Specifications

Operating System Routines
EXE$QIORETURN
EXE$QIORETURN
Sets a success status code in R0, lowers IPL to 0, and returns to the system
service dispatcher.
Module
SYSQIOREQ
Input
Location Contents
R5 Address of UCB
UCB$B_FLCK Fork lock index or fork IPL
Output
Location Contents
R0 SS$_NORMAL
Synchronization
EXE$QIORETURN is typically called by a driver FDT routine at IPL$_ASTDEL.
Its caller cannot be executing above fork IPL or hold any spinlocks other than the
appropriate fork lock.
EXE$QIORETURN releases any fork lock held by its caller before it issues the
RET instruction.
Description
EXE$QIORETURN performs the following actions:
• Loads SS$_NORMAL into R0
• Lowers IPL to zero
• Issues the RET instruction that restores the original access mode of the
caller of the $QIO system service and returns control to the system service
dispatcher
The image that requested the I/O operation receives status SS$_NORMAL in R0,
indicating that the I/O request has completed without device-independent error.
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