RCPTE

Prolog  

Control Block Contents  
   RCPTE DSECT

Storage Layout  

Cross Reference (Contains links to field and bit definitions)  

RCPTE Prolog

 NAME       : HCPRCPTE
 DESCRIPTION: REFERENCE AND CHANGE PRESERVATION TABLE ENTRY
 DSECT      : RCPTE
 FUNCTION   : A REFERENCE AND CHANGE PRESERVATION TABLE ENTRY
              IS USED TO KEEP TRACK OF THE REFERENCE AND
              CHANGE BITS FOR A 4K PAGE OF VIRTUAL STORAGE.
 LOCATED BY : THERE ARE NO POINTERS TO RCP TABLE ENTRIES IN THE
              SYSTEM. THESE ENTRIES MAY RESIDE IN ONE OF THREE
              PLACES:
              1) A RESIDENT RCP PAGE (MAPPED THROUGH THE HOST
              VIRTUAL ADDRESS SPACE),
              2) THE RCP BACKUP AREA IN THE PGMBK, OR
              3) THE PGSTES CORRESPONDING TO THE PAGES THE RCP
              DATA REPRESENTS.
 CREATED BY :
              IF THE STORAGE KEY ASSIST IS NOT BEING UTILIZED:
              HCPPTRCP - RCP PAGES ARE BUILT WHEN SIE PAGE FAULTS
              ON AN RCP PAGE.
              HCPRCIRS - MOVES RCP DATA FROM THE RCP PAGE TO THE
              RCP BACKUP AREA.
              IF THE STORAGE KEY ASSIST IS BEING UTILIZED:
              HCPBPBCU - CREATES A PGMBK AND THEREFORE PGSTES THAT
              WILL CONTAIN RCPTES.
 DELETED BY : HCPRPBPA - THE RCP AREA IS CLEARED WHEN THE VIRTUAL STORAGE
              IS RESET. AN RCP PAGE MAY BE STOLEN BUT THE ACTUAL
              RCP TABLE WILL EXIST UNTIL THE PGMBK IS RELEASED.
              WHEN AN RCP PAGE IS STOLEN, THE BYTES ARE BACKED
              UP IN THE CORRESPONDING PGMBKS BY HCPRCISA.
 COMMENTS   :
              - RCP DATA CORRESPONDING TO SYSTEM VIRTUAL PAGES
              WILL ALWAYS RESIDE IN THE PGSTES.
              - IF THE STORAGE KEY ASSIST IS BEING UTILIZED:
              - THE ARCHITECTURE DEFINES THE PGSRCP FIELDS
              AS THE LOCATION OF THE RCP DATA.
              - ALL RCP DATA IS SUSCEPTIBLE TO CHANGE BY THE
              STORAGE KEY ASSIST IF THE RCP INTERLOCK BIT IS
              NOT SET (RCP INTERLOCK BIT SERIALIZES CP AGAINST
              THE STORAGE KEY ASSIST AND VICE VERSA).
              - IF THE STORAGE KEY ASSIST IS NOT BEING UTILIZED
              - THE RCP AREA FOR A GUEST MACHINE CONTAINS ONE
              PAGE IN HOST VIRTUAL STORAGE FOR EACH 16 MEG OF
              GUEST STORAGE, STARTING AT THE HOST VIRTUAL
              ADDRESS CONTAINED IN 'VMDRCP'.  THE RCP PAGES
              ARE CONTAINED IN THE HOST ADDRESS SPACE USED
              TO DESCRIBE GUEST STORAGE, BUT THE RCP AREA
              IS NOT DIRECTLY ADDRESSABLE BY THE GUEST.
              - IF THE RCP AREA PAGE IS MARKED INVALID IN THE
              HOST PAGE TABLE, THE RCP BYTE APPEARS IN THE PAGE
              MANAGEMENT BLOCK (PGMBK) WHICH REPRESENTS THAT
              MEGABYTE OF GUEST STORAGE, STARTING AT PGMRCPTB.
              - ONLY THE RCP DATA RESIDING IN THE RCP PAGE IS
              SUSCEPTIBLE TO CHANGE BY THE SIE MICROCODE. IF
              THE RCP DATA RESIDES IN THE PGMBK, SIE WILL NOT
              BE ABLE TO CHANGE IT.
              - SHARED STORAGE RCP DATA IS ALWAYS KEPT IN THE
              RCP BACKUP AREA.

