Inter-User Communications Vehicle ••••.•••.•••..•..•••..•.•••.•••..•..•••••••••.•.•• 110 IUCV Paths ................................................................. 110 IUCV Messages .............................................................. 111
Message Queues ............................................................. 111
Message Data Transfer ........................................................ 112
Message Identification ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 113
Pending IUCV Communications ................................................. 114
CP Communications .......................................................... 116 Second Level Support ......................................................... 117
Trace Table Entries ........................................................... 117
Audit Trail .................................................................. 118
Restrictions ................................................................. 118
Security Considerations ........................................................ 118
Performance Considerations .................................................... 119 Using IUCV Functions ........................................................... 119 IUCV Communications Using Parameter List Data .................................. 125
Invoking IUCV Functions ...................................................... 126
Invoking Communications between CP and a Virtual Machine .......................... 140
Requests Initiated by the Virtual Machine .......................................... 140
CP Initiated Requests ......................................................... 141 IUCV Parameter List Formats ..................................................... 142 IUCV External Interrupt Formats .................................................. 159 IUCV Trace Table Entry Formats .................................................. 173
Trace Table Entry Field Definitions .............................................. 174 SNA Virtual Console Communication Services .•..••.•••••••.•••••••••..••..••.••.•••..• 177 System Structure ................................................................ 177
Environments Supported .......................................................... 179
Frocessing Descriptions .......................................................... 179 SNA CCS Entries in CP Internal Trace Table ......................................... 187
Trace Table Entry Formats ..................................................... 187
Trace Table. Entry Field Definitions .............................................. 189
The Message System Service ...•.....•....•..•...•..••...••..•.•...•..••..•..•..•.. 192
Establishing Communications ...................................................... 192
DASD Block I/O System Service •••....•..••••..••.•••..•••.•••..••..••.••..•..••.• 194
Establishing Communications with DASD Block I/O Service ............................. 194 IUCV CONNECT to the DASD Block I/O System Service ............................ 194 IUCV SEND to the DASD Block I/O System Service ................................ 196
The Special Message Facility ..•..•••••.••.••.••..••••.•..•••.•••.•••.••..••..••.•.. 198
Single Console Image Facility •••.••••.....••••••••.•••.•••.••••.•••.••••••..•...•.•• 200
Using the Single Console Image Facility .............................................. 200
VM/SP Use of the IBM 3850 MSS ••.••.••.••••••.••••.•..••••.••.•••.••.••••••.••. 201 VM/SP Access to the MASS Storage Control ......................................... 201
Asynchronous MSS Mount Processing ............................................... 201 VM/SP Processing of MSS Cylinder Faults ........................................... 202
Backup and of MSS Volumes .............................................. 202
Logical Device Support Facility ••.•••.••.••.•••.•••.••...••••••.••••••••••.••.••.••• 203
Timers in a Virtual Machine •••••••.••.••••••••••••••••••••••••••.•••••••••••••.•••. 205
Interval Timer .................................................................. 205
Processor Timer ................................................................ 206 TOD Clock .................................................................... 206
Clock Comparator .............................................................. 206
Pseudo Timer .................................................................. 207
Pseudo Timer Start I/O ........................................................ 207
Pseudo Timer DIAGNOSE ..................................................... 207
CP in Attached Processor and Multiprocessor Modes •.••.••..••••••••..•••.•••••••.•••.•• 208
Multiprocessor Environment ........................................................ 208
Attached Processor Environment ................................................... 208
Advantages of the AP /MP Environment ............................................. 209
Contents xvii

Facilitating an AP /MP Environment ................................................ 209 Prefixing ......... .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209 Identifying a Processor Address ................................................. 210 Signaling ................................................................... 211
Time-of-Day (TOD) Clock Synchronization Check .................................. 213
