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Re: getting dma66 support in kernel



On Sun, Aug 20, 2000 at 12:02:33AM -0400, Dave Bresson wrote:

> so i used to be running the 2.2.17-ide kernel which came with potato, but
> have since took it upon myself to go with a homegrown kernel, one which i
> have configured and compiled myself.  I downloaded the source to 2.2.16
> and patched it to the latest 2.2.17pre19.  I configured, and compiled it
> using make-kpkg and installed it.  However, to my dismay, when i compiled
> it i saw no real option for the dma66 support which i need (and yes, i did
> select to show the optional selections in make menuconfig) and so my newly
> compiled kernel does nothing for my dma66 controller on my motherboard.

There is an option called "Use DMA by default if available" in the
Section "General Setup" close to the chipset stuff.

But there may be many reasons why UDMA-66 is not turned on:
1. cables
Do you use proper 66-cables, and did you make sure they are not too
long?
2. some other device on the same controller interferes with the HD
3. HD and controller are not 100% compatible

I would recommend to do the following:
Try to turn on UDMA by using the programm "hdparm"

hdparm -d1 /dev/hd?

If you can turn in on this way you can set the mode by using these
options:
-X66 for UDMA-33 (!)
-X68 for UDMA-66

If it is possible to switch to UDMA-66 this way but the HD won't do it
by itself you can put this line in /etc/init.d/bootmisc.sh

hdparm -d1 -X68 /dev/hd?

HTH
Phil



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