Programming Interface Information: This information is NOT intended to be used as Programming Interfaces of z/VM.

#### HALBK

Prolog

Control Block Contents
HALBK DSECT

Storage Layout

Cross Reference (Contains links to field and bit definitions)

#### HALBK Prolog

     NAME       : HCPHALBK
     DESCRIPTION: Host-ART lookaside block
     DSECT      : HALBK
     FUNCTION   : The HALBK maps ALETs to I-ASITs for
                  host-access-register translation.
     SERIALIZED : Each task is responsible for its own
                  serialization
     COMMENTS   : This block is meant to be used with the
                  HCPHALM macro. The user must:
                  - acquire HALBK storage
                  - have an active HCPUSING on the block
                  - fill in the header.
                  Then HCPHALM may be used to search and
                  manipulate entries in this block.
                  The count of the number of entries in the HALBK
                  must fit in a fullword; that's the only
                  restriction on HALBK size. If, however, the
                  total size of the HALBK (header + (entry length
                  * number of entries)) could be greater than
                  509 doublewords, the PAGES=DECIDE option should
                  be used on the HCPGETST and HCPRELST macros.

#### HALBK Control Block Content

#### HALBK DSECT

    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      HALBK          Host-ART lookaside block
    0000    0 Character   16 HALHDR         HALBK header
    0010   16 Character   16 HALENTRY       HALBK entry (there can be more
                                            than one of these).
          Mapping of the HALBK header
    0000    0 Signed       4 HALMXENT       Maximum number of HALBK entries
    0004    4 Address      4 HALVMDBK       Address of the base VMDBK
                                            associated with the access list
                                            to which the ALETs belong.
    0008    8 Character    8 *              Reserved for IBM use.
          Mapping of HALBK entries
    0010   16 Bitstring    1 HALSTATE       State flag for the entry
              00000000       HALINVAL       X'00' HALINVAL The entry is
                                            invalid (does not contain an
                                            ALET/i-ASIT pair).
              00000001       HALVALID       X'01' HALVALID The entry is valid
                                            (does contain an ALET/i-ASIT
                                            pair).
    0011   17 Bitstring    3 *              Reserved for IBM use
    0014   20 Signed       4 HALALET        ALET
    0018   24 Character    8 HALIASIT       I-ASIT associated with HALALET
    0020   32 Signed       4 HALNEXT (0)    Next entry in the list
          Length equate
              00000004       HALSIZE        (*-HALBK+7)/8 Length of HALBK in
                                            DWs

#### HALBK Storage Layout

    *** HALBK - Host-ART lookaside block
    *
    *     +-------------------------------------------------------+
    *   0 |                        HALHDR                         |
    *     |                                                       |
    *     +-------------------------------------------------------+
    *  10 |                       HALENTRY                        |
    *     |                                                       |
    *     +-------------------------------------------------------+
    *  20
    *
    *** HALBK - Host-ART lookaside block

    *** Overlay for HALHDR in HALBK
    *
    *     +---------------------------+---------------------------+
    *   0 |         HALMXENT          |         HALVMDBK          |
    *     +---------------------------+---------------------------+
    *   8 |///////////////////////////////////////////////////////|
    *     +-------------------------------------------------------+
    *  10
    *
    *** Overlay for HALHDR in HALBK

    *** Overlay for HALENTRY in HALBK
    *
    *     +------+--------------------+---------------------------+
    *  10 |:STATE|////////////////////|         HALALET           |
    *     +------+--------------------+---------------------------+
    *  18 |                       HALIASIT                        |
    *     +-------------------------------------------------------+
    *
    *** Overlay for HALENTRY in HALBK

#### HALBK Cross Reference

    Symbol         Dspl Value
    -------------- ---- -----
    HALALET        0014
    HALENTRY       0010
    HALHDR         0000
    HALIASIT       0018
    HALINVAL       0010 00000000
    HALMXENT       0000
    HALNEXT        0020
    HALSIZE        0020 00000004
    HALSTATE       0010
    HALVALID       0010 00000001
    HALVMDBK       0004

This information is based on z/VM V6R1.0. Last updated on 18 Feb 2010 at 08:43:01 EDT.
Copyright IBM Corporation, 1990, 2008