> From: Wackojacko [mailto:[EMAIL PROTECTED] > Sent: Friday, September 23, 2005 5:56 AM
<...> > Googling this error (google is always your friend :) ) suggested that > > - you may want to turn DMA off for the drive ' hdparm -d0 /dev/hdc'. > May need to install 'hdparm' first. Ah, thanks for both the suggestion and the method. Mike McCarty privately suggested that I disable DMA for this drive, but I couldn't do it from BIOS and was unaware of this system utility. Thank you very much for bearing with me. This seems to fix the problem! It also uncovered another minor bug, but at least the system is usable. After disabling DMA on the CDROM, inserting a CD causes the file system to mount, a CD icon to appear on the gnome desktop and a Nautilus file browser opens showing the CD file system. To unmount the file system and unlock the CDROM eject button, close the file browser, right click on the CD desktop icon and hit eject. At that point, I get an error dialog that reports: Failed to start command (details: Failed to execute child process "eject" (No such file or directory)). However, the CD icon does then disappear from the desktop and the CDROM tray eject button becomes unlocked, so it did the job despite the error message. Directly unmounting the CD file system as root using umount /media/cdrom0 accomplishes the task without any error messages, though you shouldn't have to do this. So it appears that I have two bugs to report, one for the driver not being able to operate the drive with DMA enabled and another for the GUI error, though I am not certain what packages to report them under. Googling a bit further, as you suggested, shows that failure to mount CD's is not a new problem in Linux and some people have unsuccessfully tried to fix the root causes. I hope they are still trying. See https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=137831 This user had the same problem with both FC3 and FC4 and with certain builds, the problem was intermittent. Follow-up reports showed that it was a nasty interaction between haldaemon, DMA and the kernel itself. It was not fixed in the 2.6.12-1.1398_FC4 kernel, though they expected it to be. The root cause is thought to be some piece of code looking for information at the very end of a CD that is at a different location when the CD is not completely full. The DMA hangs waiting for the nonexistent data and things go downhill from there. The Fedora crew still hasn't solved this one, suggesting it is more complicated than that. I haven't figured out if it is limited to Joliet, Rock Ridge or plain ISO9660. The media I used were all Joliet and I don't believe that I have any other types around to try. Both CD writers that I own are on Windows machines, and they always write with Joliet format extensions. I would like to report the fact that the CDROM driver malfunctions with DMA enabled to the Debian bug tracker, and the eject GUI error as a separate bug, but I'm not sure what packages to list. After reading the Fedora discussion on this problem, it's not clear that anyone really knows which packages are at fault. I also wonder how to make this change permanent. I could put a call to hdparm in one of the init scripts, though I was hoping that /etc/fstab or some other configuration file might have a "nodma" option to set for that drive. I cannot find such an option in either the Debian reference or the man pages for fstab, mount, etc. I'm sure it exists somewhere, but I haven't been able to find it. The Debian reference shows a command called setcd in section 9.1.3, but it looks like it's meant for setting the default speed. The package page on setcd has no information on what it does. > > - hal (hardware extraction layer) deamon can cause this trouble so try > stopping haldeamon if installed. I didn't try this, but I bet it would work. It's not as good a workaround, though, as you would want to start it again each time you were done reading a CD. -- Seth Goodman -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
