising:

sending a message from the channel subsystem to the control unit in a first mode;

receiving a response from the control unit and determining from the response whether the control unit supports a message protocol; and

responsive to the message protocol being supported by the control unit, sending another message using the message protocol from the channel subsystem to the control unit to determine whether the control unit supports a second mode.

24. The method of claim 23, wherein:

the message is an identification request message, and the first mode uses a first protocol supporting Channel Command Words (CCW);

the message protocol is a Process Log-in (PRLI) message protocol, and the response is an identification request response comprising a bit in a field that indicates whether the PRLI message protocol is supported;

determining comprises determining from the bit whether the control unit supports the PRLI message protocol;

the second mode uses a second protocol supporting Transport Control Words (TCW); and

the method further comprises initiating input/output operations to the control unit using the second mode.