Need help with CD burner

Bill Maltby LFS Related lfsbill at wlmcs.com
Thu Aug 22 03:38:30 PDT 2002


On Thu, 22 Aug 2002, Richard Lightman wrote:

> * Rob 'Feztaa' Park <feztaa at shaw.ca> [2002-08-22 06:40]:
> > 
> > Crap, I don't have any of those modules. What's this scsi jazz? I don't
> > have any scsi in my computer at all, it's all ide.

I just tested. To just load or eject the CD, modules cdrom and sr_mod are
not needed.

> > 
> The IDE command set is a bit limited. AFAIK, it is impossible to burn a
> CD with IDE commands.  This was solved a long time ago by the ATAPI
> protocol, which sends SCSI commands over an IDE bus.
> 
> Linux can access a CDROM with native IDE commands or with ATAPI SCSI
> commands. Mixing the two is possible, but it is simpler to choose just
> one method.

I use both, no problem. If you like to do both, to add IDE support, add
the below to what Richard shows. This is in (2.4.18 kernel) the same
section shown below:

  <*> Enhanced IDE/MFM/RLL disk/cdrom/tape/floppy support
  <m> Include IDE/ATAPI CDROM support

> Here are the modules you will need for a cd burner, and
> the ones that will just cause hassle:
> 
> ATA/IDE/MFM/RLL support  --->
>   IDE, ATA and ATAPI Block devices  --->
>     <*>   Include IDE/ATA-2 DISK support
>     < >   Include IDE/ATAPI CDROM support                                                                   
>     < >   Include IDE/ATAPI TAPE support                                                                    
>     < >   Include IDE/ATAPI FLOPPY support                                                                  
>     <M>   SCSI emulation support
> SCSI support  --->
>   <M> SCSI support
>     <M>   SCSI CD-ROM support
>     <M>   SCSI generic support
> 
> The vital one is SCSI generic support. The kernel does not know
> about CD burners. Instead, it allows SCSI commands to be sent from
> user space to scsi generic devices. Last time I checked, cdrecord
> was really bad about finding cd burners on linux. It is simplest
> to tell cdrecord where to look in /etc/defaults/cdrecord:
> 
> CDR_DEVICE=/dev/scsi/host0/bus0/target0/lun0/generic
> CDR_SPEED=1

Cdrecord helps if you do cdrecord -scanbus. Most often it will be
0,0,0 if you have no real SCSI in your system. If you are not running
devfs, your CDR_DEVICE will then be 0,0,0. The docs recommend this for
portability reasons. I'm not sure I agree.

> When say "writes CD's at x40", they are using marketing speak. To
> get old CDROMS to read cheap media reliably, reduce the speed.
> Speed 1 is the slowest speed supported by the drive - probably
> about x4 for a modern drive.
> 
> Lastly you need some stuuff in /etc/modules.conf
> 
> # Let modeprobe know what SCSI car you have:
> alias scsi_hostadapter ide-scsi
> 
> # For static device nodes (at a guess)
> alias char-major-21     sg
> 
> # For devfs:
> above sr_mod            sg
> 
> #This would be more sensible to devfs, but it did not work: 
> #alias /dev/scsi/*/generic sg

My modules.conf, supporting both looks like this

above sr_mod ide-scsi
above scsi_mod ide-scsi

This allows the scsi_host_adapter to be not aliased.

> 
> 
> RIchard
> -- 
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> 

Bill Maltby
billm at wlmcs.com

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