MEM(4) 386BSD Programmer's Manual MEM(4)
NAME
mem, kmem - memory files
DESCRIPTION
The special 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. 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.
I386 ARCHETECTURE DETAILS
On ISA the I/O memory space begins at physical address 0x000a0000 and
runs to 0x00100000. The kernel virtual address space (usually) starts at
address 0xfe000000, and each process/thread kernel stack is uniquely
located in the kernel heap above the kernel program.
FILES
/dev/mem
/dev/kmem
HISTORY
The mem, kmem files appeared in Version 6 AT&T UNIX.
BSD Experimental June 2, 1994 1