LinuxQuestions.org - /dev/cdrom is missing

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/dev/cdrom is missing

I'm using slackware 10, with 2.6.8.1, on a Sony Vaio laptop. In the past, I've never had problems with the cdrom. But I just installed MPlayer so I could watch DVDs, and I just noticed I have no /dev/dvd, no /dev/cdrom, and no /dev/hdc (the location of the cdrom according to dmesg (which doesn't seem to give me any errors concerning this issue but does show it as detected correctly). I'm rather new to linux, so I'm not exactly sure where else I can clue for clues on what could be wrong. I know its not a compatibility issue because 1. I installed this copy of slackware via cdrom and 2. I've played music from it in the past. I'm unable to find / -iname 'cdrom' anything that would seem to indicate the problem. Please advise?

Do you have the same probelm with 2.6.7? If not, go back to it or add it to lilo.

I currently don't have a 2.6.7 on this system. The default 2.4.26 kernel detects /dev/dvd (and else), but mplayer didn't work with it. I'm guessing that's a whole other ball of wax. But your suggestion doesn't actually solve the problem. If there's a reason the 2.6.8.1 won't work with my hardware, but 2.4.26 and 2.6.7 does, I would appreciate any explanation you can offer of why. Otherwise, I'd like to actually tackle the problem. If there's a problem with my kernel configuration (most likely) I'd like to actually fix the problem. Does anyone have any suggestion of how I can fix the issue?

Could you post your /etc/fstab file. It would appear that either the symlink has gone or something has made the relevant fstab line disappear.

Code:

/dev/hda3        swap            swap        defaults        0  0

/dev/hda4        /                reiserfs    defaults        1  1

/dev/hda6        /home            reiserfs    defaults        1  2

/dev/cdrom      /mnt/cdrom      iso9660    noauto,owner,ro  0  0

/dev/fd0        /mnt/floppy      auto        noauto,owner    0  0

devpts          /dev/pts        devpts      gid=5,mode=620  0  0

proc            /proc            proc        defaults        0  0

I don't have "/dev/pts extended attributes" compiles in... doing so now. Will post if it makes a difference.

When you tried to use the cd/dvd, was it mounted? The drive needs to be mounted to be seen by the program.

Also, go to www.untrepid.com and follow the link to Acidrip and from there go to the installation howto. There is a section on creating symlinks to your drives.

Is /dev/cdrom linked to the actual device ie. /dev/hdc ? If not you'll have to do that. Test it with

Code:

ls -la /dev/cdrom

If it's not linked do this:

Code:

ln -s /dev/hdc /dev/cdrom

Are you using ide-scsi emulation by any chance ?

*glances around* wow..
well ill just throw this out there, might give you a possible clue to more clues. Since you said its reported as hdc but you do not have a /dev/hdc node ( which i think is odd; but apparently the way nodes are handled in the 2.6 kernel is different & I haven't played around with it yet ) then I'm guessing maybe you dont have other irrevelant nodes? no no no. There must be a /dev/hdc. ls /dev and see, but if there REALLY isn't then I would look into how to create a node and assure it has to do with the 2.6 kernel as the process for handling nodes, as i've said, has changed. I remember seeing a good bit of material here on the forums long while past,

anyway if I were you I'd look into trying to create the node

ps: if you manage to create the node and reboot and it dissappears this means you did it the old way and not the 2.6 way :D

Adding the /dev/pts extended attributes did not chant anything obvious to me.

Quote:

When you tried to use the cd/dvd, was it mounted?

No, I thought I had remember reading somewhere that audio CDs did not need to be mounted, and THOUGHT I read that neither did DVD, plus the config in mplayer was pointed to /dev/dvd, and I don't know of a way to mount that (just mount from that).

[quote]The drive needs to be mounted to be seen by the program.[/q]
I will boot back into 2.4.26 and give that a try.

Quote:

Also, go to www.untrepid.com and follow the link to Acidrip

http://acidrip.thirtythreeandathird.net/ was not located. Maybe I just tried during a bad time. But, I had actually downloaded it from sourceforge to try it out last night, so I went back there, following the link to the homepage there, and found the documentation at http://www.jabentley.com/docs/acidrip-howto.html. That was just the same instruction posted above by eelriver...

Code:

ln -s /dev/hdc /dev/cdrom

I was a little bit unclear...

