CD-RW problems, yet again
 

Hi,

I've carefully read all others threads I could find on this topic; other than that, I tried Google (of course). Both, however, with no luck.

Since I wanted my CD-burner to, ehm, burn CD's, I followed the advice I got somewhere, and took care of having SCSI emulation in my kernel. I also put the line "append='hdc=ide-scsi'" in my lilo.conf, but I haven't tested burning some CD since, because I'm in some trouble with my CD-drive.

First, I can't figure out what my CD-drive is called with SCSI-emulation enabled. The problem is that I can't even try out with scd0, sr0 and what not, because I get errors all the time.

When I try "mount -t iso9660 /dev/scd0 /cdrom", I get "/dev/scd0 is not a valid block device". Same goes for scd1 and sr0, which made me check my dmesg. There, I found this error, reported about a dozen times:

ide-scsi: hdc: unsupported command in request queue (0)
end_request: I/O error, dev 16:00 (hdc), sector 64
isofs_read_super: bread failed, dev=16:00, iso_blknum=16, block=32

These are the lines I searched for with Google, but, as I said, without any solutions... I also found this error on this forum, but also without any usable advice. I must say I'm quite desperate. Burning CD's (accessing them at all, actually) is the last thing I'm having problems with; other than that, everything just works as it did when I still used Windows.

Please be kind, I'm just a newbie. And many many thanks in advance...

Tom

I dont have a straight forward solution but just some suggestions. Do you have SCSI CD or SCSI generic support enabled in the kernel?
I'm sure someone else will be able to help out more than me...
-NSKL

Piece by piece and yet another question, are you sure that your CD-burner is /dev/hdc? Does ide-scsi module show up in /sbin/lsmod ? and post the output of /sbin/lsmod as well, it might help us to narrow the problem down.

Yes. That's at least *something* I'm sure of... :-/

Er... The module does not show up in lsmod. Lsmod actually mentions only *one* module, which is the Nvidia-driver.

Concerning the question about the kernel of the previous poster: I actually managed to compile my own kernel, and it works, and I'm sure I enabled SCSI-emulation support. But how do I check right now if it is SCSI CD or SCSI generic support?

Thanks for your help; it's much appreciated.

Tom

SCSi-emulation and SCSI CD / generic support are three different things.
SCSI emulation is needed to make /dev/hdc look like a SCSI device while SCSI generic and CD support are needed to actually talk to that device ones SCSI-emulation is working.
You should be able to enable SCSI generic / CD support under the SCSI section of make menuconfig.
Anyways, it seems your scsi emulation module is not loaded. Did you compile it as a module or statically into the kernel when you recompiled your kernel?
-NSKL

Hey, I really should've found these forums earlier; I've never had such fast replies...

About the SCSI support: when I have a look at my kernel config (with make menuconfig), "SCSI disk support" and "SCSI generic support" are checked (built-in, not as a module).

Thx,
Tom

And you also have compiled in SCSI emulation support in /ide/ata/atapi block devices section of menuconfig?
If so then you should be pretty much set.
Add append="hdd=ide-scsi"
at the end of your kernel stanza in /etc/lilo.conf (NOTE, for you should be hdc=ide-scsi)
Then save the file, and run lilo so the new changes take effect.
Now restart and try to mount your CD with mount /dev/sr0 /mnt or mount /dev/scd0 /mnt and it SHOULD work.

I'm basically telling you all that you already know ain't i? But sometimes it's better to do something again if you are not sure, just in case that you maybe forgot something the first time.
So try it again, and if it STILL doesn't work post any messages mount gives you, look through dmesg, and in /var/log/messages and /var/log/syslog
HTH
-NSKL

post the output of:

ls /proc/scsi

Yes.

Yes :D, but that's okay.

Right. First off, I should perhaps mention that I had a line in my /etc/fstab for automounting my cd-drive, back when it was still a regular IDE-drive. I removed that line, and rebooted. Here goes.

josmansbos:/home/tom# mount -t iso9660 /dev/scd0 /cdrom
mount: /dev/scd0 is not a valid block device
josmansbos:/home/tom#

Same goes for /dev/sr0 and /dev/sg0...

