how to use cdrecord

Roland Smith rsmith at
Sun Mar 14 09:08:57 UTC 2010

On Sun, Mar 14, 2010 at 11:47:35AM +0800, Aiza wrote:
> Chris Hill wrote:
> > On Sun, 14 Mar 2010, Aiza wrote:
> > 
> > [snip]
> >> tried cdrecord -v speed=2 dev=acd0 blank=fast
> >> gives this error "Open by devname not supported on this OS.
> >>
> >> What device am i to use?
> > 
> > cdrecord wants to see your ATA burner as a SCSI device, so you'd use
> >   cdrecord dev=1,0,0 ...
> > The numbers after dev= depend on where your burner is; find it using
> >   cdrecord -scanbus
> > 
> > HTH.
> > 
> cdrecord -scanbus gives a error. Invalid argument. Camiocommand ioctl 
> failed, can not open scsi driver

You need SCSI emulation for your burner in your kernel. Specifically, you need
to recompile your kernel with the following devices in its configuration file:

    device          atapicam        # emulate ATAPI devices as SCSI ditto via CAM
                                    # needs CAM to be present (scbus & pass)
    # SCSI peripherals
    device          scbus           # SCSI bus (required for SCSI)
    device          da              # Direct Access (disks)
    device          cd              # CD
    device          pass            # Passthrough device (direct SCSI access)

See the manual pages atapicam(4), scbus(4), cd(4) and pass(4).

It could be that these devices are also available as modules, but I've always
build a custom kernel, so I don't know about that. The manual pages don't say
that they are available as modules, so I'm inclined to say they are not.

After rebuilding the kernel, which you'll find documented in Chapter 8 of the
Handbook, you also need to give your user-id write access to the right
devices. I have done that by creating a group "cdrom", to which I've added my
user-id (with 'pw groupmod -m'). Then I've put the following lines in my

    # Give members of group cdrom access to the CD/DVD-ROM and DVD+RW via the
    # SCSI interface
    own     xpt0    root:cdrom
    perm    xpt0    0660
    own     cd0     root:cdrom
    perm    cd0     0660
    own     cd1     root:cdrom
    perm    cd1     0660
    link    cd1     cdrom
    link    cd1     dvd

Since I've got both a burner and a regular DVD player in my machine, you see
two cd devices but only one xpt device.

Additionally, the following has been added to my standard ruleset in /etc/devfs.rules:

    add path 'pass*' mode 0660 group cdrom

And in /etc/rc.conf the following is added;


I've put the pass device in devfs.rules because it will attach to every SCSI
device that attaches to the system, _even if they are added after booting_
like e.g. USB disks used with the da(4) driver.

Hope this helps.

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