Devices                                                   mem(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 exam-
     ine, and even patch the system.

     Byte addresses  in  /dev/mem  are  interpreted  as  physical
     memory  addresses.  Byte  addresses  in /dev/kmem are inter-
     preted 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 com-
           puter.

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

NOTES

SunOS 5.8           Last change: 18 Mar 1994                    1

Devices                                                   mem(7D)

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

SunOS 5.8           Last change: 18 Mar 1994                    2