Specifications

System Macros Invoked by Drivers

UNLOCK_SYSTEM_PAGES

Terminates a request to lock down a series of system pages.

Format

UNLOCK_SYSTEM_PAGES [ipl]

Parameters

[ipl]

IPL at which to continue execution.

Description

The UNLOCK_SYSTEM_PAGES macro terminates a request to lock down a

series of contiguous system pages. In a code segment that uses this locking

technique, there must be exactly one UNLOCK_SYSTEM_PAGES macro call per

LOCK_SYSTEM_PAGES macro call. When the locked code segment completes,

it must invoke the UNLOCK_SYSTEM_PAGES macro to release all previously

locked pages.

The UNLOCK_SYSTEM_PAGES macro executes under the following conditions:

• When it invokes the UNLOCK_SYSTEM_PAGES macro, the code must

ensure that the stack is exactly as it was when the LOCK_SYSTEM_PAGES

macro was invoked. That is, if the code has pushed anything on the stack, it

must remove it before invoking UNLOCK_SYSTEM_PAGES.

• If it speciﬁed the ipl argument to the LOCK_SYSTEM_PAGES macro, the

code segment must restore the previous IPL, either explicity, through the use

of the ipl argument to the UNLOCK_SYSTEM_PAGES macro, or through the

use of one of the system synchronization macros (UNLOCK, FORKUNLOCK

or DEVICEUNLOCK). If it lowers IPL, the locked code segment must invoke

the appropriate system synchronization macro to release any spinlocks that

were required to protect the resources accessed at the elevated IPL.

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