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/.

Linux                                              1992-11-21                                             MEM(4)