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SubjectRe: ide-scsi, ide cdwriter
Kenneth wrote:
> I'am trying to get my plextor IDE cd-writer to function in write mode
> but I have some ploblems.
> kernel version is 2.4.0-test7-pre5 and Cdrecord 1.8.
> The drive is detected by the ide-scsi
> scsi0 : SCSI host adapter emulation for IDE ATAPI devices
> scsi : 1 host.
> Vendor: PLEXTOR Model: CD-R PX-W8432T Rev: 1.05
> Type: CD-ROM ANSI SCSI revision: 02
> Detected scsi CD-ROM sr0 at scsi0, channel 0, id 0, lun 0
> Vendor: PIONEER Model: DVD-ROM DVD-104F Rev: 2.02
> Type: CD-ROM ANSI SCSI revision: 02
> Detected scsi CD-ROM sr1 at scsi0, channel 0, id 1, lun 0
> scsi : detected 2 SCSI cdroms total.
> sr0: scsi3-mmc drive: 32x/32x writer cd/rw xa/form2 cdda tray
> Uniform CD-ROM driver Revision: 3.11
> sr1: scsi3-mmc drive: 0x/0x cd/rw xa/form2 cdda tray
> But when "cdrecord -scanbus" tries to open the sg device to scan the bus
> none is working.
> A regular mount of sr0 or sr1 works OK.
> I have never tried using a cd writer under linx before so I don't know
> how it's supposed to work but this looks like some type of kernel bug to
> me.

"cdrecord -scanbus" tries to open /dev/sg0, /dev/sg1 ...
to see if there is a cdwriter hiding behind one of them.
Given what you have written above [which can also be seen
by 'cat /proc/scsi/scsi'] cdrecord either couldn't find
the file names /dev/sg0,1,2 (etc.) or it couldn't find
the sg driver.

Now if you are running devfs without installing devfsd
with a reasonable /etc/devfsd.conf configuration it is
possible that there are no files named /dev/sg0,1,2 etc.

After running 'cdrecord -scanbus' have a look at
$ cat /proc/devices
Character devices:
1 mem
2 pty/m%d
3 pty/s%d
4 tts/%d
5 cua/%d
7 vcs
10 misc
21 sg
128 ptm

If a line with "21 sg" ain't there then the sg driver
hasn't been loaded as a module (or wasn't build into the
kernel). If the sg driver is a module and those device
file names are in place then the attempt that cdrecord
makes to read those device names should load the sg

> ps. is not the scsi system a bit to easy ? I mean after two three hours
> you almost get it. we have sd sg st scd nst devices that I could find
> all with interesting indexing, The concept of naming a device d: lookes
> in comparison like a stroke of genius.

Sarcasm born out of frustration?

If you want to see the sg device number to SCSI
device [and pseudo device as in the case of IDE
cdwriters connected to the ide-scsi device]
mapping try:
$ cat /proc/scsi/sg/device_strs
IBM DNES-309170W SA30
YAMAHA CRW4416S 1.0g

To see the sg device number to SCSI host,channel,
id and lun mapping try:
$ cat /proc/scsi/sg/device_hdr /proc/scsi/sg/devices
host chan id lun type bopens qdepth busy
1 0 0 0 0 4 63 0
2 0 2 0 5 0 4 0
2 0 6 0 5 0 4 0

Doug Gilbert
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