Technical Reference: Kernel and Subsystems, Volume 1

i_enable Kernel Service

Purpose

Enables interrupt priorities.

Syntax

#include <sys/types.h>
#include <sys/errno.h>
#include <sys/intr.h>

void i_enable ( old) int old;

Parameter

old	Specifies the interrupt priority returned by the i_disable service.

Description

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.

Related Information

The i_disable kernel service, unlock_enable kernel service.

Understanding Interrupts, I/O Kernel Services, Understanding Execution Environments in AIX 5L Version 5.2 Kernel Extensions and Device Support Programming Concepts.