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
       nonexistent 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:kmem /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:kmem /dev/kmem

       port is similar to mem, but the I/O 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

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

COLOPHON

       This  page  is  part of release 3.54 of the Linux man-pages project.  A description of the
       project,    and    information    about    reporting    bugs,    can    be    found     at
       http://www.kernel.org/doc/man-pages/.