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Add short section about devices and device nodes.

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Reviewed by:	murray
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Chern Lee 2001-09-20 21:48:49 +00:00
parent 4b4ed42af7
commit a4aab17018
Notes: svn2git 2020-12-08 03:00:23 +00:00 
svn path=/head/; revision=10774
1 changed files with 54 additions and 1 deletions

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en_US.ISO8859-1/books/handbook/basics/chapter.sgml
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<!--
The FreeBSD Documentation Project
$FreeBSD: doc/en_US.ISO8859-1/books/handbook/basics/chapter.sgml,v 1.45 2001/09/08 00:12:38 murray Exp $
$FreeBSD: doc/en_US.ISO8859-1/books/handbook/basics/chapter.sgml,v 1.46 2001/09/13 00:05:59 chern Exp $
-->
<chapter id="basics">
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will save you much more time in the long run.</para>
</sect1>
<sect1>
<title>Devices and Device Nodes</title>
<para>A device is a term used mostly for hardware-related
activities in a system, including disks, printers, graphics
cards, and keyboards. When FreeBSD boots, the majority
of what FreeBSD displays are devices being detected.
You can look through the boot messages again by viewing
<filename>/var/run/dmesg.boot</filename>.</para>
<para>For example, <devicename>acd0</devicename> is the
first IDE CDROM drive, while <devicename>kbd0</devicename>
represents the keyboard.</para>
<para>Most of these devices in a Unix operating system must be
accessed through a special file called device nodes, which are
located in the <filename>/dev</filename> directory.</para>
<sect2>
<title>Creating Device Nodes</title>
<para>When adding a new device to your system, or compiling
in support for additional devices, a device driver
often-times needs to be created.</para>
<sect3>
<title>MAKEDEV Script</title>
<para>On systems without DEVFS, device nodes are created
using the &man.MAKEDEV.8; script as shown below:</para>
<screen>&prompt.root; cd /dev
&prompt.root; sh MAKEDEV ad1
</screen>
<para>This example would make the proper device nodes
for the second IDE drive when installed.</para>
</sect3>
<sect3>
<title>devfs (Device File System)</title>
<para> The device file system, or devfs, provides access to
kernel's device namespace in the global filesystem namespace.
Instead of having to create and modify device nodes,
devfs maintains this particular filesystem for you.</para>
<para>See the &man.devfs.5; man page for more
information.</para>
<para>devfs is used by default in FreeBSD 5.0.</para>
</sect3>
</sect2>
</sect1>
<sect1>
<title>For More Information...</title>