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mem(4) - kmem, mem, port, kmem, mem, port - system memory, kernel memory and system ports - man 4 mem

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



NAME
       mem, kmem, port - system memory, kernel memory and system ports

DESCRIPTION
       Mem  is  a character device file(1,n) that is an image of the main memory of
       the computer.  It may be used, for example, to examine (and even patch)
       the system.

       Byte  addresses  in(1,8)  mem  are interpreted as physical memory addresses.
       References to non-existent locations cause errors to be returned.

       Examining and patching is likely to lead  to  unexpected  results  when
       read-only or write-only bits are present.

       It is typically created by:

              mknod(1,2) -m 660 /dev/mem c 1 1
              chown(1,2) root:mem /dev/mem


       The file(1,n) kmem is the same as mem, except that the kernel virtual(5,8) memory
       rather than physical memory is accessed.

       It is typically created by:

              mknod(1,2) -m 640 /dev/kmem c 1 2
              chown(1,2) root:mem /dev/kmem


       Port is similar to mem, but the IO ports are accessed.

       It is typically created by:

              mknod(1,2) -m 660 /dev/port c 1 4
              chown(1,2) root:mem /dev/port


FILES
       /dev/mem
       /dev/kmem
       /dev/port

SEE ALSO
       chown(1,2)(1), mknod(1,2)(1), ioperm(2)



Linux                             1992-11-21                            MEM(4)

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