[Bug 149076] Re: I can't write a cd

hpp3 hpp3 at lavabit.com
Thu Apr 30 22:05:29 UTC 2009


After some research, I have come to the conclusion that this is a FEATURE, NOT a BUG, of WODIM. 
>From the wodim man page, concerning Process Scheduling Priority:

"Wodim tries to get higher process priority using different methods.
This is important because the burn process is usually a realtime task,
no long delays should occur while transmitting fresh data to the
recorder. This is especially important on systems with insufficient RAM
where swapping can create delays of many seconds.

A possible workaround on underpowered systems is the use of the burnfree
or similar feature, allowing the recorder to resume.

Root permissions are usually required to get higher process scheduling
priority.

On SVr4 compliant systems, wodim uses the real time class to get the
highest scheduling priority that is possible (higher than all kernel
processes). On systems with POSIX real time scheduling wodim uses real
time scheduling too, but may not be able to gain a priority that is
higher than all kernel processes.

In order to be able to use the SCSI transport subsystem of the OS, run
at highest priority and lock itself into core wodim either needs to be
run as root, needs to be installed suid root or must be called via RBACs
pfexec mechanism."


So, judging by the error logs everybody submitted, wodim is refusing to do the job because it needs permission to set memory limits. To do this, you either run wodim as root or set the SUID bit for /usr/bin/wodim and introduce potential security risks, OR...
Add this line to /etc/security/limits.conf:

@cdrom     -     memlock     unlimited

Just make sure you are part of the 'cdrom' group.
Apparently, some people are not affected by this because their particular setup is able to make use of the burnfree feature to avoid buffer underruns.
How to fix this distro-wide?
Dunno.

-- 
I can't write a cd
https://bugs.launchpad.net/bugs/149076
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