86 lines
2.8 KiB
Groff
86 lines
2.8 KiB
Groff
.\" $NetBSD: splraise.9,v 1.1 2010/02/06 22:32:08 dyoung Exp $
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.\"
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.\" Copyright (c) 2010 David Young. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. The name of the author may not be used to endorse or promote products
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.\" derived from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd February 5, 2010
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.Dt SPLRAISE 9
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.Os
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.Sh NAME
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.Nm spllower ,
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.Nm splraise
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.Nd modify system interrupt priority level
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.Sh SYNOPSIS
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.In machine/intr.h
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.Ft void
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.Fn spllower "int s"
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.Ft int
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.Fn splraise "int s"
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.Sh DESCRIPTION
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These functions raise and lower the interrupt priority level
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on i386.
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They are used by machine-dependent kernel code to implement
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the machine-independent
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.Xr spl 9
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interface.
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.Pp
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In a multi-CPU system, these functions change the interrupt
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priority level on the local CPU only.
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In general, device drivers should not make use of these functions.
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.Pp
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The
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.Fn spllower
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function sets the system priority level to the one encoded in
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.Fa s ,
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if
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.Fa s
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is lower than the current level.
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Otherwise, it does not change the level.
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Use
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.Fn splx
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instead
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of
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.Fn spllower ,
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except in extraordinary circumstances.
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.Pp
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The
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.Fn splraise
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function sets the system priority level to the one encoded in
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.Fa s ,
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if
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.Fa s
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is greater than the current level, and returns the previous level.
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Otherwise, it does not change the level, and it returns the current level.
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Except in extraordinary circumstances,
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do not use
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.Fn splraise .
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Use one of the priority-raising functions defined in
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.Xr spl 9 ,
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instead.
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.Sh SEE ALSO
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.Xr condvar 9 ,
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.Xr mutex 9 ,
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.Xr rwlock 9 ,
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.Xr spl 9
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