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====== PLD udev FAQ (udev-0.71-5) ======


<file>From: Fryderyk Dziarmagowski <freetz>
To: pld-users-pl@lists.pld-linux.org
Subject: [FAQ] PLD udev FAQ
Date: Sun, 6 Nov 2005 21:59:31 +0100
X-Translated-By: Michał Łukaszek <prism>
</file>


===== Which kernel version is recommended for proper work of udev/udev-hotplug? =====
//Minimum recommended version is 2.6.12.x// (''udev'' ''hotplug'' won't work with the older) 



===== Udev doesn't load all modules =====
That's because it loads only modules for PCI devices that meet the requirements included in udev rules. That rules allow auto-loading feature only for internal USB devices (hubs), such as ''uhci-hcd'' or ''ehci-hcd''. 

If you want to get the modules of all devices loaded automatically, enable ''udevsynthetize'' in ''/etc/udev/udev.conf''. This is experimental and not fully tested though. 



===== What about hotplug? Will my pendrive work? =====
''hotplug'' included in current udev replaces the old ''hotplug'' completely. Parallel work of both is not recommended, so after ''udev'' is installed the old ''hotplug'' package is removed. 

USB pendrives will work like a charm if you read answer no. 1. 



===== I'd like to connect my digital camera/scanner/other USB device to my computer. Do I have to mount /proc/bus/usb with proper permissions? =====
Absolutely not. Install ''udev-digicam'' package, add yourself to the //digicam// group, and ''udev'''s agent will do the rest, no matter if the device is a scanner or another USB input device. 



===== Can udev automatically mount partitions or cd drives it finds? =====
While technically possible, ''udev'' is not designed to manage your ///etc/fstab// entries. There are specialized programs for this, like ''gnome-volume-manager''. 



===== I'm using nvidia-legacy and the /dev/nvidia* is not created! =====
That's a problem of ''nvidia'' (legacy) drivers. ''udev'' has nothing to do with it. Unfortunately, you must manually create proper device files using ''mknod''. 

You can make ''modprobe'' create these devices for you every time the ''nvidia'' module is loaded by adding the following line to your ///etc/modprobe.conf//: 



<file>install nvidia /sbin/modprobe --ignore-install nvidia && { mknod /dev/nvidia0 c 195 0; mknod /dev/nvidia1 c 195 1; mknod /dev/nvidia2 c 195 2; mknod /dev/nvidia3 c 195 3; mknod /dev/nvidiactl c 195 255; /bin/true; }
</file>
Note that this should be all in one line. 



===== Modules like psmouse and evdev are not loaded automatically =====
The kernel's input layer is broken. It's said to be fixed in 2.6.15. 



===== Do I have to add the usb-controller alias in /etc/modprobe.conf? =====
No. All ''*-hcd'' modules are loaded automatically. 



===== I get the error messages about failed agents in my system logs =====
They don't work because they are not there - unless you installed ''udev-digicam'', which has the usb agent. That udev warnings in logs don't look nice, but they are absolutely harmless. This will be fixed if there is a person willing to fix it. 



===== I've got a problem that is not covered here. How do I diagnose it? =====
Try the following: 


  - set ''udev_log'' to ''info'' in ///etc/udev/udev.conf// to improve verbosity of ''udev''; 
  - use ''udevmonitor'' (see ''man udevmonitor'') to get even more infomation from older udev; 
  - use  ''udevadm monitor'' (see 'man udevadm') to get even more infomation (udev-151) ; 
  - check the //linux-hotplug// list's archive at [[http://marc.theaimsgroup.com/?l=linux-hotplug-devel|http://marc.theaimsgroup.com/?l=linux-hotplug-devel]]. 


===== How can I increase udev logs verbosity =====
Try (udev-154): 

<file>udevadm control --log-priority=debug
</file>
And check results in '/var/log/daemon' 



===== How to test rule I have just written? =====
Reload rules: 

<file>udevadm control --reload-rules # (udev-151)
</file>
Trigger event (replug device) or trigger all events: 

<file>udevadm trigger  --verbose 
</file>
If still unsure, ask your question on PLD [[:MailingLists|mailing lists]]. 


 


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