How to setup DMA on my CD-RW?
Paul W. Frields
paul at frields.com
Tue Oct 7 00:51:13 UTC 2003
On Mon, 2003-10-06 at 20:07, Thiago Vinhas de Moraes wrote:
> > > Does anyone how to do it?
> >
> > IIRC (this has changed a number of times), you have to make a
> > /etc/sysconfig/harddisk<device> file that contains USE_DMA=1,
> > where <device> is the device of your disk or CD-ROM (such as hdc).
>
> At least on Fedora beta2, there is only the /etc/sysconfig/harddisks
> file. You are right, there is the USE_DMA option, but it will set DMA
> ON to all the hard disks. Is this a problem?
The /etc/sysconfig/harddisks file is a global settings file that can be
overridden by separate files such as /etc/sysconfig/harddiskhda,
/etc/sysconfig/harddiskhdb, et al. However, this file shouldn't be
needed for basic settings since the kernel does significantly more
autodetection these days. For example, on my UDMA100 system running
2.4.22-1.2087.nptl, with *no* settings in /etc/sysconfig/harddisks:
/dev/hda:
multcount = 16 (on)
IO_support = 1 (32-bit)
unmaskirq = 1 (on)
using_dma = 1 (on)
keepsettings = 0 (off)
readonly = 0 (off)
readahead = 8 (on)
geometry = 4982/255/63, sectors = 80043264, start = 0
Note the equivalent of hdparm's "-m16 -c1 -d1 -u1 -a8" is in play, and I
didn't set a thing. You can verify this both through hdparm (use -i or
-I for more lengthy info) and by checking /proc/ide/[piix|via], for
example. Both my /proc/ide/via and hdparm -i (as well as other tests)
confirm that the drive is running at UDMA-5 (100) speed.
--
Paul W. Frields, RHCE
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