Need help with CD burner

Rob 'Feztaa' Park feztaa at shaw.ca
Thu Aug 22 10:24:15 PDT 2002


Alas! Richard Lightman spake thus:
> * 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.
> 
> 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.

Well, learn something every day, I guess ;)

But how does an IDE device understand SCSI commands?

> 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. 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

Whoa, thanks. Think you could print up something like that for full USB
support, including mice and NetMD walkmans? ;)

> 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

devfs, I take it? Well, I'm building a new LFS today, so I'm gonna give
that a shot (I'm too lazy to just recompile the kernel when what I
really want is a new LFS *anyway*).

> CDR_SPEED=1
> 
> 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.

Well that's no problem for me. I'm moving into university in about 9
days, and I'll easily have acres of class/sleep time for my burner to be
burning things.

> 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

Thanks, I'll fiddle with it ;)

-- 
Rob 'Feztaa' Park
http://members.shaw.ca/feztaa/
--
Hacking's just another word for nothing left to kludge.
-- 
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