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Diffstat (limited to 'man/man4/mem.4')
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diff --git a/man/man4/mem.4 b/man/man4/mem.4 new file mode 100644 index 000000000..5bc14bbb6 --- /dev/null +++ b/man/man4/mem.4 @@ -0,0 +1,81 @@ +.\" Copyright (c) 1993 Michael Haardt (michael@moria.de), +.\" Fri Apr 2 11:32:09 MET DST 1993 +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.\" Modified Sat Jul 24 16:59:10 1993 by Rik Faith (faith@cs.unc.edu) +.TH mem 4 (date) "Linux man-pages (unreleased)" +.SH NAME +mem, kmem, port \- system memory, kernel memory and system ports +.SH DESCRIPTION +.I /dev/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. +.P +Byte addresses in +.I /dev/mem +are interpreted as physical memory addresses. +References to nonexistent locations cause errors to be returned. +.P +Examining and patching is likely to lead to unexpected results +when read-only or write-only bits are present. +.P +Since Linux 2.6.26, and depending on the architecture, the +.B CONFIG_STRICT_DEVMEM +kernel configuration option limits the areas +which can be accessed through this file. +For example: on x86, RAM access is not allowed but accessing +memory-mapped PCI regions is. +.P +It is typically created by: +.P +.in +4n +.EX +mknod \-m 660 /dev/mem c 1 1 +chown root:kmem /dev/mem +.EE +.in +.P +The file +.I /dev/kmem +is the same as +.IR /dev/mem , +except that the kernel virtual memory +rather than physical memory is accessed. +Since Linux 2.6.26, this file is available only if the +.B CONFIG_DEVKMEM +kernel configuration option is enabled. +.P +It is typically created by: +.P +.in +4n +.EX +mknod \-m 640 /dev/kmem c 1 2 +chown root:kmem /dev/kmem +.EE +.in +.P +.I /dev/port +is similar to +.IR /dev/mem , +but the I/O ports are accessed. +.P +It is typically created by: +.P +.in +4n +.EX +mknod \-m 660 /dev/port c 1 4 +chown root:kmem /dev/port +.EE +.in +.SH FILES +.I /dev/mem +.br +.I /dev/kmem +.br +.I /dev/port +.SH SEE ALSO +.BR chown (1), +.BR mknod (1), +.BR ioperm (2) |