Bug 78718 - DMA does not work for DVD/CDROM drives with kernel-2.4.18-18.7.x.i686.rpm
DMA does not work for DVD/CDROM drives with kernel-2.4.18-18.7.x.i686.rpm
Product: Red Hat Linux
Classification: Retired
Component: kernel (Show other bugs)
i686 Linux
medium Severity medium
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Assigned To: Arjan van de Ven
Brian Brock
Depends On:
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Reported: 2002-11-28 02:50 EST by Eric Yeo
Modified: 2007-04-18 12:48 EDT (History)
0 users

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Fixed In Version:
Doc Type: Bug Fix
Doc Text:
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Last Closed: 2002-11-28 04:22:12 EST
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Description Eric Yeo 2002-11-28 02:50:00 EST
From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.0.1) Gecko/20021003

Description of problem:
kernel-2.4.18-18.7.x.i686.rpm appears to be compiled with DMA enabled for disks

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
Run "hdparm -d 1 /dev/hdc" where /dev/hdc is a DVD/CDROM drive.

Actual Results:  Hdparm has the following output
> /dev/hdc:
>  setting using_dma to 1 (on)
>  HDIO_SET_DMA failed: Operation not permitted
>  using_dma    =  0 (off)

Expected Results:  The DVD/CDROM drive should have DMA enabled.

Additional info:

This problem was seen in kernel-2.4.18-17.7.x.i686.rpm and
kernel-2.4.18-18.7.x.i686.rpm (recent updates).

DMA can be enabled with kernel prior to these ones.
Comment 1 Arjan van de Ven 2002-11-28 04:22:04 EST
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
Comment 2 Eric Yeo 2002-11-28 04:33:27 EST
That worked. Thanks. Perhaps the 7.3 documentation needs updating?
Comment 3 Leonard den Ottolander 2002-12-07 08:19:51 EST
Updating the docs is definitely a good idea.
And this extra flag in modules.conf seems a little redundant. DMA for CD drives
was already disabled by default and had to be enabled using harddiskhdx. Now
one will need to enable DMA for CD drives on 2 different places (at least on 7.x).
You are making it really hard to reenable DMA on CD drives. No need for that...

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