1.\" $NetBSD: x86_64_iopl.2,v 1.3 2002/10/01 16:02:43 wiz 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.\" 3. All advertising materials mentioning features or use of this software 18.\" must display the following acknowledgement: 19.\" This product includes software developed by the NetBSD 20.\" Foundation, Inc. and its contributors. 21.\" 4. Neither the name of The NetBSD Foundation nor the names of its 22.\" contributors may be used to endorse or promote products derived 23.\" from this software without specific prior written permission. 24.\" 25.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 26.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 27.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 28.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 29.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 30.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 31.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 32.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 33.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 34.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 35.\" POSSIBILITY OF SUCH DAMAGE. 36.\" 37.Dd July 3, 2002 38.Dt X86_64_IOPL 2 x86_64 39.Os 40.Sh NAME 41.Nm x86_64_iopl 42.Nd change the x86_64 I/O privilege level 43.Sh LIBRARY 44.Lb libx86_64 45.Sh SYNOPSIS 46.Fd #include \*[Lt]sys/types.h\*[Gt] 47.Fd #include \*[Lt]machine/sysarch.h\*[Gt] 48.Ft int 49.Fn x86_64_iopl "int iopl" 50.Sh DESCRIPTION 51.Fn x86_64_iopl 52sets the x86_64 I/O privilege level to the value specified by 53.Ar iopl . 54This call is restricted to the super-user. 55.Sh RETURN VALUES 56Upon successful completion, 57.Fn x86_64_iopl 58returns 0. 59Otherwise, a value of \-1 is returned and the global 60variable 61.Va errno 62is set to indicate the error. 63.Sh ERRORS 64.Fn x86_64_iopl 65will fail if: 66.Bl -tag -width [EINVAL] 67.It Bq Er EPERM 68The caller was not the super-user, or the operation was not permitted at the 69current security level. 70.El 71.Sh WARNING 72You can really hose your machine if you enable user-level I/O and 73write to hardware ports without care. 74