MEM
Section: Devices and Network Interfaces (4)
Updated: vax
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BSD mandoc
BSD 4
NAME
mem
kmem
kUmem
- 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.
The file
/dev/kUmem
also refers to kernel virtual memory,
but may be used to access areas mapped to
UNIBUS
address space
and other
I/O
areas.
It forces all accesses to use word (short integer) accesses.
On the
VAX
11/780,
the
I/O
space base address is
20000000(16);
on an 11/750
the
I/O space addresses are of the form fxxxxx(16).
On all
VAX 'en
the
per-process data
size
for the current process
is
UPAGES
long and ends at the virtual address 80000000(16).
FILES
- /dev/mem
-
- /dev/kmem
-
- /dev/kUmem
-
HISTORY
The
mem
kmem
files appeared in
AT&T System
v6 .
The file
kUmem
appeared in
BSD 3.0
Index
- NAME
-
- DESCRIPTION
-
- FILES
-
- HISTORY
-
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Time: 06:48:45 GMT, May 19, 2025