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Agenda

Traditional UNIX h/w support

UDEV HAL What's next ???

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Devices on UNIX

UNIX isolates user and applications fromhardware.

Under UNIX almost every hardware device treated

as a file (Device file).

Device file allows software to interact with devicedriver using standart system calls.

/dev directory contains device files.

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Devices on UNIX

Device files: Character devices. Relate to devices throughwhich the system transmits data one characterat a time.

/dev/ttyS0 Block devices. Relate to devices through which

the system moves data in the form of blocks. /dev/sdao Pseudo devices. Do not have correspond

physical devices. /dev/null

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Devices on UNIX

Each device file has major and minor numbers. Major number identifies the device driver.

Minor number identifies a particular device.

brw-r----- 1 root disk 8, 0 14 2008 hdabrw-r----- 1 root disk 8, 1 14 2008 hda1crw-rw---- 1 root uucp 4, 64 14 2008 ttyS0crw-rw---- 1 root uucp 4, 65 14 2008 ttyS1

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Devices on UNIX

How to create device file ?mknod filename [b] [c] major minor

How to find major number ?/proc/devices- list of character and block devices

sorted by major number

Minor number ???Depends on particular driver.

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Static /dev issues

Two many device files

Deficiency of the major and minor numbers

Ambiguity

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devfs

devfs is a specific implementation of a devicefile system on Unix-like operating systems,used for presenting device files.

Totally in kernel.

Present on Linux till 2.6.15

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UDEV

udev - userspace device management

udev provides a dynamic device directory containingonly the files for actually present devices.

Runs as a daemon udevd

udev creates device files according to naming rules./lib/udev/rules.d (/etc/udev/rules.d/)

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UDEV

Receives directly from the kernel using netlinkinterface.

Uses sysfs (/sys directory) to get device attributes.

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UDEV

How to write naming rule file?

There are two kind of keys, match and assignment keys.

Examples:KERNEL=="sd[0-9]*",NAME="flash/%n"

KERNEL=="sd[a-z]",PROGRAM="check_cd.sh %M %m",

NAME="%c{1}", SYMLINK="cdrom"

KERNEL=="lp*", SUBSYSTEMS=="usb",

ATTRS{idVendor}=="03f0", ATTRS{product}=="hp

LaserJet 1000", SYMLINK+="hplj1000-%n", RUN+="/

usr/sbin/hplj1000"

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D-Bus

A message bus system (IPC)

Language independent (C/C++, Python,

Perl, etc)

Simple way for applications to talk to one

Provides a system and session bus

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D-Bus

Acts as a user-space daemon (bus).

Bus types: system session

Message types: Method calls Responces

Signals

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D-Bus

Service(Application) are found by nameorg.gnome.Rhytmbox

A service can export multiple objects/org/gnome/Rhytmbox

Each object implements at least one interfaceorg.gnome.Rhythmbox.Player

Interface provides methods

next()

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HAL

Hardware Abstraction Layer for UNIX-likesystems.

A library for enumerating the physical hardware in a

system

A toolkit for enumerating the physical and logicaldevices in a system

A platform for discovering and configuring hardware

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HAL

HAL is a daemon responsible for discovering,enumerating and access to hardware on thecomputer.

It aims to allow desktop applications to discover anduse the hardware of the host system through asimple, portable and abstract API

Applications communicate with HAL through theD-Bus IPC mechanism.

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HAL

On a formal level, a device object is comprised by UDI

This is an identifier, the Unique Device Identifer, that is uniquefor a device object , no other device object can have the same UDIat the same time. Properties

Each device object got a set of properties which are key/valuepairs. The key is an ASCII string while the value.

UDI = '/org/freedesktop/Hal/devices/disk1'|---block.device /dev/sda1

|---block.is_volume 1|---info.capabilities volume,block|---volume.label WORK `|---volume.uuid 0717-AD77

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HAL

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HAL

Device Information Files (.fdi files) - mechanismfor associating information with devices.

How to use HAL ? DBUS

libHal

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HAL hardware management overview

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HAL is in maintenance mode - no newfeatures are added.

All future development focuses on Software/DeviceKit-disks Software/DeviceKit-power

NetworkManager PulseAudio udev

HAL Deprecation.

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DeviceKit

DeviceKit a better HAL

Designed to deliver same features as HALProvide a D-Bus based APIParallel installable with HAL

Another DBUS objectorg.freedesktop.DeviceKit

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DeviceKit

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Storage Subsystem Daemon

DeviceKit-disks Consumes udev information Started on demand

High-level API w/ progress reporting

DeviceKit-disks

Mount, Unmount, Eject, Poll, FsckPartitioning, Formatting, FS LabelATA SMART monitoring

MD-RAID (Create, Start/Stop, Check, )Drive spindown

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DeviceKit-disks

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Comments ???