10.51. Udev-093

#### Cross-Compiled Linux From Scratch - Version 1.0.0rc2-x86_64-Pure64

### Chapter 10. Installing Basic System Software

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# 10.51. Udev-093

The Udev package contains programs for dynamic creation of device nodes.

## 10.51.1. Installation of Udev

Compile the package:

    make EXTRAS="extras/floppy extras/cdrom_id extras/firmware \
        extras/scsi_id extras/volume_id extras/ata_id extras/usb_id \
        extras/edd_id extras/dasd_id extras/path_id" udevdir=/dev

The meaning of the make parameter:

`EXTRAS="extras/floppy extras/cdrom_id extras/firmware extras/scsi_id extras/volume_id extras/ata_id extras/usb_id extras/edd_id extras/dasd_id extras/path_id"`

  This builds the helper applications that are used with udev. The helper programs assist in correct handling of devices.

If you want to run the testsuite, you need to change a hardcoded reference to the test program:

    sed -i 's@/usr/bin/test@/bin/test@' test/udev-test.pl

To test the results, issue: `make test`.

Install the package:

    make DESTDIR=/ \
        EXTRAS="extras/floppy extras/cdrom_id extras/firmware \
        extras/scsi_id extras/volume_id extras/ata_id extras/usb_id \
        extras/edd_id extras/dasd_id extras/path_id" udevdir=/dev install

The meaning of the make parameter:

`DESTDIR=/`

  This prevents the Udev build process from killing any udevd processes that may be running on the system.

Install necessary helpers.

    install -v extras/eventrecorder.sh /lib/udev

Install the documentation that explains how to create Udev rules:

    install -v -m644 -D docs/writing_udev_rules/index.html \
        /usr/share/doc/udev-093/index.html

Create a directory for storing firmware that can be loaded by udev:

    install -dv /lib/firmware

## 10.51.2. Contents of Udev

Installed programs: udevcontrol, udevd, udevinfo, udevmonitor, udevsend, udevtest, and udevtrigger
Installed directory: /etc/udev

### Short Descriptions

udevcontrol | Configures a number of options for the running udevd daemon, such as the log level.
udevd | A daemon that reorders hotplug events before submitting them to udev, thus avoiding various race conditions
udevinfo | Allows users to query the udev database for information on any device currently present on the system; it also provides a way to query any device in the `sysfs` tree to help create udev rules
udevmonitor | Prints the event received from the kernel and the event which udev sends out after rule processing
udevsettle | Watches the Udev event queue and exits if all current uevents have been handled
udevtest | Simulates a udev run for the given device, and prints out the name of the node the real udev would have created or (not in CLFS) the name of the renamed network interface
udevtrigger | Walks the sysfs tree for devices that need to be added to the system.
ata_id | Provides Udev with a unique string and additional information (uuid, label) for an ATA drive
cdrom_id | To be written
create_floppy_devices | Creates all possible floppy devices based on the CMOS type
firmware.sh | To be written
path_id | Provide the shortest possible unique hardware path to a device
scsi_id | To be written
vol_id | To be written
usb_id | To be written
edd_id | To be written
dasd_id | To be written
`/etc/udev` | Contains udev configuation files, device permissions, and rules for device naming
`/lib/udev` | Contains udev helper programs and static devices which get copied to /dev when booted.

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