MEM(4) | Device Drivers Manual (hp300) | MEM(4) |
mem
, kmem
—
main memory
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 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
.
The files mem
and
kmem
appeared in Version 6
AT&T UNIX.
June 5, 1993 | NetBSD 10.99 |