IBM: CHCBK

Programming Interface Information: This information is NOT intended to be
used as Programming Interfaces of VM/ESA. It is to be used for diagnosis only.

CHCBK

Prolog

Control Block Contents

CHCBK DSECT

Storage Layout

Cross Reference (Contains links to field and bit definitions)

CHCBK Prolog

 NAME       : HCPCHCBK
 DESCRIPTION: CHANNEL CLASS BLOCK
 DSECT      : CHCBK
 FUNCTION   : DESCRIBE THE STATUS OF THE CHANNELS ( IN XA MODE, THE
              CHANNEL CLASSES) FOR A VIRTUAL MACHINE.
              ANCHOR THE QUEUE OF DEVICES (FOR EACH CHANNEL NUMBER OR
              CLASS) FOR WHICH INTERRUPTS ARE PENDING.
 LOCATED BY : VMDCHC FIELD IN THE VIRTUAL MACHINE'S DEFINITION BLOCK
 CREATED BY : VIRTUAL MACHINE CREATION PROCESS - HCPBVM
 DELETED BY : VIRTUAL MACHINE DESTRUCTION PROCESS

CHCBK Control Block Content


CHCBK DSECT
Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      CHCBK          CHANNEL CLASS BLOCK
0000    0 Dbl-Word     8 CHCLOCK (0)    LOCKWORD FOR THIS BLOCK
0000    0 Address      4 CHCLOWNR       ADDRESS OF OWNING VMDBK
0004    4 Address      4 CHCLOCWQ       QUEUE OF WAITING TASKS
0008    8 Dbl-Word     8 CHCSCHMD (0)   SET-CHANNEL-MONITOR DOUBLEWORD
                                        THE FOLLOWING FIELDS CONTROL
                                        GUEST CHANNEL MONITORING. THEY
                                        ARE KEPT WITHIN A DOUBLEWORD TO
                                        ALLOW A STORE-MULTIPLE TO PERFORM
                                        MP-CONSISTENT SETTING OF THE
                                        CONTROLS ON A HOST MP.
0008    8 Bitstring    1 CHCKEY         KEY OF USER MEASUREMENT BLOCK
0009    9 Bitstring    1 *              RESERVED FOR FUTURE IBM USE
000A   10 Bitstring    1 *              RESERVED FOR FUTURE IBM USE
000B   11 Bitstring    1 CHCHFLAG       HARDWARE CONTROLS
          .... ..1.      CHCMSM         X'02' MEASUREMENT ACTIVE
          .... ...1      CHCTIM         X'01' TIMING (SHOULD BE) ACTIVE
000C   12 Signed       4 CHCMBLKO       MEASUREMENT BLOCK INDEX
0010   16 Signed       4 CHCIORW        POINTER TO CHAIN OF CRWBK'S.
0014   20 Bitstring    1 CHCSFLAG       SOFTWARE CONTROLS
          1... ....      CHCRWCC1       X'80' CONDITION CODE 1 REMAINS TO
                                        BE GIVEN TO A GUEST STORE CHANNEL
                                        REPORT WORD SINCE GENERATING A
                                        MACHINE CHECK FOR A PREVIOUS
                                        CHANNEL REPORT WORD CONDITION.
                                        THIS BIT IS CLEARED BY AN I/O
                                        SYSTEM RESET. IT PREVENTS THE
                                        GENERATION OF A MACHINE CHECK FOR
                                        CHANNEL REPORT WORDS MADE
                                        PENDING.
0015   21 Bitstring    1 *              RESERVED FOR FUTURE IBM USE
0016   22 Bitstring    1 *              RESERVED FOR FUTURE IBM USE
0017   23 Bitstring    1 *              RESERVED FOR FUTURE IBM USE
0018   24 Signed       4 CHCSALIM       SET ADDRESS LIMIT VALUE
001C   28 Signed       4 CHCMCV         POINTER TO MCVBK. FOR FLOATING
                                        MACHINE CHECKS (THEY ARE RELATED
                                        TO THE I/O SUBSYSTEM).
0020   32 Signed       4 *              RESERVED FOR FUTURE IBM USE
0024   36 Signed       4 *              RESERVED FOR FUTURE IBM USE
0028   40 Signed       4 *              RESERVED FOR FUTURE IBM USE
002C   44 Signed       4 CHCIOPND       MASK OF PENDING INTERRUPTIONS
0030   48 Dbl-Word     8 CHCQUEUE (32)  FWD AND BWD INTERRUPT PTRS
          00000020       CHCQSIZE       (*-CHCQUEUE)/CHCQENTL DEFINE
                                        NUMBER OF CHANNELS
          00000026       CHCSIZE        (*-CHCBK+7)/8 SIZE OF FLOATING
                                        CHANNEL BLOCK
0030   48 Signed       4 CHCQUEFW       CHANNEL INT. QUEUE FORWARD PTR
0034   52 Signed       4 CHCQUEBW       CHANNEL INT. QUEUE BACKWARD PTR
          00000008       CHCQENTL       *-CHCQUEFW LENGTH OF QUEUE
                                        POINTERS

CHCBK Storage Layout

*** CHCBK - CHANNEL CLASS BLOCK
*
*     +---------------------------+---------------------------+
*   0 |         CHCLOWNR          |         CHCLOCWQ          |
*     +------+------+------+------+---------------------------+
*   8 |CHCKEY|//////|//////|:HFLAG|         CHCMBLKO          |
*     +------+------+------+------+------+------+------+------+
*  10 |         CHCIORW           |:SFLAG|//////|//////|//////|
*     +---------------------------+------+------+------+------+
*  18 |         CHCSALIM          |          CHCMCV           |
*     +---------------------------+---------------------------+
*  20 |///////////////////////////|///////////////////////////|
*     +---------------------------+---------------------------+
*  28 |///////////////////////////|         CHCIOPND          |
*     +---------------------------+---------------------------+
*  30 |                                                       |
*     =                       CHCQUEUE                        =
*     |                                                       |
*     +-------------------------------------------------------+
* 130
*
*** CHCBK - CHANNEL CLASS BLOCK
*** Overlay for CHCQUEUE in CHCBK
*
*     +---------------------------+---------------------------+
*  30 |         CHCQUEFW          |         CHCQUEBW          |
*     +---------------------------+---------------------------+
*  38
*
*** Overlay for CHCQUEUE in CHCBK