1.\" $NetBSD: x86_64_iopl.2,v 1.5 2008/04/30 13:10:50 martin Exp $ 2.\" 3.\" Copyright (c) 1996 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by John T. Kohl and Charles M. Hannum. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 19.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 20.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 21.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 22.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28.\" POSSIBILITY OF SUCH DAMAGE. 29.\" 30.Dd July 3, 2002 31.Dt X86_64_IOPL 2 x86_64 32.Os 33.Sh NAME 34.Nm x86_64_iopl 35.Nd change the x86_64 I/O privilege level 36.Sh LIBRARY 37.Lb libx86_64 38.Sh SYNOPSIS 39.In sys/types.h 40.In machine/sysarch.h 41.Ft int 42.Fn x86_64_iopl "int iopl" 43.Sh DESCRIPTION 44.Fn x86_64_iopl 45sets the x86_64 I/O privilege level to the value specified by 46.Ar iopl . 47This call is restricted to the super-user. 48.Sh RETURN VALUES 49Upon successful completion, 50.Fn x86_64_iopl 51returns 0. 52Otherwise, a value of \-1 is returned and the global 53variable 54.Va errno 55is set to indicate the error. 56.Sh ERRORS 57.Fn x86_64_iopl 58will fail if: 59.Bl -tag -width [EINVAL] 60.It Bq Er EPERM 61The caller was not the super-user, or the operation was not permitted at the 62current security level. 63.El 64.Sh WARNING 65You can really hose your machine if you enable user-level I/O and 66write to hardware ports without care. 67