RCPTE Control Block Content

RCPTE DSECT

Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      RCPTE          REFERENCE AND CHANGE PRESERVATION
                                        TABLE ENTRY
     THIS CONTROL BLOCK DEFINES AN RCP BYTE (REFERENCE AND CHANGE
     PRESERVATION). THE FIELD IS DEFINED BY PROCESSOR ARCHITECTURE. DO NOT
     MODIFY THIS FIELD EXCEPT TO INSTALL ARCHITECTURE CHANGES.
0000    0 Bitstring    1 RCPBYTE        HARDWARE RCP BYTE FOR ONE 4K PAGE
          1... ....      RCPLOCK        X'80' RCP LOCK HELD
          .1.. ....      RCPHREF        X'40' HOST BACKUP REFERENCE BIT
          ..1. ....      RCPHCH         X'20' HOST BACKUP CHANGE BIT
          .11. ....      RCPHOST        RCPHREF+RCPHCH MASK FOR HOST BITS
          .... .1..      RCPGREF        X'04' GUEST BACKUP REFERENCE BIT
          .... ..1.      RCPGCH         X'02' GUEST BACKUP CHANGE BIT
          .... .11.      RCPGUEST       RCPGREF+RCPGCH MASK FOR GUEST
                                        BITS
     THE RCP (REFERENCE AND CHANGE PRESERVATION) AREA IS USED TO ALLOW THE
     HARDWARE REFERENCE AND CHANGE BITS FOR A SINGLE REAL PAGE TO RECORD
     REFERENCE AND CHANGE INFORMATION FOR USE BY BOTH THE GUEST AND BY THE
     HOST.
     WHENEVER THE HARDWARE EMULATES A GUEST SET STORAGE KEY (SSK)
     INSTRUCTION, THE OLD VALUE OF THE R/C BITS FROM THE REAL PAGE ARE OR'ED
     INTO THE HOST R/C BITS IN THE RCP AREA, THEN THE REAL R/C BITS ARE SET
     TO ZERO, AND THE NEW GUEST R/C BITS ARE PLACED IN THE RCP BYTE GUEST
     R/C BITS.
     WHEN THE HARDWARE EMULATES A GUEST RESET REFERENCE BIT (RRB)
     INSTRUCTION, THE CONDITION CODE IS DETERMINED FROM THE LOGICAL OR OF
     THE R/C BITS IN THE REAL PAGE WITH THE GUEST R/C BITS FROM THE RCP AREA
     BYTE FOR THAT PAGE. THE OLD VALUE OF THE REFERENCE BIT IN THE REAL PAGE
     IS OR'ED INTO THE HOST BACKUP REFERENCE BIT IN THE RCP AREA BYTE, AND
     THE REAL PAGE REFERENCE BIT PLUS THE GUEST BACKUP REFERENCE BIT IN THE
     RCP BYTE ARE SET TO ZERO.
     WHEN THE HARDWARE EMULATES A GUEST INSERT STORAGE KEY INSTRUCTION, THE
     GUEST IS GIVEN THE KEY FROM REAL STORAGE, PLUS THE R/C BITS FROM THE
     REAL PAGE OR'ED WITH THE GUEST BACKUP R/C BITS FROM THE RCP AREA BYTE
     FOR THAT PAGE.
     WHEN SOFTWARE MODIFIES THE R/C BITS IN REAL STORAGE WHICH REPRESENTS A
     GUEST PAGE, THE SOFTWARE WILL LOGICALLY OR THE R/C BITS FROM REAL
     STORAGE INTO THE GUEST BACKUP R/C BITS FOR THAT PAGE PRIOR TO MODIFYING
     THE REAL STORAGE R/C BITS.
     IN ORDER THAT ONLY ONE CPU IS ACCESSING A PARTICULAR RCP AREA BYTE AT A
     TIME (EITHER BY EMULATION HARDWARE OR BY SOFTWARE SIMULATION), A LOCK
     BIT IS DEFINED IN THE RCP AREA BYTE. PRIOR TO STARTING ANY OPERATION
     INVOLVING THE RCP AREA, A LOCK IS OBTAINED ON THE RCP AREA BYTE BY
     ATTEMPTING TO COMPARE-AND-SWAP THE LOCK BIT ON. IF THE HARDWARE
     EMULATION FACILITY IS UNABLE TO OBTAIN THE LOCK, THE INSTRUCTION WILL
     BE PRESENTED TO SOFTWARE AS AN INSTRUCTION INTERCEPTION.
0001    1 Bitstring    1 RCPNEXT (0)    NEXT RCP BYTE (ONLY TO BE USED IF
                                        THE STORAGE KEY ASSIST IS NOT
                                        BEING UTILIZED)

RCPTE Storage Layout

          
*** RCPTE - REFERENCE AND CHANGE PRESERVATION TABLE ENTRY
*
*     +------+
*   0 |:BYTE |
*     +------+
*
*** RCPTE - REFERENCE AND CHANGE PRESERVATION TABLE ENTRY

RCPTE Cross Reference

Symbol         Dspl Value
-------------- ---- -----
RCPBYTE        0000
RCPGCH         0000 02
RCPGREF        0000 04
RCPGUEST       0000 06
RCPHCH         0000 20
RCPHOST        0000 60
RCPHREF        0000 40
RCPLOCK        0000 80
RCPNEXT        0001