Difference between revisions of "Udev"
(udev from c) |
m (Caretaker: Format links, Format headings) |
||
| Line 1: | Line 1: | ||
[[Wikipedia:Udev|udev]] deals with hotplugging (and coldplugging) devices such as USB key drives, usb cameras and firewire drives. Cold-plugging means connecting or disconnecting a device while the host machine is powered off. | [[Wikipedia:Udev|udev]] deals with hotplugging (and coldplugging) devices such as USB key drives, usb cameras and firewire drives. Cold-plugging means connecting or disconnecting a device while the host machine is powered off. | ||
| − | ==Configuration== | + | == Configuration == |
udev takes messages from the kernel (2.6 onwards) and processes them in userland. The structure of the config file is very simple. It defines how you will bind kernel messages to actions by way of pattern matching. | udev takes messages from the kernel (2.6 onwards) and processes them in userland. The structure of the config file is very simple. It defines how you will bind kernel messages to actions by way of pattern matching. | ||
*[http://downloads.linuxfromscratch.org/ Lots of examples] | *[http://downloads.linuxfromscratch.org/ Lots of examples] | ||
| Line 37: | Line 37: | ||
== Resources == | == Resources == | ||
| − | |||
*[http://linux-hotplug.sourceforge.net/ Linux Hotplug project] | *[http://linux-hotplug.sourceforge.net/ Linux Hotplug project] | ||
*[http://lkml.org/lkml/2005/2/10/179 Best of all: Hotplug in C] | *[http://lkml.org/lkml/2005/2/10/179 Best of all: Hotplug in C] | ||
Revision as of 17:01, 2 November 2006
udev deals with hotplugging (and coldplugging) devices such as USB key drives, usb cameras and firewire drives. Cold-plugging means connecting or disconnecting a device while the host machine is powered off.
Configuration
udev takes messages from the kernel (2.6 onwards) and processes them in userland. The structure of the config file is very simple. It defines how you will bind kernel messages to actions by way of pattern matching.
Hotplugging and the Graphical User Interface
It is important to provide feedback to the user when they plug or unplug a device. It is suggested that both visual and audible feedback be provided where possible. The latency for plugging is about 1 second. For unplugging the response is almost immediate.
USB
This document may be useful Mounting and unmounting removable devices in linux
USB devices live at /proc/bus/usb. When a device is plugged this file is updated. Here is an example of the file:
T: Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2 B: Alloc= 0/900 us ( 0%), #Int= 0, #Iso= 0 D: Ver= 1.10 Cls=09(hub ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1 P: Vendor=0000 ProdID=0000 Rev= 2.06 S: Manufacturer=Linux 2.6.8-2-386 uhci_hcd S: Product=Intel Corp. 82801AA USB S: SerialNumber=0000:00:1f.2 C:* #Ifs= 1 Cfg#= 1 Atr=c0 MxPwr= 0mA I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub E: Ad=81(I) Atr=03(Int.) MxPS= 2 Ivl=255ms T: Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 6 Spd=12 MxCh= 0 D: Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1 P: Vendor=0d7d ProdID=1300 Rev= 0.50 S: Product=USB2.0 FlashDisk S: SerialNumber=1D4402000054 C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=200mA I: If#= 0 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=usb-storage E: Ad=81(I) Atr=02(Bulk) MxPS= 64 Ivl=0ms E: Ad=02(O) Atr=02(Bulk) MxPS= 64 Ivl=0ms
This computer has only one external USB device plugged in (USB2.0 FlashDisk). The other entry is the host controler (Intel Corp. 82801AA USB).