Code:

$ dmesg|grep hdc

    ide1: BM-DMA at 0x1868-0x186f, BIOS settings: hdc:DMA, hdd:pio

hdc: SONY CD-RW/DVD-ROM CRX820E, ATAPI CD/DVD-ROM drive

and

Code:

/dev$ ls

adsp@    fd0      hda4      mem        psaux@  stderr@  tty13@  tty22@  tty31@  tty40@  tty5@  tty59@  ttyS1@  vcs@    vcsa2@  vmnet3

agpgart@  fd1      hda5      misc/      ptmx    stdin@  tty14@  tty23@  tty32@  tty41@  tty50@  tty6@  ttyS2@  vcs1@  vcsa3@  vmnet4

audio@    fd2      hda6      mixer@    pts/    stdout@  tty15@  tty24@  tty33@  tty42@  tty51@  tty60@  ttyS3@  vcs2@  vcsa4@  vmnet5

console  fd3      hw_random  mouse@    radeon  tts/    tty16@  tty25@  tty34@  tty43@  tty52@  tty61@  ttyS4@  vcs3@  vcsa5@  vmnet6

core@    full    initctl|  null      random  tty      tty17@  tty26@  tty35@  tty44@  tty53@  tty62@  ttyS5@  vcs4@  vcsa6@  vmnet7

dri/      gpmctl=  input/    nvidia0    rtc    tty0@    tty18@  tty27@  tty36@  tty45@  tty54@  tty63@  ttyS6@  vcs5@  vcsa7@  vmnet8

dsp@      hda      kmem      nvidia1    shm/    tty1@    tty19@  tty28@  tty37@  tty46@  tty55@  tty7@  ttyS7@  vcs6@  vmmon  vmnet9

fb/      hda1    kmsg      nvidiactl  snd/    tty10@  tty2@  tty29@  tty38@  tty47@  tty56@  tty8@  urandom  vcs7@  vmnet0  zero

fb0@      hda2    log=      port      sonypi  tty11@  tty20@  tty3@  tty39@  tty48@  tty57@  tty9@  vc/      vcsa@  vmnet1

fd@      hda3    loop0      ppp        sound/  tty12@  tty21@  tty30@  tty4@  tty49@  tty58@  ttyS0@  vcc/    vcsa1@  vmnet2

Quote:

Are you using ide-scsi emulation by any chance ?

Actually, I originally was when I first noticed the problem. But since, I've re-compile the kernel without it. However, I was unable to remove "SCSI support", just the emulation. I'm not sure what I have selected elsewhere that's requiring scsi support, but I'll gladly find it and disable it if you think it would help and have any suggestions of what would be requiring it.

Quote:

I would look into how to create a node and assure it has to do with the 2.6 kernel as the process for handling nodesp

definitely intimidating, but I intend to know someday anyway, so I'll do some searching about... that would make sense... but then why was it working automatically when I was using 2.6.7. (it was working fine before I upgraded, i should have used the .config, but wanted to get more practice at compiling, and I didn't bother checking to make sure it was working because it didn't cross my mind until I went to use it)

Thanks for all of your suggestions. I've got some things to try, and I'll post again to share the results once I've had the chance.
BTW, get used to me. I always have the "odd" problems :( But I guess they're excellent learning experiences :)

Missing driver ?

I'dont think ide-scsi emulation has to be in kernel.

How did you set cd-rom support in kernel ? Isn't this driver compiled as module ?
Name of IDE cd-rom module is ide-cd so try to load it with /sbin/modprobe ide-cd and check if /dev/hdc (in your case) does appear.

Try this:

Code:

chmod +x /etc/rc.d/rc.udev

chmod +x /etc/rc.d/rc.hotplug

reboot

Does that fix it so that you have a /def/hdc? If so, you'll probably want to read up on udev and hotplug to get the symlinks all right.

Note that CD/DVD burning is busted in 2.6.8.1. 2.6.7 still works without SCSI emulation, though. Also, you are correct, you don't mount DVDs or CDs to play them.

I was unable to mount /dev/cdrom suddenly, through something I must have done stupidly. I am running kernel 2.6.7 (I hear so many complaints about 2.6.8.1) without scsi emulation. The chmod for hotplug and udev fixed it, so thank you very much shilo. Saved me a lot of research, and I would never have thought that that was the cause.

Thanks,
rich

Sorry it took so long for me to respond, I had a busy last couple of days. But, I was able to resolve the issue. The modprobe ide-cd fixed the problem. So I recompiled the kernel using(not as module) ide-cd("Include IDE/ATAPI CDROM support") . It does work now. Thanks to everyone who offered suggestions!

Can anyone explain to me what may have caused it to not detect the module automatically? Its a removable CD-ROM, so I would like to load it as a module, if possible. Does anyone have any suggestions of how I can have it autodetect whether the drive is there or not, and load accordingly?