In dmesg, I find the error I already posted in my original question, though I'm not sure if it isn't *still* the error from when I tried ripping the CD, this morning.

[Iide-scsi: hdc: unsupported command in request queue (0)
end_request: I/O error, dev 16:00 (hdc), sector 0
isofs_read_super: bread failed, dev=16:00, iso_blknum=16, block=3260[/I]

/var/log/messages reports the exact same thing, without the first line. Same goes for /var/log/syslog, which also reads "modprobe: modprobe: Can't locate module block-major-11", but I'm not sure what that's supposed to mean, or if it is relevant here (I didn't do something involving modprobe).

And @moses:

josmansbos:/home/tom# ls /proc/scsi
ide-scsi scsi sg
josmansbos:/home/tom# cd /proc/scsi/ide-scsi/
josmansbos:/proc/scsi/ide-scsi# ls -a
. .. 0
josmansbos:/proc/scsi/ide-scsi# file 0
0: empty
josmansbos:/proc/scsi/ide-scsi# cd ..
josmansbos:/proc/scsi# file scsi
scsi: empty

I'd like to thank you guys once again. I'm really desperate. If I can't get my cd-rw to work, I'm afraid I'll have to go back to Win**ws, which is *absolutely* not what I want... :(

Tom

just out of curiousity, this may sound dumb..

have you tried mounting a different CD, preferably one that's not blank.

Ok, your ide-scsi support is in the kernel. (/proc/scsi/ide-scsi will only
show up if it's supported by the kernel). So, now we have to find that
device.
post the output from:

cat /proc/scsi/scsi
cat /proc/scsi/ide-scsi/0

@lopezjo49: Alas, I *did* try different CD's, with no luck.

@moses:

tom@josmansbos:~$ cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
Vendor: LITE-ON Model: LTR-40125W Rev: WS05
Type: CD-ROM ANSI SCSI revision: 02
tom@josmansbos:~$ cat /proc/scsi/ide-scsi/0
SCSI host adapter emulation for IDE ATAPI devices
tom@josmansbos:~$

Thx a lot,
Tom

Ok, so the device exists. Do you happen to know if you run devfs?

It's pretty easy to tell:

ls /dev/scsi

If there is an error, you're not running devfs, if you see something like:
host0
you have devfs, and it's really simple to find your CD, just follow the
directory tree down to:
/dev/scsi/host0/bus0/target0/lun0/cd
this is your CD, and you can mount with the command:
mount /dev/scsi/. . ./cd /mnt

However, I get the feeling you aren't running devfs, so it's going to take
a little more detective work to find your drive. . .

run:
dmesg | grep -i scsi
post that

Another thing you can try (assuming you are running LILO), is adding
change your /etc/lilo.conf "append=hdX=ide-scsi" line:

append="hdX=ide-scsi ide=nodma"

If your harddrive needs DMA, you can use your startup scripts to turn
it back on using hdparm (man hdparm).

Hm. I've never seen this approach before, but alas, it seems I'm not running devfs.

... gives me this:

tom@josmansbos:~$ dmesg | grep -i scsi
Kernel command line: BOOT_IMAGE=Linux ro root=301 hdc=ide-scsi
ide_setup: hdc=ide-scsi
SCSI subsystem driver Revision: 1.00
scsi0 : SCSI host adapter emulation for IDE ATAPI devices
Type: CD-ROM ANSI SCSI revision: 02
ide-scsi: hdc: unsupported command in request queue (0)
ide-scsi: hdc: unsupported command in request queue (0)
ide-scsi: hdc: unsupported command in request queue (0)
ide-scsi: hdc: unsupported command in request queue (0)
ide-scsi: hdc: unsupported command in request queue (0)
ide-scsi: hdc: unsupported command in request queue (0)

...those lines being part of the error I mentioned in a previous post. But again, I don't know when these errors occured.


Thx a lot again,
Tom

I've never seen this error, but you may have to disable (or enable) DMA.

What kernel (version numbers) are you running?