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Programming Interface Information:
This information is NOT intended to be used as Programming Interfaces of z/VM. |
PGS64
Control Block Contents
PGS64 DSECT
Cross Reference (Contains links to field and bit definitions)
PGS64 Control Block Content
PGS64 DSECT
Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure PGS64 PAGE STATUS TABLE ENTRY 0000 0 Dbl-Word 8 PGSGENTR Virtual Page Status Entry 0000 0 Signed 4 PGS64W0 Mirror of ESA/390 PGSTE 0004 4 Signed 4 PGS64W1 Reserved for IBM use 00000008 PGSGLENT *-PGSGENTR Length of one Status Table Entry 0008 8 Signed 4 PGSGNEXT (0) Next Page Status Table Entry 0000 0 Bitstring 1 PGSGVKEY Guest Storage key bits 0-4 1111 .... PGSVKACC X'F0' Access-control key value .... 1... PGSVKFET X'08' Fetch-protection control 1111 1... PGSVKACF PGSVKACC+PGSVKFET Acc-ctrl & fetch-prot bits 0001 1 Bitstring 1 PGSGRCP Architected area for RCP byte if storage key assist is being utilized, or the page belongs to the system. 1... .... PGSPCL X'80' Page Control Lock .1.. .... PGSRCPHR X'40' Host backup reference bit used for system pages ..1. .... PGSRCPHC X'20' Host backup change bit used for system pages .11. .... PGSHOST PGSRCPHR+PGSRCPHC Mask for host bits .... .1.. PGSGREF X'04' Guest backup reference bit .... ..1. PGSGCH X'02' Guest backup change bit .... .11. PGSGUEST PGSGREF+PGSGCH Mask for guest bits 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 PGSPCL is used for page serialization. This bit (and therefore page serialization) may only be obtained through the use of the page serialization macros. Note that the Page Control Lock and the RCP Interlock bit are one in the same if the Storage Key Assist is being utilized. The bits PGSERROR and PGSTRANS are modifiers to the Page Control Lock. The following table identifies the meaning of the state of the Page Control Lock and it's modifiers: PGSPCL PGSTRANS PGSERROR 0 0 0 Lock available 0 0 1 Invalid 0 1 0 Invalid 0 1 1 Invalid 1 0 0 Lock held for short period, spin or skip 1 0 1 Page in error, only 'release' can manipulate the page 1 1 0 Lock held for long period, skip or defer. Will be redriven when lock is made available 1 1 1 Invalid 0002 2 Bitstring 1 PGSGFLAG Virtual Page Flags 1... .... PGSINVAL X'80' No auxiliary storage assigned Notes : PGSINVAL, in combination with other PTE, PGSTE, and storage key status bits, is used by steal processing to identify first time reference pages of zeros which have never been re-referenced or changed and can simply be discarded. The "first time reference page of zeros" state is identified by the following bit combination: noformat PTE: PAGINVAL=0 (page is valid and resident) PGSTE: PGSINVAL=1 (no DASD slot assigned) PGSRCPHR=0 (unreferenced) PGSRCPHC=0 (unchanged) Real frame storage key: Reference=0 (unreferenced) Change =0 (unchanged) enoformat Any resident page in this state is assumed to be unchanged zeros, and therefore simply discardable by steal. No page with non-zero contents should ever be allowed to be in this state, or a lost page will eventually result. The host change bit, PGSRCPHC, should be used to indicate that a page which is unchanged, not already on DASD, and non-zero, must be eventually written to DASD. * Note that both reference bits (PGSRCPHR and the real storage frame reference bit) can "evaporate" to zero over time due to the action of the reorder function. Therefore, the fact that a frame has been referenced, or setting PGSRCPHR on, can not prevent a page from eventually entering this "first time reference page of zeros" state. .1.. .... PGSSHARE X'40' Page is a shared page ..1. .... PGS1READ X'20' ASA may be read only once. Used for shared pages. After the first read, this SDF (System Data File) ASA