Red Hat Bugzilla – Bug 78718
DMA does not work for DVD/CDROM drives with kernel-2.4.18-18.7.x.i686.rpm
Last modified: 2007-04-18 12:48:45 EDT
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 only. Version-Release number of selected component (if applicable): How reproducible: Always 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.
https://rhn.redhat.com/errata/RHSA-2002-206.html 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
That worked. Thanks. Perhaps the 7.3 documentation needs updating?
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...