# Problem with CDRW drives, SCSI emulation and devfs

## Tarball

Hi,

In my machine I have a DVD-Rom drive and a CDRW drive.

DVD-Rom  -   /dev/hdb

CDRW      -   /dev/hdc

During boot the IDE-SCSI module loads and displays the following:

--------- 8< snip 8< -----------------

SCSI subsystem driver Revision: 1.00

scsi0 : SCSI host adapter emulation for IDE ATAPI devices

  Vendor: LG        Model: DVD-ROM DRD8160B  Rev: 1.00

  Type:   CD-ROM                             ANSI SCSI revision: 02

  Vendor: SONY      Model: CD-RW CRX1611     Rev: TYS3

  Type:   CD-ROM                             ANSI SCSI revision: 02

Attached scsi CD-ROM sr0 at scsi0, channel 0, id 0, lun 0

Attached scsi CD-ROM sr1 at scsi0, channel 0, id 1, lun 0

sr0: scsi3-mmc drive: 0x/48x cd/rw xa/form2 cdda tray

Uniform CD-ROM driver Revision: 3.12

sr1: scsi3-mmc drive: 40x/40x writer cd/rw xa/form2 cdda tray

--------- 8< snip 8< -----------------

Yet when the system is loaded, the devices in /dev/... are:

/dev/hdb (DVD)  -   /dev/scsi/host0/bus0/target1/lun0/cd

/dev/hdc (CDRW)-   /dev/scsi/host0/bus0/target0/lun0/cd

and therefore:

/dev/hdb (DVD) has symlinks:     /dev/sr1 & /dev/sg1

/dev/hdc (CDRW) has symlinks:   /dev/sr0 & /dev/sg0

But if I run 'cdrecord -scanbus' it produces the following:

natty ~ # cdrecord -scanbus

Cdrecord 1.11a24 (i686-pc-linux-gnu) Copyright (C) 1995-2002 Jörg Schilling

Linux sg driver version: 3.1.22

Using libscg version 'schily-0.6'

scsibus0:

        0,0,0     0) 'LG      ' 'DVD-ROM DRD8160B' '1.00' Removable CD-ROM

        0,1,0     1) 'SONY    ' 'CD-RW CRX1611   ' 'TYS3' Removable CD-ROM

        0,2,0     2) *

        0,3,0     3) *

        0,4,0     4) *

        0,5,0     5) *

        0,6,0     6) *

        0,7,0     7) *

So, if I am trying to use 'gtoaster' to write a CD I select the second drive as the writer (the Sony drive, dev=0,1,0) but when gtoaster tries to actually write to dev=0,1,0 it seems to be the DVD drive that is accesses (and obviously fails!)

Any ideas what is going on??  I've only had the problem since moving to Gentoo but then this is the first time I have used devfs.

All the IDE-SCSI stuff is compiled into the kernel.

Cheer.

----------------------------------

Abit BP6 MoBo (2x 466 Celerons)

640MB RAM

1x10GB Maxtor drive, 1x40GB Maxtor

Abit Siluro GeForce 3 Ti200

LG DVD-ROM drive

Sony CDRW drive.

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## smtanner

What happens if you physically reverse the drives on your motherboard:

hdb = cdrw

hdc = dvd

Do you still have the same problem?

I know that is not the best solution but for lack of anything else.

What do you have attached as hda?

Anything attached as hdd?

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## Tarball

I haven't tried reversing the drives.

On hda I have a 10GB Maxtor HD and there is nothing on hdd.  

The only gripe I have about reversing the DVD and CDRW drives is that the CDRW drive would have to be a slave.

At the moment I have the SCSI emulation stuff compiled into the kernel.  I am gonna recompile the stuff as modules then I can try playing around with it on the command-line.

How are the devices 'realised' by devfs.  Is it just a first come first served basis???

Cheers.

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## smtanner

Not sure how devices are itialized with devfs.

Try disabling devfs to see what happens.  In grub, use the line devfs=nomunt.  I think it is the same in lilo.  If this fixes your problem, then it would seem to be a bug in devfs.

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