mirror of https://github.com/mkerrisk/man-pages
85 lines
2.3 KiB
Groff
85 lines
2.3 KiB
Groff
.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
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.\" Fri Apr 2 11:32:09 MET DST 1993
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.\"
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.\" This is free documentation; you can redistribute it and/or
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.\" modify it under the terms of the GNU General Public License as
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.\" published by the Free Software Foundation; either version 2 of
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.\" the License, or (at your option) any later version.
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.\"
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.\" The GNU General Public License's references to "object code"
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.\" and "executables" are to be interpreted as the output of any
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.\" document formatting or typesetting system, including
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.\" intermediate and printed output.
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.\"
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.\" This manual is distributed in the hope that it will be useful,
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.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
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.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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.\" GNU General Public License for more details.
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.\"
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.\" You should have received a copy of the GNU General Public
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.\" License along with this manual; if not, write to the Free
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.\" Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111,
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.\" USA.
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.\"
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.\" Modified Sat Jul 24 16:59:10 1993 by Rik Faith (faith@cs.unc.edu)
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.TH MEM 4 1992-11-21 "Linux" "Linux Programmer's Manual"
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.SH NAME
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mem, kmem, port \- system memory, kernel memory and system ports
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.SH DESCRIPTION
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\fBmem\fP is a character device file
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that is an image of the main memory of the computer.
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It may be used, for example, to examine (and even patch) the system.
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.LP
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Byte addresses in
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.B mem
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are interpreted as physical memory addresses.
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References to nonexistent locations cause errors to be returned.
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.LP
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Examining and patching is likely to lead to unexpected results
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when read-only or write-only bits are present.
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.LP
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It is typically created by:
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.RS
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.sp
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mknod \-m 660 /dev/mem c 1 1
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.br
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chown root:kmem /dev/mem
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.RE
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.LP
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The file
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.B kmem
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is the same as
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.BR mem ,
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except that the kernel virtual memory
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rather than physical memory is accessed.
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.LP
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It is typically created by:
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.RS
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.sp
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mknod \-m 640 /dev/kmem c 1 2
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.br
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chown root:kmem /dev/kmem
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.RE
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.LP
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\fBport\fP is similar to
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.BR mem ,
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but the I/O ports are accessed.
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.LP
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It is typically created by:
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.RS
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.sp
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mknod \-m 660 /dev/port c 1 4
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.br
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chown root:mem /dev/port
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.RE
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.SH FILES
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.I /dev/mem
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.br
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.I /dev/kmem
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.br
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.I /dev/port
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.SH "SEE ALSO"
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.BR chown (1),
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.BR mknod (1),
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.BR ioperm (2)
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