1.\" $NetBSD: mem.4,v 1.2 2003/04/17 10:32:40 wiz Exp $ 2.\" 3.\" Copyright (c) 1991 The Regents of the University of California. 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. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by the University of 17.\" California, Berkeley and its contributors. 18.\" 4. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" from: @(#)mem.4 5.3 (Berkeley) 5/2/91 35.\" 36.Dd July 28, 1995 37.Dt MEM 4 acorn32 38.Os 39.Sh NAME 40.Nm mem , 41.Nm kmem 42.Nd memory files 43.Sh DESCRIPTION 44The special file 45.Nm /dev/mem 46is an interface to the physical memory of the computer. 47Byte offsets in this file are interpreted as physical memory addresses. 48Reading and writing this file is equivalent to reading and writing 49memory itself. 50Only offsets within the bounds of 51.Nm /dev/mem 52are allowed. 53.Pp 54Kernel virtual memory is accessed through the interface 55.Nm /dev/kmem 56in the same manner as 57.Nm /dev/mem . 58Only kernel virtual addresses that are currently mapped to memory are allowed. 59.Pp 60On 61.Tn Acorn RiscPC, A7000(+) and RC7500 systems 62the 63.Tn I/O 64memory space (podule space and SuperIO) begins at physical address 0x03000000 65and runs to 0x033fffff. 66On the RiscPC, EASI space runs from 0x08000000 to 0x0fffffff. 67The 68per-process data 69size 70for the current process 71is 72.Dv UPAGES 73long, and starts at VM_MAXUSER_ADDRESS. 74.Sh FILES 75.Bl -tag -width Pa -compact 76.It Pa /dev/mem 77.It Pa /dev/kmem 78.El 79.Sh HISTORY 80The 81.Nm mem , 82.Nm kmem 83files appeared in 84.At v6 . 85