1 | <?xml version="1.0" encoding="ISO-8859-1"?>
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2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
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3 | "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
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4 | <!ENTITY % general-entities SYSTEM "../general.ent">
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5 | %general-entities;
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6 | ]>
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7 |
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8 | <sect1 id="ch-system-devices">
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9 | <?dbhtml filename="devices.html"?>
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10 |
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11 | <title>Populating /dev</title>
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12 |
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13 | <indexterm zone="ch-system-devices">
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14 | <primary sortas="e-/dev/">/dev/*</primary>
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15 | </indexterm>
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16 |
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17 | <sect2>
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18 | <title>Creating Initial Device Nodes</title>
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19 |
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20 | <para>When the kernel boots the system, it requires the presence of a few
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21 | device nodes, in particular the <filename class="devicefile">console</filename>
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22 | and <filename class="devicefile">null</filename> devices. The device nodes
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23 | will be created on the hard disk so that they are available before
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24 | <command>udev</command> has been started, and additionally when Linux is
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25 | started in single user mode (hence the restrictive permissions on
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26 | <filename class="devicefile">console</filename>). Create the devices by
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27 | running the following commands:</para>
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28 |
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29 | <screen><userinput>mknod -m 600 /dev/console c 5 1
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30 | mknod -m 666 /dev/null c 1 3</userinput></screen>
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31 |
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32 | </sect2>
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33 |
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34 | <sect2>
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35 | <title>Mounting tmpfs and Populating /dev</title>
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36 |
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37 | <para>The recommended method of populating the <filename
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38 | class="directory">/dev</filename> directory with devices is to mount a
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39 | virtual filesystem (such as <systemitem class="filesystem">tmpfs</systemitem>)
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40 | on the <filename class="directory">/dev</filename> directory, and allow the
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41 | devices to be created dynamically on that virtual filesystem as they are
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42 | detected or accessed. This is generally done during the boot process. Since
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43 | this new system has not been booted, it is necessary to do what the
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44 | LFS-Bootscripts package would otherwise do by mounting <filename
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45 | class="directory">/dev</filename>:</para>
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46 |
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47 | <screen><userinput>mount -nvt tmpfs none /dev</userinput></screen>
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48 |
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49 | <para>The Udev package is what actually creates the devices in the <filename
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50 | class="directory">/dev</filename> directory. Since it will not be installed
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51 | until later on in the process, manually create the minimal set of device nodes
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52 | needed to complete the building of this system:</para>
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53 |
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54 | <screen><userinput>mknod -m 622 /dev/console c 5 1
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55 | mknod -m 666 /dev/null c 1 3
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56 | mknod -m 666 /dev/zero c 1 5
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57 | mknod -m 666 /dev/ptmx c 5 2
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58 | mknod -m 666 /dev/tty c 5 0
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59 | mknod -m 444 /dev/random c 1 8
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60 | mknod -m 444 /dev/urandom c 1 9
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61 | chown -v root:tty /dev/{console,ptmx,tty}</userinput></screen>
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62 |
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63 | <para>There are some symlinks and directories required by LFS that are
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64 | created during system startup by the LFS-Bootscripts package. Since this
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65 | is a chroot environment and not a booted environment, those symlinks and
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66 | directories need to be created here:</para>
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67 |
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68 | <screen><userinput>ln -sv /proc/self/fd /dev/fd
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69 | ln -sv /proc/self/fd/0 /dev/stdin
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70 | ln -sv /proc/self/fd/1 /dev/stdout
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71 | ln -sv /proc/self/fd/2 /dev/stderr
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72 | ln -sv /proc/kcore /dev/core
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73 | mkdir -v /dev/pts
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74 | mkdir -v /dev/shm</userinput></screen>
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75 |
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76 | <para>Finally, mount the proper virtual (kernel) file systems on the
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77 | newly-created directories:</para>
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78 |
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79 | <screen><userinput>mount -vt devpts -o gid=4,mode=620 none /dev/pts
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80 | mount -vt tmpfs none /dev/shm</userinput></screen>
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81 |
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82 | <para>The <command>mount</command> commands executed above may result
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83 | in the following warning message:</para>
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84 |
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85 | <screen><computeroutput>can't open /etc/fstab: No such file or directory.</computeroutput></screen>
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86 |
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87 | <para>This file—<filename>/etc/fstab</filename>—has not
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88 | been created yet but is also not required for the file systems to be
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89 | properly mounted. As such, the warning can be safely ignored.</para>
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90 |
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91 | </sect2>
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92 |
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93 | </sect1>
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