Video devices

Hi: I have a webcam and a pvr350 capture card (modules pwc and ivtv resp) attached to my machine, running 2.6.16 kernel and udev. The classic problem is that these modules get assigned to /dev/video0 and /dev/video1 in seemingly arbitrary ways. I've tried forcing module loading at boot time but still can't seem to get one to load first consistently.

So, I turned to writing udev rules and followed the "writing udev rules" document. My goal would be to have udev just symlink

/dev/webcam0 to /dev/videoM

and

/dev/pvr0 to /dev/videoN,

where M and N are 0 and 1, assignmed however the system so chooses.

I've tried writing udev rules to symlink, but they didn't work. Upon further investigation I don't actually see any rules to create the video devices in the /etc/udev/rules.d/ directory. And yet, they are created. Also, I see they are mentioned in /etc/udev/devfs.rules, but there is no symlink to this file in the rules.d/ directory.

So, how do the video devices get created here? Is there some devfs left-over? Perhaps if I knew where the /dev/video?'s are being created I'd be able to figure out how to symlink to them?! I'm running debian unstable, fully updated.

Quoted 24 lines · Paul Check

Hi: I have a webcam and a pvr350 capture card (modules pwc and ivtv resp) attached to my machine, running 2.6.16 kernel and udev. The classic problem is that these modules get assigned to /dev/video0 and /dev/video1 in seemingly arbitrary ways. I've tried forcing module loading at boot time but still can't seem to get one to load first consistently.

So, I turned to writing udev rules and followed the "writing udev rules" document. My goal would be to have udev just symlink

/dev/webcam0 to /dev/videoM

and

/dev/pvr0 to /dev/videoN,

where M and N are 0 and 1, assignmed however the system so chooses.

I've tried writing udev rules to symlink, but they didn't work. Upon further investigation I don't actually see any rules to create the video devices in the /etc/udev/rules.d/ directory. And yet, they are created. Also, I see they are mentioned in /etc/udev/devfs.rules, but there is no symlink to this file in the rules.d/ directory.

Quoted 6 lines

So, how do the video devices get created here? Is there some devfs left-over? Perhaps if I knew where the /dev/video?'s are being created I'd be able to figure out how to symlink to them?! I'm running debian unstable, fully updated.

Udev does not need any rule to work, it just uses as the default the kernel device name and creates the node owned by root.

Kay

Quoted 34 lines · Kay Sievers

Quoted 24 lines · Paul Check

Hi: I have a webcam and a pvr350 capture card (modules pwc and ivtv resp) attached to my machine, running 2.6.16 kernel and udev. The classic problem is that these modules get assigned to /dev/video0 and /dev/video1 in seemingly arbitrary ways. I've tried forcing module loading at boot time but still can't seem to get one to load first consistently.

So, I turned to writing udev rules and followed the "writing udev rules" document. My goal would be to have udev just symlink

/dev/webcam0 to /dev/videoM

and

/dev/pvr0 to /dev/videoN,

where M and N are 0 and 1, assignmed however the system so chooses.

I've tried writing udev rules to symlink, but they didn't work. Upon further investigation I don't actually see any rules to create the video devices in the /etc/udev/rules.d/ directory. And yet, they are created. Also, I see they are mentioned in /etc/udev/devfs.rules, but there is no symlink to this file in the rules.d/ directory.

Quoted 6 lines

So, how do the video devices get created here? Is there some devfs left-over? Perhaps if I knew where the /dev/video?'s are being created I'd be able to figure out how to symlink to them?! I'm running debian unstable, fully updated.

Quoted 2 lines

Udev does not need any rule to work, it just uses as the default the kernel device name and creates the node owned by root.

Let me show what I did:

I created /etc/udev/local-late.rules containing:

KERNEL="ivtv", SYMLINK+="pvr0", GROUP="video"
KERNEL="pwc", SYMLINK+="webcam0", GROUP="video"

then created a symlink in /etc/udev/rules.d to that file:

z10_local-late.rules -> ../local-late.rules

and yet the /dev/webcam0 and /dev/pvr0 are not created.