GENERAL I/O OPERATION INITIATED VIA DIAGNOSE DMKGIOEX ---Perform general I/O operation. Entry is via DMKHVC code 20. DMKSCNVU ---Pind-device related to SIO cuu address. DMKFREE Allocate storage for the IOBLOK. DMKCCWTR ----Buila the read CCW list. Queue the I/O request for execution. DMKGIO, DIAGRTN ---On-interruption return, check status. If no proDiem encountered, free storage used for ccw string and IOBLOK. DMKGIO, DIAGRTN ---aeflect-the-condition code and return code to the user. DMKDSPCH dispatcher. DMKUNTRN ---on-returned error condition, convert real CSi to virtual CSi and set
in user's page O. DMKGIO, Exit via SVC 12. VIRTUAL MACHINE I/O INSTRUCTION SIMULATION AND INTERRUPTION REFLECTION DMKVSIEX -- Entry from DMKPRV to simulate I/O per VMBLOK's VMINST field. On detected SIO, call - DMKSCNVU ---ro-Iocate VCHBLOK, VCUBLOK, and VDEVBLOK for the cuu called per SIO instructione DMKVSIEX ---netermine device availability and set condition code accordingly. If the operation is warranted, schedule the operation. For TIO, check device status, pending interrupts, and set appropriate
condition codes. VIO.!!!Q For BIO, check for dedicated channel, CE, CU, or device busy
condition, and subchannel busy and set appropriate condition codes. Check for dedicated selector or busy channel and check for pending
abnor.al interruption and set appropriate condition code. CP Method of Operation and program Organization 1-191

Ql!KVIQ'!! Entry from DMKDSP to process the reflected virtual interruption. Dl!KSCNVU the VCHBLOK, VCUBLOK, and VDEVBLOK. DMKVIOIN -- Analyze blocks and reflect condition code to user. If condition code equals 1 (cc=1), save status from the real device (if real device)
and DMKUNTFR. D!!KUNTFR and store CSi in user's page O. On T IO or BIO, free the device and set CC=1.
DMKFRET ---Pret storage for the IOBLOK. DMKDSPCH dispatcher. VIRTUAL CONSOLE SIMULATION DMKVSIEX for virtual console activity comes from the SCP stored in the
user's virtual machine. The program's generated CCws and data are
reflected to the attached terminal used by the virtual machine operator. DMKVCNEX ---rocate and .ove non-TIC CCis from the users virtual storage to a VCONCTL block. Update CAi and CSi in respective control block. DMKVCN, VCNRD ---Per read-operation, build a read console buffer VCONBUF for the input
to be read from the terminal. Queue a console read request. DMKVCNEX ---Set-return address in VCONCTL VCNRDRET field. DMKVSPVP Spool console activity if SPOOL CONSOLE START specified. DMKDSPCH - Exit-to dispatcher. iait for completion. DMKVCN, VCNiR Calculate and obtain free storage (VCONBUF) necessary for the write
to console operation. Translate and bring in user's data page and move it into VCONBUF. 12MKQ£!iiT Queue a console write request. DMKDSPCH dispatcher. ON a sense operation, set CE and DE PCI flag in the PSi if the PCI flag
flag if warranted. Move the sense
storage as designated by the CCW. reflect status and count.
in the virtual PSi. Reflect the was set in the CCW •. Set the IL
data from the VDEVBLOK to user Update VDEVBLOK's VDEVCSW to
1-192 IBM VM/370 System Logic and Problem Determination--Volu.e 1