Specifications

System Macros Invoked by Drivers

ENBINT

Lowers the local processor’s IPL to a speciﬁed value, thus permitting interrupts

to occur at or beneath the current IPL.

Format

ENBINT [src=(SP)+]

Parameters

[src=(SP)+]

Location containing the IPL to be restored to the processor IPL register (PR$_

IPL) of the local processor. If you do not specify a value in src, ENBINT moves

the value on the top of the stack into PR$_IPL.

Description

The ENBINT macro complements the actions of the DSBINT macro, restoring an

IPL value to PR$_IPL. Procedures invoke this macro to lower IPL to a previously

saved level. If an interrupt is pending at the current IPL or at any IPL above the

IPL speciﬁed by src, the current procedure is immediately interrupted.

Note that the DSBINT and ENBINT macros only provide full synchronization

in a uniprocessor environment. In multiprocessor conﬁgurations, DSBINT

and ENBINT are only suitable for blocking events on the local processor. To

provide synchronized access to system resources and devices in a multiprocessing

environment, you must use the DEVICELOCK/DEVICEUNLOCK, FORKLOCK

/FORKUNLOCK, and LOCK/UNLOCK macros.

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