UDev + USB Storage Device

Bralkein · 2004-10-26 16:16:48

Hello,

Firstly I would like to say that I have been using Arch Linux for a while now, and it is the best distro I have ever used. I would say it is halfway between Debian and Slackware, which is pretty much exactly what I wanted!

I have a problem, however, and I was just wondering if anyone could please spare the time to help me.

I recently switched my system to use UDev. I did this using the guide in the Wiki, and it seems like it is all going well except for one small thing. When I plug in my mp3 player, which basically works exactly like a USB hard disk drive in terms of transferring files, a device node is not created under the /dev directory... or if it is, I cannot find it! I even have this problem if I boot up with the device plugged in.

Now I know that the device is detected properly, because when I plug it in, the correct kernel module (usb_storage) is loaded. I can see it with lsmod. I can also see all the device information in the file /proc/bus/usb/devices. As far as I know, the kernel module is loaded by hotplug, so presumably a hotplug event is generated, which should, as I understand things, cause udevd to create a device node based on the udev.rules file. This does not happen.

Back in the dark (yet USB-Storage friendly) days of DevFS, the device was located under the node /dev/sda, so I assumed that this was the kernel name for the device. I added the line:

KERNEL="sda*", NAME="%k"

in an attempt to make the device node be generated. Alas, this was to no avail, still no device node! I tried another line, which I was sure must catch the device if it were present:

BUS="usb", NAME="%k"

but once again, the node is missing.

Does anyone know what I am doing wrong here? Maybe one of these things is the answer:

1) Perhaps I am missing a required kernel module, I do not know. I am using a custom 2.6.9 kernel, does anybody know the minimum kernel options required for usb storage support? I would have thought it was just usb_storage, but I am no expert.

2) Perhaps I have made an error in writing the udev.rules file, but I do not know where the error could be.

Well whatever it is, please help me! Thanks in advance.

linfocito · 2004-10-26 17:38:27

Probably your personal user have no permissions on the sda devs.

Just add your user to the group "disk", and (I think) your USB storage dev will work again.

Egil.B · 2004-10-26 17:44:27

Perhaps you are looking for the wrong file. My usb-devices changed from sd* to ub* after a kernel-upgrade.

phrakture · 2004-10-26 17:52:20

I may be totally wrong here - but i thought udev used the long named version - similar to /dev/discs/disc/disc0 or soemthing regardless of scsi/ide....

dp · 2004-10-26 20:33:11

phrakture wrote:

I may be totally wrong here - but i thought udev used the long named version - similar to /dev/discs/disc/disc0 or soemthing regardless of scsi/ide....

as far i know, /dev/discs/disc/disc0 is devfs, but we have it in archlinux for compatiblity reasons ... you can set permissions the way you want them to be

since usb-storage is now ub, it is not longer under scsi NOR ide ... and i don't think, someone set /dev/ud* -> /dev/discs/ rules for udev in arch

Stanislav · 2004-10-26 20:41:16

maybe this one will help you!

http://bbs.archlinux.org/viewtopic.php?t=7560

Bralkein · 2004-10-29 18:07:19

Ah, thanks very much! Yes, apparently having the usb_storage module is just not enough, you need to compile in the SCSI disk drivers too. I don't know why this is, and I don't know why it isn't automatically selected when you select usb_storage, but there you go. That's just how it bes. You know I didn't think that the SCSI thing could be the cause, because I read somewhere that you no longer need it for USB disk support, but I think they were probably getting it all confused with not needing SCSI for CD-writing. Anyway, it all works fine now! Plug it in, device node created. Pull it out, device node goes away. Hurrah! UDev is the coolest.

Thanks again for your help.

Arch Linux

#1 2004-10-26 16:16:48

UDev + USB Storage Device

#2 2004-10-26 17:38:27

Re: UDev + USB Storage Device

#3 2004-10-26 17:44:27

Re: UDev + USB Storage Device

#4 2004-10-26 17:52:20

Re: UDev + USB Storage Device

#5 2004-10-26 20:33:11

Re: UDev + USB Storage Device

#6 2004-10-26 20:41:16

Re: UDev + USB Storage Device

#7 2004-10-29 18:07:19

Re: UDev + USB Storage Device

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