Need support for CCW X'F7' = DSO (Define Subsystem Operation)

[Fish-Git]

In the main Hercules-390 support group, Aaron Finerman wrote on way back on Thu 12/23/2021 7:49 PM (in the "z/OS 2.4 JES2 must be cold started every time" thread):

22:15:53 HHC01315I 0:6002 CHAN: ccw F760000C 7D3F1F58=>18000000 00004100 00000000          ............
22:15:53 HHC01312I 0:6002 CHAN: stat 0E00, count 0000
22:15:53 HHC01313I 0:6002 CHAN: sense 80000000 00FFFF01 00000000 00000000 00000000 00000000 00000080 00000000
22:15:53 HHC01314I 0:6002 CHAN: sense CMDREJ

The error during initialization is a 'DSO (Define Subsystem Operation x'F7') which Hercules does not support.

The error at the time of the failure was a 'Unit Check/No Record Found'.

 
Then, on Sat 12/25/2021 12:50 PM, he wrote in a offline email to someone else which he forwarded a copy to me as an FYI courtesy:

This is based on the latest DS8xxx manuals that IBM only distribues to other hardware vendors for a fee. Each page has the vendor's name watermarked, so if it leaks they know who did it.

DSO is very similar to PSF (Perform Subsystem Function x'27'). New orders and suborders are only added to DSO and PSF is a thing of the past.

Looks like z/OS is issuing order 'Prepare for Read Subsystem Data (x'18'), suborder 'Read Feature Codes x'41'.

DSO also speeds up IPL process when thousands of devices are involved, as it penetrates a reserve.

If I was in Hercules development, I would treat DSO the same as a PSF, because most older orders are the same format.

 
This GitHub Issue is being created to formally document the above so we don't lose track of it, and in the hope that some day, one of us will have the time to try and implement the above suggested handling of the missing CCW opcode X'F7' support.

[salva-rczero]

I can confirm z/OS 2.5 ICKDSF Init vol utility, al use a F7 cmd associated with a 3E:

CCW CHAIN         FORMAT 1          IO                DEV..... 01C12    ASCB.... 00FB5E80 CPU..... 0
04ACAD80 F760000C 37DEBF58 18000000 00004100 00000000                                              |
04ACAD88 3E200100 37DEBDF8 00070009 000D0011 DDFFFDE5 E679BFD5 FFE00000 00000000 FFDCFFBE F7A00000 |
                           F7B7FFD2 80000000 AED00000 00000000 0059000D 00070000 F6DFFF80 00000000 |

[Fish-Git]

Closed by commit a047205.