XLDBK

Prolog  

Control Block Contents  
   XLDBK DSECT
   XLDENTRY DSECT

Storage Layout  

Cross Reference (Contains links to field and bit definitions)  

XLDBK Prolog

 NAME       : HCPXLDBK
 DESCRIPTION: eXtent List Definition BlocK.
 DSECT      : XLDBK
 FUNCTION   : The XLDBK is used for parameter passing for
              diagnose X'244'.
 LOCATED BY : Rx      - Diagnose X'244' Rx register.
 CREATED BY : Created in the guest virtual machine's storage and
              copied into a buffer page for CP use.
 DELETED BY : Deleted by the guest virtual machine.
 SERIALIZED : Guest Virtual Machine is responsible.
 RELOCATION CONSIDERATIONS : None
 COMMENTS   : This is a variable size block.
              Use the following formula to figure out the actual
              size of the control block.
              XLDSIZE+(((nnn(XLDENTSZ))+7)/8)= number of doublewords
              Where: XLDSIZE  - Header size in doublewords.
              nnn      - Number of contiguous extent entries.
              XLDENTSZ - Total size in bytes of one extent
              entry.

XLDBK Control Block Content

XLDBK DSECT

Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      XLDBK          eXtent List Definition BlocK.
0000    0 Signed       4 XLDALET        ALET specifying the ad- dress
                                        space in which the next XLDBK
                                        resides.
0004    4 Signed       4 XLDFWDPT       Forward pointer to next XLDBK.
0008    8 Signed       4 XLDENTCT       Count of entries to be processed.
000C   12 Signed       4 XLDRSVD        Reserved for IBM use. This field
                                        must contain zeroes.
0010   16 Signed       4 XLDENTR1 (0)   Use XLDENTRY to map the entries
                                        that follow.
             The following are used to determine the size of the
      header for this control block.                            .
          00000010       XLDLEN         *-XLDBK Length of the header in
                                        bytes.
          00000002       XLDSIZE        (XLDLEN+7)/8 Size of the header
                                        in doublewords.
             The following DSECT represents an extent entry.

XLDENTRY DSECT

Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      XLDENTRY       eXtent List Definition BlocK.
0000    0 Signed       4 XLDPRBN        This is the pool- relative block
                                        number assigned to the block
                                        specified for XLDMRBN.
0004    4 Signed       4 XLDMRBN        Relative-block number of record
                                        on minidisk. Referenced from the
                                        start of the virtual minidisk
                                        starting with zero (0).
0008    8 Signed       4 XLDCOUNT       Number of relative- block
                                        numbers(RBNs) for this extent.
000C   12 Signed       2 XLDDEVNM       Virtual device number of device
                                        to be mapped.
000E   14 Signed       2 *              Reserved for IBM use.
          00000010       XLDETLEN       *-XLDENTRY Length of the 1st
                                        entry.
          00000002       XLDESIZE       (XLDETLEN+7)/8 Size of this
                                        control block in doublewords.
0010   16 Signed       4 XLDNXTET (0)   Next extent in list.
          00000100       XLDNMETP       4096/XLDETLEN The number of
                                        entries contained in a page.
          00001000       XLDSZETP       XLDETLEN*XLDNMETP Total storage
                                        size of all entries that can fit
                                        into a page.

XLDBK Storage Layout

          
*** XLDBK - eXtent List Definition BlocK.
*
*     +---------------------------+---------------------------+
*   0 |         XLDALET           |         XLDFWDPT          |
*     +---------------------------+---------------------------+
*   8 |         XLDENTCT          |         XLDRSVD           |
*     +---------------------------+---------------------------+
*
*** XLDBK - eXtent List Definition BlocK.
          
*** XLDENTRY - eXtent List Definition BlocK.
*
*     +---------------------------+---------------------------+
*   0 |         XLDPRBN           |         XLDMRBN           |
*     +---------------------------+-------------+-------------+
*   8 |         XLDCOUNT          |  XLDDEVNM   |/////////////|
*     +---------------------------+-------------+-------------+
*
*** XLDENTRY - eXtent List Definition BlocK.

XLDBK Cross Reference

Symbol         Dspl Value
-------------- ---- -----
XLDALET        0000
XLDCOUNT       0008
XLDDEVNM       000C
XLDENTCT       0008
XLDENTR1       0010
XLDESIZE       000E 00000002
XLDETLEN       000E 00000010
XLDFWDPT       0004
XLDLEN         0010 00000010
XLDMRBN        0004
XLDNMETP       0010 00000100
XLDNXTET       0010
XLDPRBN        0000
XLDRSVD        000C
XLDSIZE        0010 00000002
XLDSZETP       0010 00001000