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AIX Version 4.3 Kernel and Subsystems Technical Reference, Volume 1

i_enable Kernel Service


Enables interrupt priorities.


#include <sys/types.h>
#include <sys/errno.h>
#include <sys/intr.h>
void i_enable (old)
int old;


old Specifies the interrupt priority returned by the i_disable service.


The i_enable service restores the interrupt priority to a less-favored value. This value should be the value that was in effect before the corresponding call to the i_disable service.

Note: When serializing a thread with an interrupt handler in a multiprocessor-safe kernel extension, locking must be used as well as interrupt control. For this reason, new code should call the unlock_enable kernel service instead of i_enable. The unlock_enable service performs locking only on multiprocessor systems, and helps ensure that code is portable between uniprocessor and multiprocessor systems.

Execution Environment

The i_enable kernel service can be called from either the process or interrupt environment.

Return Values

The i_enable service has no return values.

Implementation Specifics

The i_enable kernel service is part of Base Operating System (BOS) Runtime.

Related Information

The i_disable kernel service, unlock_enable kernel service.

Understanding Interrupts, I/O Kernel Services, Understanding Execution Environments in AIX Kernel Extensions and Device Support Programming Concepts.

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