Hi Bart,
Thanks for the notes on sdparm. I didn't know about that.
However, it was my system that found the dvd under /dev/scd0
John was trying to access it as /dev/hda.
Rob
________________________________
From: Bart Trojanowski <bart-oclug [ at ] jukie [ dot ] net>
To: Prof. John C Nash <nashjc [ at ] uottawa [ dot ] ca>; linux [ at ] lists [ dot ] oclug [ dot ] on [ dot ] ca
Sent: Sun, October 18, 2009 10:58:27 AM
Subject: Re: [OCLUG-Tech] dma in Ubuntu?
John,
hdparm is really meant for devices that are driven by ide and legacy ata
drivers. If your cdrom shows up as /dev/scd0, then it's going through a
subsystem of the Linux kernel that's responsible for SCSI. More
specifically you're driving your cdrom with "libata" SCSI layer that
makes IDE/ATA devices look like SCSI ones. Even though the device
accepts ATA commands, hdparm doesn't know how to talk to it because the
kernel didn't git it a device that looks like an ATA device.
You probably want to look at the sdparm and sg3-utils packages. Have a
look at this to learn more about sdparm:
http://sg.danny.cz/sg/sdparm.html
When I last had to use it, I found sdparm a lot harder to figure out
than the hdparm counter part. I don't have an ATA CDROM anywhere so I
was unable to actually generate the command you need to flip DMA on.
Should you end up using sdparm to get this going, I'd like to learn from
your success.
-Bart
--
WebSig: http://www.jukie.net/~bart/sig/
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