Date: Sun, 29 Sep 2002 03:41:30 +0200 (CEST) From: Anders Johansson <andjoh@cicada.linux-site.net> To: suse-linux-e@suse.com Subject: Re: [SLE] Linux CD-RW Driver?
Thomas Jones said:
Yes it is pointing to /dev/sr0. I didn't realize there was such a thing that used SCSI controllers to talk to IDE devices.
Yes, sadly. It's a pain, but for some reason it's necessary for things like cd recorders to be treated as scsi devices. Don't know why, but windows also does it, although it's slightly more transparent there.
It is documented on the web page of the developer of the cdrtools utilities: +++ README.ATAPI.gz People often ask me why do you depend on ATAPI-SCSI emulation, why don't you support generic IDE? Well first a statement: There is no single IDE burner out! Even a CD-ROM cannot be used decently if you use only IDE commands. Opening/closing the door, playing audio and similar things cannot be done using IDE commands - you will need SCSI commands to do this. But how do we do this with a drive that uses an IDE interface? The ATAPI standard describes method of sending SCSI commands over IDE with some small limitations to the "real" SCSI standard. For this reason ATAPI-SCSI emulation is the native method of supporting ATAPI devices. Just imagine that IDE is one of many SCSI transport mechanisms. This are some SCSI transports: - Parallel SCSI (what most people call SCSI) - SCSI over fiber optics - SCSI over IEEE 1394 (Fire Wire) - SCSI over USB - SCSI over IDE (ATAPI) As you now see, the use of the naming convention "ATAPI-SCSI emulation" is a little bit misleading. It should rather be called: "IDE-SCSI host adapter emulation" Some naming explanations: ATA Attachment Adapter IDE Integrated Drive Electronics (A Drive that includes ATA) ATAPI ATA Packet Interface When cdrecord has problems with ATAPI drives on Linux this usually is a Linux kernel problem. The Linux kernel maintainers unfortunately refuse to correct their current IDE driver system setup which does not support ATAPI by default. ATAPI _is_ SCSI over IDE transport. It is hard to understand why Linux still uses a standard driver setup that is designed for IDE CD-ROM drives made before 1994 (using a IDE compat mode that only allows to use the drive read-only) and does not handle to send SCSI commands to ATAPI drives by default. This makes it hard for people who just started with Linux to do CD-writing on Linux if they own an ATAPI drive. ++- For more info, have a look at "http://www.fokus.gmd.de/research/cc/glone/employees/joerg.schilling/private/..." -- Cheers, Carlos Robinson