Lost CAM Access to DVD Writer

Thomas Schmitt scdbackup at gmx.net
Mon Sep 2 06:28:04 UTC 2013


Hi,

> I got the same result and error message as I did when trying to dump the
> file system

The question towards FreeBSD developers is therefore:

Why does device "/dev/cd0" with this gesture

      ... in_fd = open (device,O_RDONLY)) ...
      ... 
        if (ioctl (in_fd,CAMGETPASSTHRU,&ccb) < 0)

cause error ENOTTY, as indicated by growisofs message
  "Inappropriate ioctl for device"

Maybe it is necessary to write a small demo program,
because growisofs is kindof an anti-example of a clean
software architecture. (Well, a debugger should make
clear how it gets to the failed ioctl attempt.)

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The question towards the port maintainer of growisofs would be
whether there is interest to develop a workaround which avoids
that special ioctl. I would help, if desired.

A test with cdrskin as substitute for growisofs would demonstrate
whether this is worthwhile:
  /sbin/dump ... -P 'cdrskin -v dev=/dev/cd0 -eject -' ...
or
  dd if=/dev/zero bs=1M count=100 | cdrskin -v dev=/dev/cd0 -eject -

(We have some indication by success of cdrecord. But i am
 reluctant for social reasons to analyze the FreeBSD doings
 of cdrecord. Its author accuses others of stealing his code.)


I would further like to bring to the porter's attention a bug fix
for growisofs with blank BD-R media:
  http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=713016
Meanwhile well tested by users of Fedora.

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Have a nice day :)

Thomas



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