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Devicesmem(7D)


NAME

 mem, kmem - physical or virtual memory

SYNOPSIS

 
/dev/mem 
 
/dev/kmem 

DESCRIPTION

 

The file /dev/mem is a special file that is an image of the physical memory of the computer. The file /dev/kmem is a special file that is an image of the kernel virtual memory of the computer. Either may be used, for example, to examine, and even patch the system.

Byte addresses in /dev/mem are interpreted as physical memory addresses. Byte addresses in /dev/kmem are interpreted as kernel virtual memory addresses. References to non-existent locations cause errors to be returned.

The file /dev/kmem accesses up to 4GB of kernel virtual memory. The file /dev/mem accesses physical memory; the size of the file is equal to the amount of physical memory in the computer. This can be larger than 4GB; in which case, memory beyond 4GB can be accessed using a series of read(2) and write(2) commands or a combination of llseek(2) and read(2) and write(2).

ERRORS

 
EFAULT
Bad address. This error can occur when trying to: write(2) a read-only location, read(2) a write-only location, or read(2) or write(2) a non-existent or unimplemented location.
ENXIO
This error results from attempting to mmap(2) a non-existent physical (mem) or virtual (kmem) memory address.

FILES

 
/dev/mem
File containing image of physical memory of computer.
/dev/kmem
File containing image of kernel virtual memory of computer.

SEE ALSO

 

llseek(2), mmap(2), read(2), write(2)

NOTES

 

Some of /dev/kmem cannot be read because of write-only addresses or unequipped memory addresses.


SunOS 5.9Go To TopLast Changed 18 Mar 1994

 
      
      
Copyright 2002 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms.