Specifications

Operating System Routines
IOC$LOADALTMAP
IOC$LOADALTMAP
Loads a set of Q22–bus alternate map registers.
Module
[SYSLOA]MAPSUBxxx
Macro
LOADALT
Input
Location Contents
R5 Address of UCB
UCB$W_BCNT Number of bytes in transfer
UCB$W_BOFF Byte offset in first page of transfer
UCB$L_SVAPTE System virtual address of PTE for first page of
transfer
UCB$L_CRB Address of CRB
CRB$L_INTD+
VEC$W_NUMALT
Number of alternate map registers allocated
CRB$L_INTD+
VEC$W_MAPALT
Number of first alternate map register allocated
CRB$L_INTD+
VEC$L_ADP
Address of ADP
ADP$L_MR2ADDR Address of the first Q22–bus alternate map register
Output
Location Contents
R0 SS$_NORMAL, SS$_INSFMAPREG, or
SS$_SSFAIL
R1, R2 Destroyed
Synchronization
A driver fork process calls IOC$LOADALTMAP at fork IPL, holding the
corresponding fork lock in a multiprocessing environment. IOC$LOADALTMAP
returns control to its caller at the caller’s IPL. The caller retains any spinlocks it
held at the time of the call.
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