Fetching and Storing .......................................................... 213
Locks and Serialization of Functions .............................................. 214
Affinity .................................................................... 218 Shared Segments in an AP /MP Environment ....................................... 218 SWTCHVM Macro .. , ........................................................ 219
Configuring and Debugging MP Systems ............................................. 219
Configuring I/O Devices for an MP System ........................................ 219
Debugging an AP /MP System ................................................... 220 DIAGNOSE Instruction in a Virtual Machine •..•••.•••••.•••.•••••••••••••••••••••••••• 222 DIAGNOSE Code X'OO' -- Store Extended-Identification Code ........................... 222 DIAGNOSE Code X'04' --Examine Real Storage ...................................... 224 DIAGNOSE Code X'08' --Virtual Console Function ................................... 225 DIAGNOSE Code X'OC' -- Pseudo Timer ............................................ 227 DIAGNOSE Code X'10' --Release Pages ............................................ 228 DIAGNOSE Code X'14' --Input Spool File Manipulation ................................ 228 Subcode X'OOOO' ............................................................. 229 Subcode X'0004' ............................................................ 229 Subcode X'0008' ............................................................ 230 Subcode X'OOOC' ............................................................ 230 Subcode X'0010' ............................................................. 230 Subcode X'0014' ............................................................ 230 Subcode X'0018' ............................................................ 231 Subcode X'OOlC' ............................................................ 231 Subcode X'0020' ............................................................ 231 Subcode X'0024' ............................................................ 231 Subcode X'OFFE' ............................................................ 231 Subcode X'OFFF' .............................................................. 232 DIAGNOSE Code X'18' -- Standard DASD I/O ....................................... 232 DIAGNOSE Code X'lC' --Clear Error Recording Cylinders ............................. 235 DIAGNOSE Code X'20' --General I/O ............................................. 235 DIAGNOSE Code X'24' --Device Type and Features ................................... 236 DIAGNOSE Code X'28' --Channel Program Modification ............................... 239 DIAGNOSE Code X'2C' --Return DASD Start of LOGREC ............................. 240 DIAGNOSE Code X'30' --Read One Page of LOGREC Data ............................ 241 DIAGNOSE Code X'34' --Read System Dump Spool File ............................... 241 DIAGNOSE Code X'38' --Read System Symbol Table .................................. 242 DIAGNOSE Code X'3C' -- VM/SP Directory ........................................ 242
Diagnose Code X'40' -- Clean-Up after Virtual IPL by Device ............................ 243 DIAGNOSE Code X'48' --Issue SVC 76 from a Second Level VM/370 or VM/SP Virtual
Machine ..................................................................... 243 DIAGNOSE Code X'4C' --Generate Accounting Records for the Virtual User ............... 243 DIAGNOSE Code X'50' -- Save the 370X Control Program Image ........................ 245 DIAGNOSE Code X'54' --Control The Function of the PA2 Function Key .... , ............. 246 DIAGNOSE Code X'58' -- 3270 Virtual Console Interface ............................... 246
Displaying Data .............................................................. 247
Full Screen Mode ............................................................ 248 DIAGNOSE Code X'5C' --Error Message Editing ..................................... 253 DIAGNOSE Code X'60' -Determining the Virtual Machine Storage Size .................... 253 DIAGNOSE Code X'64' -Finding, Loading, and Purging a Named Segment ................. 253 DIAGNOSE Code X'68' --Virtual Machine Communication Facility (VMCF) ............... 256 DIAGNOSE Code X'6C' -- Special Diagnose for Shadow Table Maintenance ................ 257 DIAGNOSE Code X'70' --Activating the Time-of-Day (TOD) Clock Accounting Interface ..... 257 DIAGNOSE Code X'74' -- Saving or Loading a 3800 Named System ....................... 258 DIAGNOSE Code X'78' -- MSS Communication ...................................... 259 DIAGNOSE Code X'7C' --Logical Device Support Facility .............................. 260 Descriptions of Logical Device Support Facility Sub functions ........................... 262
External Interrupt Code X'2402' ................................................ 264
Logical Device Restrictions ..................................................... 264 DIAGNOSE Code X'80' -- MSSFCALL ............................................. 265 MSSF COMMAND WORDS .................................................... 265 DIAGNOSE Code X'84' --Directory Update-In-Place .................................. 267 DIAGNOSE Code X'8C' --Access Certain Device Dependent Information .................. 274
xviii VM/SP System Programmer's Guide