"Big Daddy Butthead" <noemail@yahoo.com> wrote in message
news:slrnbh1n14.cjo.noemail@news.easynews.com...
> I know how to enable dma on the harddisks manually. How can I do
> it first thing so that my bootup benefits from it?
>
> Another question, how can you enable dma for a cdrom? hdparm can't
> seem to do it.
>
> Thanks!

Enabling DMA on scsi-emulated IDE devices can be a bit of a problem.
I can think of two ways to do it. The first is to directly edit the values
in
/proc/ide/hdX/settings; where X is your specific device. I could never
get enough info to try this. The second requires that the
cdrom,ide-cd,sg,sr_mod and ide-scsi modules not be compiled
into the kernel and that the booloader does not enable scsi emulation.
A properly funcioning devfs is also needed. This also requires that these
modules not be loaded through modules.autoload(or elsewhere).In a startup
script you
might use something like the following:

hdparm -d1 /dev/hdX
rmmod cdrom
rmmod ide-cd
modprobe ide-scsi
modprobe sg
modprobe sr_mod

The general idea is to play with hdparm for the optical drives before
enabling
scsi emulation with ide-scsi. I am writing this from memory because I don't
have
access to the machines that I have done this procedure. I may be leaving out
some of the scsi modules that are needed but I hope that you get the general
idea

Steve.