1MEM(4)                     Linux Programmer's Manual                    MEM(4)
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NAME

6       mem, kmem, port - system memory, kernel memory and system ports
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DESCRIPTION

9       mem  is  a character device file that is an image of the main memory of
10       the computer.  It may be used, for example, to examine (and even patch)
11       the system.
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13       Byte  addresses  in  mem  are interpreted as physical memory addresses.
14       References to non-existent locations cause errors to be returned.
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16       Examining and patching is likely to lead  to  unexpected  results  when
17       read-only or write-only bits are present.
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19       It is typically created by:
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21              mknod -m 660 /dev/mem c 1 1
22              chown root:kmem /dev/mem
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25       The file kmem is the same as mem, except that the kernel virtual memory
26       rather than physical memory is accessed.
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28       It is typically created by:
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30              mknod -m 640 /dev/kmem c 1 2
31              chown root:kmem /dev/kmem
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34       port is similar to mem, but the I/O ports are accessed.
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36       It is typically created by:
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38              mknod -m 660 /dev/port c 1 4
39              chown root:mem /dev/port
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FILES

43       /dev/mem
44       /dev/kmem
45       /dev/port
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SEE ALSO

48       chown(1), mknod(1), ioperm(2)
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52Linux                             1992-11-21                            MEM(4)