Type ASSEMBLE
Source Lines : 366
Fixes Applied : 8
Most Recent Version : Thursday, December 7, 1978
Last Fix ID : [R13292DK]

Module

       DMKGIO

Function

       TO ALLOW CP TO DO ERROR RECOVERY FOR I/O OPERATIONS THAT
       WERE INITIATED BY CMS.

Attributes

       REENTRANT, PAGEABLE, CALLED VIA SVC

Operation

       DMKGIO IS CALLED BY DMKHVC WHEN A USER HAS ISSUED A
       HYPERVISOR CALL FOR TAPE, UNIT RECORD, OR NON-STANDARD
       DISK I/O CHANNEL PROGRAMS. A CHECK IS MADE TO VALIDATE THAT
       THE DEVICE ADDRESS IS CORRECT AND, FOR MINIDISKS, THAT
       THE DEVICE IS NOT RESERVED BY ANOTHER USER.  IF NO ERROR
       IS DETECTED, DMKGIO
       BUILDS AN IOBLOK AND CALLS DMKCCWTR. ON RETURN FROM DMKCCWTR
       A CALL IS MADE TO DMKIOSQV TO SCHEDULE A VIRTUAL DEVICE
       REQUEST. WHEN THE I/O OPERATION COMPLETES DMKGIO REGAINS
       CONTROL AT LABEL "DIAGRTN". THE IOBLOK IS CHECK FOR AN ERROR
       CONDITION AND IF NONE EXISTS,THE IOBLOK IS FRETTED, THE
       CONDITION CODE IS SET AND RETURN IS TO DMKDSPCH.

       OTHERWISE DMKUNTRN IS CALLED TO CONVERT THE REAL CSW TO A
       VIRTUAL CSW. THE USER'S PAGE 0 IS THEN READ IN AND THE
       CSW MOVE INTO IT. A RETURN CODE IS LOADED INTO REG.15
       AND THE PSW "CONDITION CODE" IS SET. FREE STORAGE IS
       RETURNED TO THE SYSTEMS POOL AND RETURN IS MADE TO DMKDSPCH.

Calls to Other Routines

       DMKFREE    USED TO OBTAIN STORAGE FOR BUILDING IOBLOK.
       DMKFRET    USED TO RETURN STORGE FOR IOBLOK.
       DMKIOSQV   TO QUE THE I/O REQUEST.
       DMKCCWTR   TO BUILD A REAL CHANNEL PROG. FROM VIRTUAL CCW'S.
       DMKDSPCH   TO ALLOW OTHER ROUTINES TO RUN.
       DMKUNTRN   TO TRANSLATE THE REAL CSW TO A VIRTUAL CSW.
       DMKUNTFR   TO FREE STORAGE USED FOR BUILDING REAL CCW'S.
       DMKSCNVU - TO LOCATE A VIRTUAL DEVICE
       DMKSCNVD - TO GET THE DEVICE ADDRESS IN CCU FORM