Re: [gentoo-user] cdrecord - devname - was burning a dvd+r dl...

Dale <rdalek1967@×××××.com> wrote:

> > I am sorry for my bad English.
> > I used to run all my cdrecord commands as user. I am unable to run the
> > command in the format using dev=scsibus,target,lun as user (I can do so
> > as root), but I am able to burn a cd as user when using dev=/dev/cdrom.
> > With the first method the average write speed seems to be much faster
> > than with the second one.
> > I just wander if this is normal behavior. I always followed
> > http://gentoo-wiki.com/HOWTO_Create_a_DVD:Burn where it says:
> > "[snip]Replace /<device>/ with your dvd device (for example
> > /dev/dvd)[snip]" So the wiki seems to be wrong, isn't it?
> >
>
> Is the user you are attempting to run these commands as a member of the
> cd and cdrw groups?  Usually if a command works as root but not a user,
> it is a permissions problem which is fixed by being in the correct
> group.  I say usually.

Not true in the case of cdrecord.

The Linux kernel always needed root privs to burn media before 2004.
In 2004 a security bug was introduced that allowed to send any SCSI 
command to any drive.

In Autumn 2004 this bug was not fixed but the SCSI Linux kernel interface
was changed in an incompatible way. Now _some_ SCSI commands work as non-root.

SCSI is a try and error protocol and cdrecord checks which commands are working.
If it is possible to burn with the limuted non-root command set, it _may_ work
but there is a high risk for buffer underruns. In this case cdrecord believes 
that you own a really dumb burner that does not support most of the nice 
features....

Jörg

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