mem is a character device file
that is an image of the main memory of the
computer. It may be used, for example, to examine (and even patch) the
system.
Byte addresses in
mem are interpreted as physical memory addresses.
References to non-existent locations cause errors to be returned.
Examining and patching is likely to lead to unexpected results
when read-only or write-only bits are present.
It is typically created by:
mknod -m 660 /dev/mem c 1 1
chown root:kmem /dev/mem
The file
kmem is the same as
mem, except that the kernel virtual memory
rather than physical memory is accessed.
It is typically created by:
mknod -m 640 /dev/kmem c 1 2
chown root:kmem /dev/kmem
port is similar to
mem, but the I/O ports are accessed.
It is typically created by:
mknod -m 660 /dev/port c 1 4
chown root:mem /dev/port
