IBM: BELBK

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.

BELBK

Prolog

Control Block Contents

BELBK DSECT

Storage Layout

Cross Reference (Contains links to field and bit definitions)

BELBK Prolog

 NAME       : HCPBELBK
 DESCRIPTION: Block I/O entry list
 DSECT      : BELBK
 FUNCTION   : This DSECT maps the input parameter list sent
              by the guest to CP when the guest requests
              an I/O operation via DIAGNOSE X'250'.
 LOCATED BY : BRQBELBK in the BRQBK
 CREATED BY : HCPBIDRW (who copies the guest's parameter
              list into host storage)
 DELETED BY : HCPBIDRW, for synchronous requests
              HCPBIDRW. for asynchronous requests
              satisfied synchronously
              HCPBIRIN, for asynchronous requests
              satisfied asynchronously
 SERIALIZED : Instruction stream serialization
 COMMENTS   :
              This parameter list may not be word-aligned in
              guest storage. However, this DSECT assumes that
              before any fields are referenced, the parameter
              list has been moved into host storage and
              word-aligned. References to fields in this block
              will cause an exception if this is not the case.
              There is one entry within the block I/O entry list
              for each read/write request.
              This control block is a GPI, and should
              not be changed incompatibly.

BELBK Control Block Content


BELBK DSECT
Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      BELBK          Block I/O entry list
0000    0 Signed       4 * (0)
0000    0 Bitstring    1 BELRQTYP       Type of operation being
                                        .requested.
          00000001       BELWRITE       X'01' Write operation requested
          00000002       BELREAD        X'02' Read operation requested
0001    1 Bitstring    1 BELSTAT        Status code for this operation
          00000000       BELOK          X'00' The read or write operation
                                        was successful
          00000001       BELINVBK       X'01' Invalid block number
                                        specified
          00000002       BELADDRE       X'02' Addressing exception
                                        condition
          00000003       BELRODEV       X'03' A write operation was
                                        requested to a read-only device
          00000004       BELINVSZ       X'04' Block size does not match
                                        that of the virtual device
          00000005       BELIOERR       X'05' Unrecoverable I/O error
          00000006       BELBADRQ       X'06' Request type is not read or
                                        write
          00000007       BELPROTE       X'07' Protection exception
                                        condition
          00000008       BELADCPE       X'08' Addressing-capability
                                        exception condition
          00000009       BELALTRE       X'09' ALEN-translation exception
                                        condition
          0000000A       BELALSPE       X'0A' ALET-specification
                                        exception condition
          0000000B       BELSPECE       X'0B' Specification exception
                                        condition
          0000000C       BELNOTPR       X'0C' This block I/O entry was
                                        not processed
0002    2 Bitstring    2 BELRSD01       Reserved for IBM use
0004    4 Signed       4 BELBKNUM       Block number
0008    8 Address      4 BELBALET       ALET of guest data buffer
000C   12 Address      4 BELBUFAD       Address of guest data buffer
                                        .(guest absolute address)
0010   16 Signed       4 BELNEXT (0)    Start of next entry in p-list
          00000002       BELSIZE        (*-BELBK+7)/8 Size of one entry
                                        of the .BELBK in doublewords

BELBK Storage Layout

*** BELBK - Block I/O entry list
*
*     +------+------+-------------+---------------------------+
*   0 |:RQTYP|:STAT |  BELRSD01   |         BELBKNUM          |
*     +------+------+-------------+---------------------------+
*   8 |         BELBALET          |         BELBUFAD          |
*     +---------------------------+---------------------------+
*  10 |                                                       |
*     =                       BELNEXT                         =
*     |                                                       |
*     +-------------------------------------------------------+
*
*** BELBK - Block I/O entry list