1.\" $NetBSD: splraise.9,v 1.1 2010/02/06 22:32:08 dyoung Exp $ 2.\" 3.\" Copyright (c) 2010 David Young. All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 3. The name of the author may not be used to endorse or promote products 14.\" derived from this software without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26.\" 27.Dd February 5, 2010 28.Dt SPLRAISE 9 29.Os 30.Sh NAME 31.Nm spllower , 32.Nm splraise 33.Nd modify system interrupt priority level 34.Sh SYNOPSIS 35.In machine/intr.h 36.Ft void 37.Fn spllower "int s" 38.Ft int 39.Fn splraise "int s" 40.Sh DESCRIPTION 41These functions raise and lower the interrupt priority level 42on i386. 43They are used by machine-dependent kernel code to implement 44the machine-independent 45.Xr spl 9 46interface. 47.Pp 48In a multi-CPU system, these functions change the interrupt 49priority level on the local CPU only. 50In general, device drivers should not make use of these functions. 51.Pp 52The 53.Fn spllower 54function sets the system priority level to the one encoded in 55.Fa s , 56if 57.Fa s 58is lower than the current level. 59Otherwise, it does not change the level. 60Use 61.Fn splx 62instead 63of 64.Fn spllower , 65except in extraordinary circumstances. 66.Pp 67The 68.Fn splraise 69function sets the system priority level to the one encoded in 70.Fa s , 71if 72.Fa s 73is greater than the current level, and returns the previous level. 74Otherwise, it does not change the level, and it returns the current level. 75Except in extraordinary circumstances, 76do not use 77.Fn splraise . 78Use one of the priority-raising functions defined in 79.Xr spl 9 , 80instead. 81.Sh SEE ALSO 82.Xr condvar 9 , 83.Xr mutex 9 , 84.Xr rwlock 9 , 85.Xr spl 9 86