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.\" $OpenBSD: ap.4,v 1.2 1999/05/16 19:56:13 alex Exp $
.\"
.\" Copyright (c) 1991 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\" must display the following acknowledgement:
.\" This product includes software developed by the University of
.\" California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" from: @(#)mem.4 5.3 (Berkeley) 5/2/91
.\" from Id: mem.4,v 1.1.1.1 1995/10/18 08:44:29 deraadt Exp
.\"
.Dd Jan 19, 1997
.Dt AP 4
.Os
.Sh NAME
.Nm xf86
.Nd XFree86 Framebuffer aperture driver
.Sh DESCRIPTION
This module was written to help work around the security feature of
the OS that prevents read/write access to /dev/mem.
.Pp
XFree86 can take advantage of having direct access to video
memory (especially with VLB and PCI cards) and even requires it for
the P9000 server.
.Pp
This driver works like the standard
.Nm /dev/mem
driver. It just allows
mapping of the VGA framebuffer even if kernel security level is > 0.
The driver only implements the
.Xr open 2 ,
.Xr close 2 ,
.Xr mmap 2
calls. In
order not to defeat kernel security, only one open() at a time is
allowed and only a process with effective user id of 0 can perform
it. So while you're running XFree86, no other process will be allowed
to open
.Nm /dev/xf86
.Sh FILES
.Bl -tag -width Pa -compact
.It Pa /dev/xf86
.El
.Sh SEE ALSO
.Xr kmem 4 ,
.Xr mem 4
.Sh HISTORY
This work is heavily inspired from the Solaris x86 aperture driver by
Doug Anson (danson@lgc.com) and David Holland (davidh@use.com).
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