Re: Udev. Problems with ordering hardware using /dev/video

On 07/31/2007 12:47 PM, Nigel Henry wrote:
I've managed to resolve most of my problems on my own, but Udev has beaten me.

Sarge is not a problem, as it's using the 2.4.27, or 2.6.8 kernel, and Udev is not in the equation. Etch has a 2.6.8, and a 2.6.17 kernel, and Lenny has a 2.6.11, and a 2.6.17 kernel. The problem is with the 2.6.17 kernel that uses Udev.

My TV card was set as /dev/video0, and some time later the webcam was set as /dev/video1. this works fine with the pre 2.6.17 kernels (no Udev), and the TV card consistently is /dev/video0, and the webcam /dev/video1. Booting with the 2.6.17 kernel is a different scenario. Very hit and miss. Sometimes I boot up and starting Xawtv, I get the TV /dev/video0. Othertimes I bootup and start Xawtv, and get my webcam /dev/video1.

I've worked with ordering my soundcards, and the lines are quite simple, and have seen that something similar is possible with Udev, although the lines a re a bit more complex. Could someone give me a couple of lines so that my TV card is always /dev/video0, and the webcam is always /dev/video1?

Any help gratefully appreciated for fixing this annoying problem.

Nigel.




On my Etch system, I needed persistent devices, and I didn't want to learn udev, so I created a new directory for persistent device nodes (/prdev). In /prdev, I used mknod to make the nodes that I needed, and I configured the applications to use those nodes.

This may or may not work for you however. It seems that udev can deal with situations where devices don't have standard major and minor numbers, and some applications are hard-wired to use nodes in /dev (slap the programmers).

In my previous Debian installation, I wrote a startup script to create my device nodes in /dev (after udev had loaded), but this again depends upon there being major and minor numbers designated for the devices in question.




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