Frank Scheiner wrote:
> as my Ultra 10 has a CDROM drive installed
> instead of a DVDROM drive I was mislead to write "CDROM drive"

"DVD" gives a hint of the age of the drive. Everything from this century
should be driven by SCSI commands (volumes SPC, SBC, MMC).

There must have been old days when cdrecord needed special "drivers"
for particular CD burners (see man cdrecord, option driver=) and libcdio
was founded to unify the access to CD reader models on GNU/Linux.

> But interestingly the assumed same controller driver works well for Gregor's
> and my Ultra 10 and it also works well when Fred uses a CDROM drive.
> What could be the reason for that?

Oops. While lurking i missed that report from Fred.
(I am here because my libisofs packs up the ISOs. But this thread i watch
with my libburn hat on.)

About twenty to fifteen years ago, when DVD drives came up for PCs, there
was no problem to attach them where CD drives were plugged before.

The fact that it works for the firmware and GRUB (i assume) quite outrules
that the controller would be unwilling to talk to the drive.

Fred wrote:
> The HP DVD drive was in use on a U5 running Wheezy and worked fine.

At least Jessie's kernel 3.16 looks much like
https://github.com/torvalds/linux in respect to optical drives. So i doubt
that it is about a kernel change. What kernel version does the Wheezy
machine have ?

Can it be the DVD drive is at the edge of failure ?
Does it still work in the U5 ? Is the plug loose or dusty ?

When it is in the problem machine and the installer was exited to a shell
prompt, is there a device file /dev/sr0 ?
I flatly assumed that there is none. Better check.

Is a system log availabe of the installer system ?
Does it tell anything about the DVD drive or its IDE socket ?

Frank Scheiner wrote:
> [   36.327225] ata2.00: ATAPI: SAMSUNG DVD-ROM SD-616Q, F401, max UDMA/33
> [   36.465435] scsi 1:0:0:0: CD-ROM            SAMSUNG  DVD-ROM SD-616Q F401
PQ: 0 ANSI: 5
> [   36.926295] sr 1:0:0:0: [sr0] scsi3-mmc drive: 16x/48x cd/rw xa/form2
cdda tray
> [   37.023810] cdrom: Uniform CD-ROM driver Revision: 3.20
> [   37.098287] sr 1:0:0:0: Attached scsi CD-ROM sr0

That's what to look for in Fred's system log.

IDE, ATA, ATAPI specific drivers are out of my knowledge scope, i fear.
I only work on SCSI transaction level.

The first "scsi" message stems probably from Linux source file
and reports parts of the reply data of SCSI command INQUIRY.
This command reply is supposed to identify the device as Peripheral Device
Type 5 "MMC". drivers/scsi/scsi.c array scsi_device_types[5] bears the
text "CD-ROM". This selects the "sr" driver to take care of the device.

The "sr" message stems from drivers/scsi/sr.c. It reports the content of
Mode Page 0x2A "CD/DVD Capabilities and Mechanical Status Page".
If this inquiry fails, the kernel is supposed to report "scsi-1 drive"
and to go on with registering the drive, nevertheless.

The "cdrom" message stems from drivers/cdrom/cdrom.c function
register_cdrom(), probably called from sr.c function sr_probe(), which
finally reports the line about "Attached scsi CD-ROM".

It would be interesting to see when Fred's machine and DVD drive deviate
from this successful path.

> So actually any support for UltraDMA in the DVDROM or CDROM drive does not
> seem to make a difference.

I dimly remember that PIO was too lame for early DVD drives on PCs.
"hdparm -d" was needed in the init scripts.
But the (IIRC hardcoded) drive device files were usable. Just slow
and choking the HDD at the other IDE master socket. (2 x 2 IDE was normal
for a PC back then.)

Have a nice day :)


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