Programming Interface Information:
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EASIT
Control Block Contents
EASIT DSECT
Cross Reference (Contains links to field and bit definitions)
EASIT Prolog
Name : HCPEASIT Description: External-Address-Space-Identification Token DSECT : EASIT Function : This DSECT maps an e-ASIT, which is CP's external identification of an address space, and a guest's identification of a host address space. Located by : Any task accepting an e-ASIT from a guest, or providing one to a guest. Created by : HCPSITIE when translating an i-ASIT into an e-ASIT. Deleted by : Any task which no longer needs the representation. Notes : An e-ASIT is an eight-byte token, doubleword aligned, and serves as an external representation of an address space. In external documentation, "ASIT" is used to designate an e-ASIT. An e-ASIT is given to guests to represent an address space, and is guaranteed to be a system-wide unique token, and unique for the life of the current system IPL. When referring to the same address space, the same token is given to different guests. A test for equality can therefore be used to see if two e-ASITs represent the same address space. Since an e-ASIT can also be received from guests, it must also be "verifiable". That is, CP must be able to reliably decide when a supposed e-ASIT is a legal token designating an existing address space.
EASIT Control Block Content
EASIT DSECT
Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure EASIT External-Address-Space-Identifica tion space-identification token. 0000 0 Address 4 EASASTEO Bits 1-25 are the ASTE origin ..11 1111 EASASTOB X'8000003F' Mask used to check for invalid bits in EASASTEO field. Bits 0 and 26-32 are unused and will be zeros when generated by CP, and must be zeros when generated by a guest. 0004 4 Signed 4 EASSCRSN E-ASIT space creation sequence number. 00000008 EASLEN *-EASIT Length in bytes of an e-ASIT 00000001 EASSIZE (EASLEN+7)/8 Size in doublewords of an e-ASIT
EASIT Storage Layout
*** EASIT - External-Address-Space-Identification * * +---------------------------+---------------------------+ * 0 | EASASTEO | EASSCRSN | * +---------------------------+---------------------------+ * 8 * *** EASIT - External-Address-Space-Identification
EASIT Cross Reference
Symbol Dspl Value -------------- ---- ----- EASASTEO 0000 EASASTOB 0000 3F EASLEN 0004 00000008 EASSCRSN 0004 EASSIZE 0004 00000001
Last updated on 5 Jun 2001 at 13:31:12 EDT.
Copyright IBM Corporation, 1990, 2001