enable dma

[Fred McFeeters]

Hello,
My name is Fred Mcfeeters. I have a P4 1.6 Running RedHat 7.3, and
I'm trying to get DMA enabled on my disk drives. I tried hdparm -d1
/dev/had and hdparm -d /dev/hdc and both return the same error:

"HDIO_SET_DMA: failed operation not permitted"

so I searched news groups and web sites including redhats and man pages.
And came up with using /etc/sysconfig/harddisks<device> so I made
(/etc/sysconfig/harddiskhda, /etc/sysconfig/harddiskhdc,
/etc/sysconfig/harddiskshda, /etc/sysconfig/harddiskshdc) all with the
command using_dma = 1. still no help, I have upgrade the hdparm package
and upgraded from 2.4.18-3 to the 2.4.18-5 still no luck.

Any thing you can suggest would be helpful thanks in advanced.