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83 lines
2.8 KiB
Groff
83 lines
2.8 KiB
Groff
.\" Copyright (c) 1991 The Regents of the University of California.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)mem.4 5.3 (Berkeley) 5/2/91
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.\"
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.Dd May 2, 1991
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.Dt MEM 4 i386
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.Os
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.Sh NAME
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.Nm mem ,
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.Nm kmem
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.Nd memory files
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.Sh DESCRIPTION
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The special file
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.Nm /dev/mem
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is an interface to the physical memory of the computer.
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Byte offsets in this file are interpreted as physical memory addresses.
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Reading and writing this file is equivalent to reading and writing
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memory itself.
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Only offsets within the bounds of
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.Nm /dev/mem
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are allowed.
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.Pp
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Kernel virtual memory is accessed through the interface
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.Nm /dev/kmem
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in the same manner as
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.Nm /dev/mem .
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Only kernel virtual addresses that are currently mapped to memory are allowed.
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.Pp
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On
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.Tn ISA
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the
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.Tn I/O
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memory space begins at physical address 0x000a0000
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and runs to 0x00100000.
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The
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per-process data
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size
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for the current process
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is
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.Dv UPAGES
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long, and ends at virtual
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address 0xf0000000.
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.Sh FILES
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.Bl -tag -width Pa -compact
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.It Pa /dev/mem
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.It Pa /dev/kmem
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.El
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.Sh HISTORY
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The
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.Nm mem ,
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.Nm kmem
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files appeared in
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.At v6 .
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