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Having trouble installing a piece of hardware? Want to know if that peripheral is compatible with Linux?
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I am trying to enable DMA mode on my dvd-rom to get enough speed to actually play a dvd. My drive supports DMA, so does the controller/motherboard, but I can get it to work. My HD is already running in DMA mode (set at startup), so I can't understand why the dvd doesn't work.
# hdparm -d1 /dev/dvd <-- As root, of course
/dev/dvd:
setting using_dma to 1 (on)
HDIO_SET_DMA failed: Operation not permitted
using_dma = 0 (off)
First off, try finding where /dev/dvd is pointing to:
ls -l /dev/dvd
Then, taking the actual device, try there:
hdparm -d1 /dev/hdX
If your device is using scsi emulation, determine which standard ide block device it was before emulation occured:
hda = Primary Master
hdb = Secondary Master
hdc = Primary Slave
hdd = Secondary Slave
Also, check the man page, it mentions using the -X option with -d option to ensure it uses the correct dma.
So
hdparm -d1 -X udma2 /dev/hdX
might be what you are looking for.
Do a search of the forums, I just noticed you are using RedHat and I recall there is a specific problem with enabling DMA on cdrom/dvdroms with RedHat, there's a setting you have to enter somewhere (I don't remember).
Thanks for the suggestion. I had no idea this problem was specific to rh-8.0. Here's what I found:
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I had the same problem. Here's the solution from Red Hat's web site:
NOTE: As with the 8.0 release, IDE DMA on CD-ROM drives is disabled by
default. If you are sure that your CD-ROM drive is capable of IDE
DMA, place the following line in the /etc/modules.conf file:
options ide-cd dma=1
I did it and now DVD is smooth as silk.
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