| MEM(4) | Device Drivers Manual (x86) | MEM(4) | 
mem, kmem —
/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. Only offsets within the bounds of
  /dev/mem are allowed.
Kernel virtual memory is accessed through the interface
    /dev/kmem in the same manner as
    /dev/mem. Only kernel virtual addresses that are
    currently mapped to memory are allowed.
On ISA the I/O memory space begins at physical address 0x000a0000
    and runs to 0x00100000. The per-process data size for the current process is
    UPAGES long, and ends at virtual address
  0xfe000000.
mem, kmem files appeared in
  Version 6 AT&T UNIX.
| September 23, 2011 | NetBSD 10.1 |