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udev and DVD/CD RW under debian unstable

Sat, 2005-02-12 15:18 — chris

To get CD and DVD burning running under debian unstable on a 2.6.x kernel

Under 2.6 ide-scsi (SCSI emulation) is deprecated. It's recommended to use ide-cd instead. Using ide-cd under debian will also correctly set up sysfs details to help you get udev to auto-create the correct devices.

So - first make sure you're using ide-cd. This means - make sure you remove ide-scsi from lilo.conf (not sure about grub), and then check /etc/modules. It should contain the line ide-cd and not ide-scsi.

Secondly, the udev packages have done the work required to get udev to recognise the devices.

udev processes the rules files in /etc/udev/rules.d in alphanumeric order. If you use the non-devfs naming style (which I prefer) the file /etc/udev/udev.rules is symlinked into /etc/udev/rules.d.

In /etc/udev there is also a file called cd-aliases.rules. To get the aliases for CDROM, CDRW, DVD, DVDRW all you need to do is to symlink this into rules.d.

So, as root (or use sudo)


# cd /etc/udev/rules.d
# ls -l
lrwxrwxrwx 1 root root 13 2004-10-15 12:51 udev.rules -> ../udev.rules
# ln -s ../cd-aliases.rules .
# ls -l
lrwxrwxrwx 1 root root 13 2004-12-18 12:12 udev.rules -> ../cd-aliases.rules
lrwxrwxrwx 1 root root 13 2004-10-15 12:51 udev.rules -> ../udev.rules

Restarting udev will (since the ide-cd module is loaded) find the correct info in sysfs (/sys) to correctly generate devices.

For example on my home box:


$ ls -l /dev/cd*
lrwxrwxrwx 1 root root 3 2005-01-20 19:45 /dev/cdrom -> hdc
lrwxrwxrwx 1 root root 3 2005-01-20 19:45 /dev/cdrom1 -> hdd
lrwxrwxrwx 1 root root 3 2005-01-20 19:45 /dev/cdrw -> hdd

And it's identified hdc and hdd correctly so that they are members of the cdrom group.

One issue with this is that cdrecord and dvdrecord even with using dev=ATAPI seem to want the generic scsi devices too. I've not looked into this too much, so it could be just a config error, but for DVD burning I tend to use growisofs since this talks direct to the ide device.

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