1.\" $OpenBSD: xf86.4,v 1.4 2002/08/24 17:21:44 matthieu Exp $ 2.\" 3.\" Copyright (c) 1998 Matthieu Herrb 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. The name of the author may not be used to endorse or promote products 15.\" derived from this software without specific prior written permission 16.\" 17.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27.\" 28.Dd February 20, 1998 29.Dt XF86 4 30.Os 31.Sh NAME 32.Nm xf86 33.Nd XFree86 aperture driver 34.Sh SYNOPSIS 35.Cd "option APERTURE" 36.Sh DESCRIPTION 37On 38.Va alpha Ns , 39.Va i386 Ns , 40.Va macppc 41and 42.Va sparc64 43the 44.Pa /dev/xf86 45driver provides access to the memory and I/O ports of a VGA board 46and to the PCI configuration registers 47for use by the XFree86 X servers 48when running with a kernel security level > 0. 49.Pp 50The X servers require the use of this driver. 51.Sh ACCESS CONTROL 52Access to the 53.Pa /dev/xf86 54device is allowed when the sysctl variable 55.Va machdep.allowaperture 56>= 1. 57This variable (which default value is 0) 58can only be manipulated when the security level is <= 0, so it should be 59set in 60.Pa /etc/sysctl.conf . 61The possible values for 62.Va machdep.allowaperture 63are: 64.Bl -tag -width Ds 65.It 0 66the aperture driver is disabled. 67Opening it returns 68.Dv EPERM. 69.It 1 70the aperture driver allows access to standard VGA framebuffer and BIOS. 71Access to 72.Xr pci 4 73configuration registers is also allowed. 74.It 2 75in addition to allowing access to 76.Xr pci 4 77configuration registers, 78the aperture driver allows access to the whole 1st megabyte of physical 79memory, permitting use of the int10 emulation in XFree86 4.0.x. 80Note that this can cause some security problems, since the process that 81has access to the aperture driver can also access part of the kernel 82memory. 83This mode is not supported on alpha or sparc64. 84.El 85.Sh SEE ALSO 86.Xr XF86_Accel 1 , 87.Xr XF86_SVGA 1 , 88.Xr options 4 , 89.Xr pci 4 , 90.Xr sysctl.conf 5 , 91.Xr config 8 , 92.Xr sysctl 8 93.Sh HISTORY 94.Pa /dev/xf86 95was introduced as a loadable kernel module for 96.Nx 0.9 c 97with XFree86 3.1. 98It was integrated as an in-kernel device on 99.Ox 2.3 . 100It is required in order to allow access to I/O ports for all X servers since 101.Ox 2.4 . 102.Sh AUTHORS 103The aperture driver was written by Matthieu Herrb. 104.Sh BUGS 105This driver allows access to all addresses above 106.Va physmem . 107It should be restricted to the actual address range of the video 108memory. 109