.\"	$NetBSD: splraiseipl.9,v 1.9 2018/02/08 09:03:23 dholland Exp $
.\"
.\" Copyright (c)2006 YAMAMOTO Takashi,
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.\" ------------------------------------------------------------
.Dd July 9, 2015
.Dt SPLRAISEIPL 9
.Os
.\" ------------------------------------------------------------
.Sh NAME
.Nm splraiseipl
.Nd raise the system priority level
.\" ------------------------------------------------------------
.Sh SYNOPSIS
.In sys/intr.h
.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
.Ft int
.Fn splraiseipl \
"ipl_cookie_t icookie"
.\" ------------------------------------------------------------
.Sh DESCRIPTION
.Fn splraiseipl
raises the system priority level to the level specified by
.Fa icookie .
.Fa icookie
should be a value returned by
.Fn makeiplcookie .
.Pp
In general, device drivers should not make use of this interface.
To ensure correct synchronization, device drivers should use the
.Xr condvar 9 ,
.Xr mutex 9 ,
and
.Xr rwlock 9
interfaces.
.Pp
See the
.Xr spl 9
manual page for a description of interrupt priority levels.
.\" ------------------------------------------------------------
.Sh RETURN VALUES
.Fn splraiseipl
returns saved priority level which can be used for
.Fn splx .
.\" ------------------------------------------------------------
.Sh EXAMPLES
The following two lines are functional equivalents.
.Bd -literal
	s = splraiseipl(makeiplcookie(IPL_VM));
.Ed
.Bd -literal
	s = splvm();
.Ed
.Pp
Because
.Fn makeiplcookie
can be slow and is not expected to be used in a performance critical path,
it's better to do it beforehand.
.Bd -literal
	initialization_code(ipl_t ipl)
	{

		ourcookie = makeiplcookie(ipl);
	}

	performance_critical_code()
	{
		int s;

		s = splraiseipl(ourcookie);
		do_something();
		splx(s);
	}
.Ed
.\" ------------------------------------------------------------
.Sh SEE ALSO
.Xr condvar 9 ,
.Xr makeiplcookie 9 ,
.Xr mutex 9 ,
.Xr rwlock 9 ,
.Xr spl 9