mirror of
https://git.linuxfromscratch.org/lfs.git
synced 2025-08-03 01:55:46 +01:00
673b0d84ba
git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@3435 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689
106 lines
4.9 KiB
XML
106 lines
4.9 KiB
XML
<?xml version="1.0" encoding="ISO-8859-1"?>
|
|
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN" "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [
|
|
<!ENTITY % general-entities SYSTEM "../general.ent">
|
|
%general-entities;
|
|
]>
|
|
<sect1 id="ch-system-MAKEDEV" xreflabel="Make_devices">
|
|
<title>Creating devices with Make_devices-&makedev-version;</title>
|
|
<?dbhtml filename="makedevices.html"?>
|
|
|
|
<indexterm zone="ch-system-MAKEDEV"><primary sortas="a-Make_devices">Make_devices</primary></indexterm>
|
|
|
|
<para>The Make_devices package contains a script for creating device
|
|
nodes.</para>
|
|
|
|
<screen>&buildtime; 1 SBU
|
|
&diskspace; 160 KB</screen>
|
|
|
|
<para>For its installation Make_devices depends on: Bash, Bzip2,
|
|
Coreutils.</para>
|
|
|
|
|
|
|
|
<sect2>
|
|
<title>Making devices</title>
|
|
|
|
<para>Note that unpacking the
|
|
<filename>make_devices-&makedev-version;.bz2</filename> file doesn't
|
|
create a directory for you to <command>cd</command> into, as the file
|
|
contains only a shell script.</para>
|
|
|
|
<para>Install the <filename>make_devices</filename> script:</para>
|
|
|
|
<screen><userinput>bzcat make_devices-&makedev-version;.bz2 > /dev/make_devices
|
|
chmod 754 /dev/make_devices</userinput></screen>
|
|
|
|
<para>Device nodes are special files: things that can generate or receive data.
|
|
They usually correspond to physical pieces of hardware. Device nodes can be
|
|
created by issuing commands of the form: <command>mknod -m mode name type major
|
|
minor</command>. In such a command, <emphasis>mode</emphasis> is the usual
|
|
octal read/write/execute permissions triplet, and <emphasis>name</emphasis> is
|
|
the name of the device file to be created. It may seem surprising, but the
|
|
device name is actually arbitrary, except that most programs rely on devices
|
|
such as <filename>/dev/null</filename> having their usual names. The remaining
|
|
three parameters tell the kernel what device the node
|
|
actually refers to. The <emphasis>type</emphasis> is a letter, either b or c,
|
|
indicating whether the device is accessed in blocks (such as a hard disk) or
|
|
character by character (such as the console). And <emphasis>major</emphasis>
|
|
and <emphasis>minor</emphasis> are numbers, together forming a code that
|
|
identifies the device to the kernel. A list of the currently assigned device
|
|
numbers for Linux can be found in the file <filename>devices.txt</filename> in
|
|
the <filename class="directory">Documentation</filename> subdirectory of the
|
|
kernel sources.</para>
|
|
|
|
<para>Note that the same major/minor combination is usually assigned to both a
|
|
block and a character device. These are, however, completely unrelated devices
|
|
that cannot be interchanged. A device is identified by the type/major/minor
|
|
triple, not just the major/minor pair, so when creating a device node it is
|
|
important to choose the correct <emphasis>type</emphasis> of device.</para>
|
|
|
|
<para>Because looking up the type/major/minor triples and using
|
|
<command>mknod</command> manually is tedious and error-prone, the
|
|
<filename>make_devices</filename> script has been created. It contains a whole
|
|
series of <command>mknod</command> commands, one for each device, complete with
|
|
recommended name, permissions and group assignment. It has been set up so that
|
|
only a minimal set of commonly used devices is enabled and the other lines are
|
|
commented out. You should open <filename>make_devices</filename> in an editor
|
|
and customize it to your needs. This takes some time, but is very simple. When
|
|
you are satisfied, run the script to create the device files:</para>
|
|
|
|
<screen><userinput>cd /dev
|
|
./make_devices</userinput></screen>
|
|
|
|
<para>If you had success with mounting the devpts file system earlier in
|
|
<xref linkend="ch-system-proc"/>, you can continue with the next section. If you were
|
|
unable to mount devpts, you will have to create a few static ptyXX and ttyXX
|
|
device nodes instead. To do this, open <filename>make_devices</filename> in
|
|
your editor, go to the section <quote>Pseudo-TTY masters</quote> and enable a
|
|
few ptyXX devices -- a handful are enough to enable the test suites to run, but
|
|
if you plan to run a kernel without devpts support you will probably need many
|
|
more (every xterm, ssh connection, telnet connection, and the like, uses one of
|
|
these pseudo terminals). In the immediately following section <quote>Pseudo-TTY
|
|
slaves</quote>, enable the corresponding ttyXX devices. When you are done, rerun
|
|
<command>./make_devices</command> from inside <filename>/dev</filename> to
|
|
have it create the new devices.</para>
|
|
|
|
</sect2>
|
|
|
|
|
|
<sect2 id="contents-makedev"><title>Contents of Make_devices</title>
|
|
|
|
<para><emphasis>Installed script</emphasis>: make_devices</para>
|
|
|
|
</sect2>
|
|
|
|
<sect2><title>Short description</title>
|
|
|
|
<indexterm zone="ch-system-MAKEDEV make_devices"><primary sortas="d-make_devices">make_devices</primary></indexterm>
|
|
<para id="make_devices"><command>make_devices</command> is a script for creating a basic set of
|
|
static device nodes, usually residing in the <filename class="directory">/dev</filename> directory.</para>
|
|
|
|
</sect2>
|
|
|
|
|
|
|
|
</sect1>
|