IFSNT

Prolog  

Control Block Contents  
   IFSNT DSECT

Storage Layout  

Cross Reference (Contains links to field and bit definitions)  

IFSNT Prolog

 NAME       : HCPIFSNT
 DESCRIPTION: INTERPRETATION FACILITY SUBCHANNEL NUMBER TABLE
 DSECT      : IFSNT
 FUNCTION   : TO ALLOW THE MICROCODE TO DETERMINE IF A SIOF
              INSTRUCTION ISSUED, UNDER SIE, BY THE V=R GUEST SHOULD
              BE PASSED THROUGH OR CAUSE INTERCEPTION.
              THE IFSNT IS A 16K TABLE ON A PAGE FRAME BOUNDARY. IT IS
              CONTAINED IN FIXED, CONTIGUOUS REAL STORAGE. IT CONTAINS
              ONE ENTRY (4 BYTES LONG) FOR EACH DEVICE THAT COULD BE
              SUPPORTED UNDER I/O PASS THROUGH. IT IS ONLY APPLICABLE
              FOR A 370 V=R GUEST. DEVICES WITH ADDRESSES 000 THRU
              FFF ARE SUPPORTED UNDER I/O PASS THROUGH.
              THE MICROCODE USES THE DEVICE ADDRESS OPERAND OF THE
              SIOF INSTRUCTION TO INDEX INTO THE IFSNT. IF THE FIRST
              BYTE OF THE ENTRY IS NON-ZERO, THE SIOF INSTRUCTION
              IS ELIGIBLE TO BE PASSED THROUGH. THE FIRST BYTE THEN
              CONTAINS THE LOGICAL PATH MASK (LPM) TO BE PLACED IN THE
              OPERATION REQUEST BLOCK (ORB) CONSTRUCTED BY THE
              MICROCODE. IF THE FIRST BYTE OF THE ENTRY IS ZERO, SIOF
              MUST CAUSE INTERCEPTION.
              THE SECOND BYTE IS RESERVED AND THE THIRD AND FOURTH
              BYTES CONTAIN THE SUBCHANNEL NUMBER.
 LOCATED BY : THE ADDRESS OF THE REAL STORAGE IS CONTAINED IN SYSVRIFS
              WHENEVER CP CAN ALLOCATE SUFFICIENT STORAGE.
              WHEN A 370 V=R GUEST IS OPERATING UNDER I/O PASS THROUGH
              THE ADDRESS OF THE INITIALIZED TABLE IS IN SIESNORG OF
              THE BASE VMDBK.
 CREATED BY : HCPIOAIT, HCPIOAGS
 DELETED BY : HCPIOARC, HCPIOARS

IFSNT Control Block Content

IFSNT DSECT

Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      IFSNT          INTERPRETATION FACILITY
                                        SUBCHANNEL NUMBER TABLE
0000    0 Bitstring    1 IFSNTLPM       IF NON-ZERO, SIOF CAN BE PASSED
                                        THROUGH FOR THIS DEVICE. THIS
                                        BYTE CONTAINS LPM FOR MICROCODE
                                        BUILT ORB. IF ZERO, SIOF MUST
                                        CAUSE INTERCEPTION.
0001    1 Bitstring    1 *              RESERVED FOR FUTURE IBM USE
0002    2 Signed       2 IFSNTSNO       SUBCHANNEL NUMBER FOR THIS DEVICE
          IFSNTSNO       IFSNTLEN       4096*4 LENGTH OF IFSNT
          .... .1..      IFSNTFCT       4 NUMBER OF FRAMES NEEDED FOR THE
                                        IFSNT

IFSNT Storage Layout

          
*** IFSNT - INTERPRETATION FACILITY SUBCHANNEL NUMBER TABLE
*
*     +------+------+-------------+
*   0 |:NTLPM|//////|  IFSNTSNO   | 4
*     +------+------+-------------+
*
*** IFSNT - INTERPRETATION FACILITY SUBCHANNEL NUMBER TABLE

IFSNT Cross Reference

Symbol         Dspl Value
-------------- ---- -----
IFSNTFCT       0002 04
IFSNTLEN       0002 IFSNTSNO
IFSNTLPM       0000
IFSNTSNO       0002