MEM(4) Device Drivers Manual (luna68k) MEM(4)

mem, kmem
memory files

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 manner as /dev/mem. Only kernel virtual addresses that are currently mapped to memory are allowed.

On the luna68k, physical memory is always contiguous and begins at 0x00000000, and kernel virtual memory also begins at 0x00000000.

/dev/mem
 
/dev/kmem
 

The files mem and kmem appeared in Version 6 AT&T UNIX.
June 12, 2022 NetBSD 10.0