how-to debug udev
 

I want to use udev to give specific names to two mice.
My system runs Ubuntu 12.10 and I have an old system running Ubuntu 10.04 which is already doing this (so I am using it as a reference).

/etc/udev/rules.d/90-wally.rules contains:
KERNEL=="event[0-9]*", ATTR{idVendor}=="047d", ATTR{idProduct}=="1020", MODE="0664", GROUP="plugdev", NAME="input/trackBallBig"
KERNEL=="event[0-9]*", ATTR{idVendor}=="047d", ATTR{idProduct}=="1022", MODE="0664", GROUP="plugdev", NAME="input/trackBallSmall"

lsusb shows:
Bus 001 Device 005: ID 047d:1022 Kensington Orbit Optical
Bus 001 Device 006: ID 047d:1020 Kensington Expert Mouse Trackball

ls -l /dev/input shows (relevant parts):
crw-r----- 1 root root 13, 32 Jan 4 17:10 mouse0
crw-r----- 1 root root 13, 33 Jan 4 17:10 mouse1
crw-r----- 1 root root 13, 34 Jan 4 17:10 mouse2

Looking at the 10.04 machine, ls -l /dev/input shows (relevant parts):
crw-r----- 1 root root 13, 32 2012-11-28 16:44 mouse0
crw-r----- 1 root root 13, 33 2012-12-15 10:51 mouse1
crw-r----- 1 root root 13, 34 2012-11-28 16:44 mouse2
crw-rw-r-- 1 root plugdev 13, 68 2012-11-28 16:44 trackBallBig
crw-rw-r-- 1 root plugdev 13, 67 2012-12-15 10:51 trackBallSmall

I have confirmed that udev daemon is running and that the group plugdev exists. I don't find any errors in syslog. Earlier I had some errors, but then discovered that "SYSFS" keyword in rules file needs to be "ATTR".

In /var/log/udev I find no references to "trackBall*", whereas on the 10.04 machine, I see "DEVNAME=/dev/input/trackBallSmall".

I am stuck for what to do to debug this. Are my rules incorrect for what I want to do? I have read the udev tutorial http://ubuntuforums.org/showthread.php?t=168221 but need additional help.

thanks

You can use "udevadm" command to help. For example this command show what kernel sees and which udev rules was triggered after connecting deviceMaybe changing name is not supported. Try to create symlink (by SYMLINK=="input/trackBallBig" rule) instead of changing kernel name (NAME=...)

thanks, the following rules (from /etc/udev/rules.d/90-trackball.config) worked.

#try this based on output of "udevadm monitor --kernel --udev --property"
# 01/15/13 THIS WORKS the devices themselves are in plugdev group with crw-rw-r-- perms
# BEST SET OF RULES SO FAR. DO NOT DELETE.
#SUBSYSTEM=="usb", ATTR{product}=="Kensington Expert Mouse", MODE="0664", GROUP="plugdev", SYMLINK+="input/trackBallBig"
#SUBSYSTEM=="usb", ATTR{product}=="Kensington USB/PS2 Orbit", MODE="0664", GROUP="plugdev", SYMLINK+="input/trackBallSmall"

#tried this just to see and IT WORKS. This is better than the best because there are no symlinks
SUBSYSTEM=="usb", ATTR{product}=="Kensington Expert Mouse", MODE="0664", GROUP="plugdev", NAME="input/trackBallBig"
SUBSYSTEM=="usb", ATTR{product}=="Kensington USB/PS2 Orbit", MODE="0664", GROUP="plugdev", NAME="input/trackBallSmall"