mem

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 mem-
       ory 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
       chown(1), mknod(1), ioperm(2)



Linux				  1992-11-21			       MEM(4)