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).
/dev/mem
/dev/kmem
/dev/kUmem
AT&T UNIX
.
The file
kUmem
appeared in
3.0BSD.