Hardened Linux From Scratch - Version SVN-20070501

Chapter 6. Installing Basic System Software

6.46. Hotplug-2004_09_23

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 sysfs 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.

6.46.1. Installation of Hotplug

Remove the installation of the init script provided by Hotplug, since we're going to be using the script included with LFS-Bootscripts. This command removes 3 lines (a mkdir, a chmod, and an install): 

sed -e '/init.d/d' -i Makefile

Network device hotplugging is not supported by LFS-Bootscripts yet. For that reason, prevent the installation of the network hotplug agent: 

mv etc/hotplug/net.agent etc/hotplug/net.agent.unsupported

Install the Hotplug package: 

make install

Copy a file that the “install” target omits. 

install -m644 etc/hotplug/pnp.distmap /etc/hotplug

6.46.2. Contents of Hotplug

Installed program: hotplug
Installed scripts: /etc/hotplug/*.rc, /etc/hotplug/*.agent
Installed files: /etc/hotplug/hotplug.functions, /etc/hotplug/blacklist, /etc/hotplug/{pci,usb}, /etc/hotplug/usb.usermap, /etc/hotplug.d

Short Descriptions

hotplug

This script is called by default by Linux kernel when something changes in its internal state (e.g., a new device is added or removed).

/etc/hotplug/*.rc

These scripts are used for cold plugging, i.e., detection and other specific actions upon hardware already present during system startup. They are called by the hotplug initscript that comes from the LFS-Bootscripts package. The *.rc scripts try to recover hotplug events that were lost during system boot because, e.g., the root filesystem was not mounted by the kernel.

/etc/hotplug/*.agent

These scripts are called by hotplug in response to different types of hotplug events generated by the kernel. Their action is to insert corresponding kernel modules and call user-provided scripts, if any.

/etc/hotplug/hotplug.functions

This file contains common functions used by other scripts in Hotplug package.

/etc/hotplug/blacklist

This file contains the list of modules that should never be inserted into the kernel by hotplug scripts.

/etc/hotplug/{pci,usb}

These directories are supposed to contain user-written handlers for hotplug events.

/etc/hotplug/usb.usermap

This file contains rules that determine which user-defined handlers to call for each USB device, based on its vendor, id and other attributes.

/etc/hotplug.d

This directory contains programs (or symlinks to them) that are interested in receiving hotplug events. E.g., Udev puts its symlink here during installation.