lfs-book/chapter06/hotplug.xml

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<sect1 id="ch-system-hotplug" xreflabel="Hotplug" role="wrap">
<title>Hotplug-&hotplug-version;</title>
<?dbhtml filename="hotplug.html"?>

<indexterm zone="ch-system-hotplug"><primary sortas="a-Hotplug">Hotplug</primary></indexterm>

<sect2 role="package"><title/>
<para>The Hotplug package contains scripts that react upon hotplug events
generated by the kernel. Such events correspond to every change in the kernel
state visible in the <systemitem class="filesystem">sysfs</systemitem>
filesystem, e.g., the addition and removal of hardware. This package also
detects existing hardware during boot and inserts the relevant modules into the
running kernel.</para>

<segmentedlist>
<segtitle>&buildtime;</segtitle>
<segtitle>&diskspace;</segtitle>
<seglistitem><seg>0.01 SBU</seg><seg>460 KB</seg></seglistitem>
</segmentedlist>

<segmentedlist>
<segtitle>&dependencies;</segtitle>
<seglistitem><seg>Bash, Coreutils, Find, Gawk, and Make</seg></seglistitem>
</segmentedlist>
</sect2>

<sect2 role="installation">
<title>Installation of Hotplug</title>

<para>This package does not come with a test suite.</para>

<para>Install the Hotplug package:</para>

<screen><userinput>make install</userinput></screen>

<para>Copy a file that the <quote>install</quote> target omits.</para>

<screen><userinput>cp -v etc/hotplug/pnp.distmap /etc/hotplug</userinput></screen>

<para>Remove the init script that Hotplug installs since we are going to be
using the script included in the LFS-Bootscripts package:</para>

<screen><userinput>rm -rfv /etc/init.d</userinput></screen>

<para>Network device hotplugging is not yet supported by the LFS-Bootscripts
package. For that reason, remove the network hotplug agent:</para>

<screen><userinput>rm -fv /etc/hotplug/net.agent</userinput></screen>

<para>Create a directory for storing firmware that can be loaded by
<command>hotplug</command>:</para>

<screen><userinput>mkdir -v /lib/firmware</userinput></screen>

</sect2>


<sect2 id="contents-hotplug" role="content"><title>Contents of Hotplug</title>

<segmentedlist>
<segtitle>Installed program</segtitle>
<segtitle>Installed scripts</segtitle>
<segtitle>Installed files</segtitle>
<seglistitem><seg>hotplug</seg>
<seg>/etc/hotplug/*.rc, /etc/hotplug/*.agent</seg>
<seg>/etc/hotplug/hotplug.functions, /etc/hotplug/blacklist, /etc/hotplug/{pci,usb},
/etc/hotplug/usb.usermap, /etc/hotplug.d, and /var/log/hotplug/events</seg></seglistitem>
</segmentedlist>

<variablelist><bridgehead renderas="sect3">Short Descriptions</bridgehead>
<?dbfo list-presentation="list"?>
<?dbhtml list-presentation="table"?>

<varlistentry id="hotplug">
<term><command>hotplug</command></term>
<listitem>
<para>This script is called by default by the Linux kernel when something
changes in its internal state (e.g., a new device is added or an existing device
is removed)</para>
<indexterm zone="ch-system-hotplug hotplug"><primary
sortas="b-hotplug">hotplug</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="hotplug-rc">
<term><command>/etc/hotplug/*.rc</command></term>
<listitem>
<para>These scripts are used for cold plugging, i.e., detecting and acting upon
hardware already present during system startup. They are called by the
<filename>hotplug</filename> initscript included in the LFS-Bootscripts package.
The <command>*.rc</command> scripts try to recover hotplug events that were lost
during system boot because, for example, the root filesystem was not mounted by
the kernel</para>
<indexterm zone="ch-system-hotplug hotplug-rc"><primary
sortas="d-/etc/hotplug/*.rc">/etc/hotplug/*.rc</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="hotplug-agent">
<term><command>/etc/hotplug/*.agent</command></term>
<listitem>
<para>These scripts are called by <command>hotplug</command>
in response to different types of hotplug events generated by the kernel.
Their action is to insert corresponding kernel modules and call any
user-provided scripts</para>
<indexterm zone="ch-system-hotplug hotplug-agent"><primary
sortas="d-/etc/hotplug/*.agent">/etc/hotplug/*.agent</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="hotplug-blacklist">
<term><filename>/etc/hotplug/blacklist</filename></term>
<listitem>
<para>This file contains the list of modules that should never be inserted into
the kernel by the Hotplug scripts</para>
<indexterm zone="ch-system-hotplug hotplug-blacklist"><primary
sortas="e-/etc/hotplug/blacklist">/etc/hotplug/blacklist</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="hotplug-functions">
<term><filename>/etc/hotplug/hotplug.functions</filename></term>
<listitem>
<para>This file contains common functions used by other scripts in the Hotplug
package</para>
<indexterm zone="ch-system-hotplug hotplug-functions"><primary
sortas="e-/etc/hotplug/hotplug.functions">/etc/hotplug/hotplug.functions</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="hotplug-subdirs">
<term><filename class="directory">/etc/hotplug/{pci,usb}</filename></term>
<listitem>
<para>These directories contain user-written handlers for hotplug events</para>
<indexterm zone="ch-system-hotplug hotplug-subdirs"><primary
sortas="e-/etc/hotplug/{pci,usb}">/etc/hotplug/{pci,usb}</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="hotplug-usb.usermap">
<term><filename>/etc/hotplug/usb.usermap</filename></term>
<listitem>
<para>This file contains rules that determine which user-defined handlers to
call for each USB device, based on its vendor ID and other attributes</para>
<indexterm zone="ch-system-hotplug hotplug-usb.usermap"><primary
sortas="e-/etc/hotplug/usb.usermap">/etc/hotplug/usb.usermap</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="hotplug-hotplug.d">
<term><filename class="directory">/etc/hotplug.d</filename></term>
<listitem>
<para>This directory contains programs (or symlinks to them) that are interested
in receiving hotplug events. For example, Udev puts its symlink here during
installation</para>
<indexterm zone="ch-system-hotplug hotplug-hotplug.d"><primary
sortas="e-/etc/hotplug.d">/etc/hotplug.d</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="hotplug-firmware">
<term><filename class="directory">/lib/firmware</filename></term>
<listitem>
<para>This directory contains the firmware for devices that need to have their
firmware loaded before use</para>
<indexterm zone="ch-system-hotplug hotplug-firmware"><primary
sortas="e-/lib/firmware">/lib/firmware</primary></indexterm>
</listitem>
</varlistentry>

<varlistentry id="hotplug-events">
<term><filename>/var/log/hotplug/events</filename></term>
<listitem>
<para>This file contains all the events that <command>hotplug</command> has
called since bootup</para>
<indexterm zone="ch-system-hotplug hotplug-events"><primary
sortas="e-/var/log/hotplug/events">/var/log/hotplug/events</primary></indexterm>
</listitem>
</varlistentry>

</variablelist>
</sect2>
</sect1>