| 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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| 6 | <sect1 id="ch-system-devices" xreflabel="devices">
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| 7 | <title>Populating /dev with device nodes</title>
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| 8 | <?dbhtml filename="devices.html"?>
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| 9 |
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| 10 | <indexterm zone="ch-system-devices"><primary sortas="a-Devices">Devices</primary></indexterm>
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| 11 |
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| 12 | <sect2>
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| 13 | <title>Creating initial device nodes</title>
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| 14 |
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| 15 | <para>When the kernel boots the system, it requires the presence of a few device
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| 16 | nodes, in particular the console and null devices:</para>
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| 17 |
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| 18 | <screen><userinput>mknod -m 600 /dev/console c 5 1
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| 19 | mknod -m 666 /dev/null c 1 3</userinput></screen>
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| 20 | </sect2>
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| 21 |
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| 22 | <sect2>
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| 23 | <title>Mounting ramfs and populating /dev</title>
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| 24 |
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| 25 | <para>The ideal way to populate /dev is to mount a ramfs onto /dev (like tmpfs, but it
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| 26 | cannot be swapped) and create the devices on there during each bootup. Since we haven't
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| 27 | booted the system, we have to do what the bootscripts would otherwise do for us, and
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| 28 | populate /dev ourselves. Begin by mounting /dev:</para>
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| 29 |
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| 30 | <screen><userinput>mount -n -t ramfs none /dev</userinput></screen>
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| 31 |
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| 32 | <para>Now use the provided udevstart utility to create the initial devices based on
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| 33 | all the information in /sys:</para>
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| 34 |
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| 35 | <screen><userinput>/tools/sbin/udevstart</userinput></screen>
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| 36 |
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| 37 | <para>There are some symlinks and directories required by LFS that are not created by
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| 38 | Udev, so we create those ourselves here:</para>
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| 39 |
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| 40 | <screen><userinput>ln -s /proc/self/fd /dev/fd
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| 41 | ln -s /proc/self/fd/0 /dev/stdin
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| 42 | ln -s /proc/self/fd/1 /dev/stdout
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| 43 | ln -s /proc/self/fd/2 /dev/stderr
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| 44 | ln -s /proc/kcore /dev/core
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| 45 | mkdir /dev/pts
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| 46 | mkdir /dev/shm</userinput></screen>
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| 47 |
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| 48 | <para>Finally, mount the proper virtual (kernel) file systems on the directories we just
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| 49 | created:</para>
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| 50 |
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| 51 | <screen><userinput>mount -t devpts -o gid=4,mode=620 none /dev/pts
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| 52 | mount -t tmpfs none /dev/shm</userinput></screen>
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| 53 | </sect2>
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| 54 |
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| 55 |
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| 56 | </sect1>
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