usr/src/share/man/man4/man4.tahoe/mem.4

.\" Copyright (c) 1986 Regents of the University of California.
.\" All rights reserved.  The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\"
.\"     @(#)mem.4       6.1 (Berkeley) %G%
.\"
.TH MEM 4 ""
.UC 7
.SH NAME
mem, kmem \- main memory
.SH DESCRIPTION
.lg
.I Mem
is a special file that is an image of the main memory
of the computer.
It may be used, for example, to examine
(and even to patch) the system.
.PP
Byte addresses in
.I mem
are interpreted as physical memory addresses.
References to non-existent locations cause errors to be returned.
.PP
Examining and patching device registers is likely
to lead to unexpected results when read-only or write-only
bits are present.
.PP
The file
.I kmem
is the same as
.I mem
except that kernel virtual memory
rather than physical memory is accessed.
.PP
On TAHOE, the I/O page
begins at physical address 0xfff00000 of
.I kmem
and per-process data for the current process
begins at virtual 0xbffff000.
.SH FILES
/dev/mem,
/dev/kmem
.SH BUGS
Memory files are accessed one byte
at a time, an inappropiate method for some
device registers.