is to be ignored and the page left as changed. When the page is first written, it will go to a paging space ASA and this flag wil be turned off. PGS1READ on implies that page is read-only for the user. ...1 .... PGSALLOC X'10' Page in the system address space (or a system-owned utility address space) that is allocated, OR A shared CP page in the monitor DCSS that CP has translated and that has not yet been released by the user connected to the DCSS. When this bit is on: 1) The page is never part of a DASD block; 2) The associated PGMBK is never paged out. .... 1... PGSFIXED X'08' Storage slot permanently assigned .... .1.. PGSIO1ST X'04' Indicate the first page of PGMBK has completed I/O. Serialized via PGSTRANS. .... ..1. PGSIO2ND X'02' Indicate the second page of PGMBK has completed I/O. Serialized via PGSTRANS. .... .11. PGSIOFLG PGSIO1ST+PGSIO2ND 00000600 PGSIOMSK (PGSIO1ST+PGSIO2ND)*256 .... ...1 PGSREADO X'01' Storage slot (DASD) is read-only 0003 3 Bitstring 1 PGSGSTAT Virtual Page Status bits 1... .... PGSALTPT X'80' Page is defined in an alternate Page table pointed from PGMGALTP .1.. .... PGSTRANS X'40' Page is serialized in long term ..1. .... PGSPRBN X'20' ASA is, in fact, a PRBN ...1 .... PGSVMSLK X'10' Virtual machine storage lock mode .... 1... PGSXSTOR X'08' Page is in XSTORE .... .1.. PGSBLOCK X'04' This page is one page in a block of pages .... ..1. PGSRABI X'02' This page was read in as part of a block of pages. This bit can NOT be checked for PTRM pages, as it is redefined as PGSXSTMB in that case. .... ...1 PGSERROR X'01' Page is in error. A storage error was detected in this page and the page could not be recovered. When this bit is set, VMDRSSFG.VMDRSSUE must be set in the VMDBK that owns the space. 0003 3 Bitstring 1 PGSGPSTA Pageable PGMBK Virtual Page Status bits. .... ..1. PGSXSTMB X'02' This page (a pageable PGMBK) itself supports pages in XSTORE. This bit is only used for PTRM pages that currently reside in XSTORE (PGSXSTOR must also be on if PGSXSTMB is on). Note that this bit is a redefinition of the PGSRABI bit, which is acceptable since pageable PGMBKs (PTRM pages) are never blocked. .* .*
PGS64 Storage Layout
*** PGS64 - PAGE STATUS TABLE ENTRY
*
* +-------------------------------------------------------+
* 0 | PGSGENTR |
* +-------------------------------------------------------+
* 8
*
*** PGS64 - PAGE STATUS TABLE ENTRY
*** Overlay for PGSGENTR in PGS64
*
* +---------------------------+---------------------------+
* 0 | PGS64W0 | PGS64W1 |
* +---------------------------+---------------------------+
*
*** Overlay for PGSGENTR in PGS64
*** Overlay for PGS64W0 in PGS64
*
* +------+------+------+------+
* 0 |:GVKEY|:GRCP |:GFLAG|:GSTAT| 4
* +------+------+------+------+
*
*** Overlay for PGS64W0 in PGS64
*** Overlay for PGSGSTAT in PGS64
*
* +------+
* 0 ... 3 |:GPSTA| 4
* +------+
*
*** Overlay for PGSGSTAT in PGS64
PGS64 Cross Reference
Symbol Dspl Value -------------- ---- ----- PGSALLOC 0002 10 PGSALTPT 0003 80 PGSBLOCK 0003 04 PGSERROR 0003 01 PGSFIXED 0002 08 PGSGCH 0001 02 PGSGENTR 0000 PGSGFLAG 0002 PGSGLENT 0004 00000008 PGSGNEXT 0008 PGSGPSTA 0003 PGSGRCP 0001 PGSGREF 0001 04 PGSGSTAT 0003 PGSGUEST 0001 06 PGSGVKEY 0000 PGSHOST 0001 60 PGSINVAL 0002 80 PGSIOFLG 0002 06 PGSIOMSK 0002 00000600 PGSIO1ST 0002 04 PGSIO2ND 0002 02 PGSPCL 0001 80 PGSPRBN 0003 20 PGSRABI 0003 02 PGSRCPHC 0001 20 PGSRCPHR 0001 40 PGSREADO 0002 01 PGSSHARE 0002 40 PGSTRANS 0003 40 PGSVKACC 0000 F0 PGSVKACF 0000 F8 PGSVKFET 0000 08 PGSVMSLK 0003 10 PGSXSTMB 0003 02 PGSXSTOR 0003 08 PGS1READ 0002 20 PGS64W0 0000 PGS64W1 0004 RCPGCH 0001 02 RCPGREF 0001 04 RCPGUEST 0001 06 RCPHCH 0001 20 RCPHOST 0001 60 RCPHREF 0001 40 RCPLOCK 0001 80
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