[RndTbl] Re: CD-RW installation

Gilles Detillieux grdetil at scrc.umanitoba.ca
Wed Jan 15 13:23:36 CST 2003

According to Gilbert E. Detillieux:
> According to Mel Seder:
> > My son-in-law is running Red Hat and 8.0 and he connected a CD RW drive.
> > 
> > What steps do I have to take to get the drive working in linux?
> First, add the following line to the /etc/modules.conf file...
> alias scsi_hostadapter ide-scsi
> Then, you need to build an "initrd" file for your kernel, to load the
> ide-scsi driver automatically on system restart.  Check your kernel version

Actually it doesn't need to be half that complicated.  Since Red Hat 7.x,
the installer automatically checks for a CD-RW drive, and if found, it
will add the appropriate kernel boot command line option for enabling
ide-scsi support, e.g. "hdc=ide-scsi".  You can always add this manually
after the fact, if the CD-RW drive is only installed later, but you need
this kernel command line option whether you bother with the initrd stuff
or not.  In /etc/grub/grub.conf, you just add it to the kernel command
line.  If you use LILO, you have to add it via an append="hdc=ide-scsi"
line in /etc/lilo.conf, and then rerun "lilo".

The initrd stuff isn't needed, though.  All that's needed is for the
/etc/rc.d/* files to do the necessary modprobes to load the ide-scsi
drivers.  Red Hat 7 & 8 do this with the following commands in rc.sysinit:

# If they asked for ide-scsi, load it
if grep -q "ide-scsi" /proc/cmdline ; then
	modprobe ide-cd >/dev/null 2>&1
	modprobe ide-scsi >/dev/null 2>&1

For Red Hat 6, you can just add these to rc.local.  The line in
/etc/modules.conf is only needed if you make the initrd.

The other thing you may want to do is update the /dev/cdrom symlink so
it points to the new device (usually scd0) rather than hdc or hdd:

ln -fs scd0 /dev/cdrom

If your system has both CD-ROM and CD-RW drives, it's just slightly
more complicated.  With the older 2.2 kernels, if ide-scsi remapped the
CD-RW drive, it remapped the CD-ROM drive too, regardless of whether you
indicated both drive mappings on the kernel command line.  I don't know if
that's still the case in 2.4, but I don't think it hurts to do that too.
Generally the CD-RW should be the master (hdc) and will be mapped to scd0,
while the CD-ROM as slave (hdd) will be mapped to scd1.

Gilles R. Detillieux              E-mail: <grdetil at scrc.umanitoba.ca>
Spinal Cord Research Centre       WWW:    http://www.scrc.umanitoba.ca/
Dept. Physiology, U. of Manitoba  Winnipeg, MB  R3E 3J7  (Canada)

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