[673b0d8] | 1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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| 2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN" "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [
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| 3 | <!ENTITY % general-entities SYSTEM "../general.ent">
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| 4 | %general-entities;
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| 5 | ]>
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[540fd31] | 6 | <sect1 id="ch-system-MAKEDEV" xreflabel="Make_devices">
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| 7 | <title>Creating devices with Make_devices-&makedev-version;</title>
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[673b0d8] | 8 | <?dbhtml filename="makedevices.html"?>
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| 9 |
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| 10 | <indexterm zone="ch-system-MAKEDEV"><primary sortas="a-Make_devices">Make_devices</primary></indexterm>
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[2602f8d] | 11 |
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[540fd31] | 12 | <para>The Make_devices package contains a script for creating device
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| 13 | nodes.</para>
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[5888299] | 14 |
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[673b0d8] | 15 | <screen>&buildtime; 1 SBU
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| 16 | &diskspace; 160 KB</screen>
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| 17 |
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| 18 | <para>For its installation Make_devices depends on: Bash, Bzip2,
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| 19 | Coreutils.</para>
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[0ea89f72] | 20 |
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[73aedd1d] | 21 |
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| 22 |
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| 23 | <sect2>
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[5888299] | 24 | <title>Making devices</title>
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[73aedd1d] | 25 |
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[540fd31] | 26 | <para>Note that unpacking the
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| 27 | <filename>make_devices-&makedev-version;.bz2</filename> file doesn't
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| 28 | create a directory for you to <command>cd</command> into, as the file
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| 29 | contains only a shell script.</para>
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| 30 |
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| 31 | <para>Install the <filename>make_devices</filename> script:</para>
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| 32 |
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| 33 | <screen><userinput>bzcat make_devices-&makedev-version;.bz2 > /dev/make_devices
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| 34 | chmod 754 /dev/make_devices</userinput></screen>
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| 35 |
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| 36 | <para>Device nodes are special files: things that can generate or receive data.
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[5cd6caa] | 37 | They usually correspond to physical pieces of hardware. Device nodes can be
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| 38 | created by issuing commands of the form: <command>mknod -m mode name type major
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[540fd31] | 39 | minor</command>. In such a command, <emphasis>mode</emphasis> is the usual
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| 40 | octal read/write/execute permissions triplet, and <emphasis>name</emphasis> is
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| 41 | the name of the device file to be created. It may seem surprising, but the
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| 42 | device name is actually arbitrary, except that most programs rely on devices
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| 43 | such as <filename>/dev/null</filename> having their usual names. The remaining
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[5cd6caa] | 44 | three parameters tell the kernel what device the node
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[540fd31] | 45 | actually refers to. The <emphasis>type</emphasis> is a letter, either b or c,
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| 46 | indicating whether the device is accessed in blocks (such as a hard disk) or
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| 47 | character by character (such as the console). And <emphasis>major</emphasis>
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| 48 | and <emphasis>minor</emphasis> are numbers, together forming a code that
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| 49 | identifies the device to the kernel. A list of the currently assigned device
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| 50 | numbers for Linux can be found in the file <filename>devices.txt</filename> in
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| 51 | the <filename class="directory">Documentation</filename> subdirectory of the
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| 52 | kernel sources.</para>
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| 53 |
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[5cd6caa] | 54 | <para>Note that the same major/minor combination is usually assigned to both a
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[540fd31] | 55 | block and a character device. These are, however, completely unrelated devices
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| 56 | that cannot be interchanged. A device is identified by the type/major/minor
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| 57 | triple, not just the major/minor pair, so when creating a device node it is
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| 58 | important to choose the correct <emphasis>type</emphasis> of device.</para>
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| 59 |
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| 60 | <para>Because looking up the type/major/minor triples and using
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| 61 | <command>mknod</command> manually is tedious and error-prone, the
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| 62 | <filename>make_devices</filename> script has been created. It contains a whole
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| 63 | series of <command>mknod</command> commands, one for each device, complete with
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| 64 | recommended name, permissions and group assignment. It has been set up so that
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| 65 | only a minimal set of commonly used devices is enabled and the other lines are
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| 66 | commented out. You should open <filename>make_devices</filename> in an editor
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| 67 | and customize it to your needs. This takes some time, but is very simple. When
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| 68 | you are satisfied, run the script to create the device files:</para>
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[73aedd1d] | 69 |
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[540fd31] | 70 | <screen><userinput>cd /dev
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| 71 | ./make_devices</userinput></screen>
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[73aedd1d] | 72 |
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[673b0d8] | 73 | <para>If you had success with mounting the devpts file system earlier in
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| 74 | <xref linkend="ch-system-proc"/>, you can continue with the next section. If you were
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[e1c7e32] | 75 | unable to mount devpts, you will have to create a few static ptyXX and ttyXX
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| 76 | device nodes instead. To do this, open <filename>make_devices</filename> in
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[673b0d8] | 77 | your editor, go to the section <quote>Pseudo-TTY masters</quote> and enable a
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| 78 | few ptyXX devices -- a handful are enough to enable the test suites to run, but
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| 79 | if you plan to run a kernel without devpts support you will probably need many
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| 80 | more (every xterm, ssh connection, telnet connection, and the like, uses one of
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| 81 | these pseudo terminals). In the immediately following section <quote>Pseudo-TTY
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| 82 | slaves</quote>, enable the corresponding ttyXX devices. When you are done, rerun
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[e1c7e32] | 83 | <command>./make_devices</command> from inside <filename>/dev</filename> to
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| 84 | have it create the new devices.</para>
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[73aedd1d] | 85 |
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| 86 | </sect2>
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[2602f8d] | 87 |
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[5888299] | 88 |
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[673b0d8] | 89 | <sect2 id="contents-makedev"><title>Contents of Make_devices</title>
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| 90 |
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| 91 | <para><emphasis>Installed script</emphasis>: make_devices</para>
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| 92 |
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| 93 | </sect2>
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| 94 |
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| 95 | <sect2><title>Short description</title>
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[2602f8d] | 96 |
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[673b0d8] | 97 | <indexterm zone="ch-system-MAKEDEV make_devices"><primary sortas="d-make_devices">make_devices</primary></indexterm>
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| 98 | <para id="make_devices"><command>make_devices</command> is a script for creating a basic set of
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| 99 | static device nodes, usually residing in the <filename class="directory">/dev</filename> directory.</para>
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| 100 |
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| 101 | </sect2>
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| 102 |
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| 103 |
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| 104 |
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| 105 | </sect1>
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