.\"	$OpenBSD: i386_iopl.2,v 1.5 1996/10/08 01:20:06 michaels Exp $
.\"	$NetBSD: i386_iopl.2,v 1.3 1996/02/27 22:57:25 jtc Exp $
.\"
.\" Copyright (c) 1996 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by John T. Kohl and Charles M. Hannum.
.\"
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.\" modification, are permitted provided that the following conditions
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.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"        This product includes software developed by the NetBSD
.\"        Foundation, Inc. and its contributors.
.\" 4. Neither the name of The NetBSD Foundation nor the names of its
.\"    contributors may be used to endorse or promote products derived
.\"    from this software without specific prior written permission.
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.Dd October 14, 1995
.Dt I386_IOPL 2
.Os
.Sh NAME
.Nm i386_iopl
.Nd change the i386 I/O privilege level
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <machine/sysarch.h>
.Ft int
.Fn i386_iopl "int iopl"
.Sh DESCRIPTION
.Fn i386_iopl
sets the i386 I/O privilege level to the value specified by
.Ar iopl .
This call is restricted to the super-user.
.Sh RETURN VALUES
Upon successful completion,
.Fn i386_iopl
returns 0.
Otherwise, a value of -1 is returned and the global
variable
.Va errno
is set to indicate the error.
.Sh ERRORS
.Fn i386_iopl
will fail if:
.Bl -tag -width [EINVAL]
.It Bq Er EPERM
The caller was not the super-user.
.El
.Sh SEE ALSO
.Xr i386_set_ioperm 2 ,
.Xr i386_get_ioperm 2 .
.Sh REFERENCES
i386 Microprocessor Programmer's Reference Manual, Intel
.Sh WARNING
You can really hose your machine if you enable user-level I/O and
write to hardware ports without care.