.\"	$NetBSD: splraise.9,v 1.1 2010/02/06 22:32:08 dyoung Exp $
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.Dd February 5, 2010
.Dt SPLRAISE 9
.Os
.Sh NAME
.Nm spllower ,
.Nm splraise
.Nd modify system interrupt priority level
.Sh SYNOPSIS
.In machine/intr.h
.Ft void
.Fn spllower "int s"
.Ft int
.Fn splraise "int s"
.Sh DESCRIPTION
These functions raise and lower the interrupt priority level
on i386.
They are used by machine-dependent kernel code to implement
the machine-independent
.Xr spl 9
interface.
.Pp
In a multi-CPU system, these functions change the interrupt
priority level on the local CPU only.
In general, device drivers should not make use of these functions.
.Pp
The
.Fn spllower
function sets the system priority level to the one encoded in
.Fa s ,
if
.Fa s
is lower than the current level.
Otherwise, it does not change the level.
Use
.Fn splx
instead
of
.Fn spllower ,
except in extraordinary circumstances.
.Pp
The
.Fn splraise
function sets the system priority level to the one encoded in
.Fa s ,
if
.Fa s
is greater than the current level, and returns the previous level.
Otherwise, it does not change the level, and it returns the current level.
Except in extraordinary circumstances,
do not use
.Fn splraise .
Use one of the priority-raising functions defined in
.Xr spl 9 ,
instead.
.Sh SEE ALSO
.Xr condvar 9 ,
.Xr mutex 9 ,
.Xr rwlock 9 ,
.Xr spl 9