mem(4) - NetBSD Manual Pages

MEM(4)               NetBSD/hp300 Kernel Interfaces Manual              MEM(4)


NAME

     mem, kmem -- main memory


DESCRIPTION

     The file /dev/mem is an interface to the physical memory of the computer.
     Byte offsets in this file are interpreted as physical memory addresses.
     Reading and writing this file is equivalent to reading and writing memory
     itself.  An error will be returned if an attempt is made to reference an
     offset outside of /dev/mem.

     Kernel virtual memory is accessed via the file /dev/kmem in the same man-
     ner as /dev/mem.  Only kernel virtual addresses that are currently mapped
     to memory are allowed.

HP300
     On the HP300, the last byte of physical memory is always 0xFFFFFFFF.
     Therefore, on an HP300 with 8MB of memory, physical memory would start at
     0xFF800000.  On the HP300, kernel virtual memory runs from 0 to about
     0x2400000.


FILES

     /dev/mem
     /dev/kmem


HISTORY

     The files mem and kmem appeared in Version 6 AT&T UNIX.

NetBSD 9.0                       June 5, 1993                       NetBSD 9.0