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 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 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 -m 660 /dev/mem c 1 1
              chown root:mem /dev/mem

       The  file  kmem is the same as mem, except that the kernel
       virtual memory rather than physical memory is accessed.

       It is typically created by:

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

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

       It is typically created by:

              mknod -m 660 /dev/port c 1 4
              chown root:mem /dev/port

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

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

Linux                    21 November 1992                       1