[vdr] Re: No DMA used

["Sven Karlsson" <svenka@it.kth.se>]

Hi,

> switched on (hdparm) and while booting it's seems to be enabled
> correctly. But the max. datarate is to low and it takes about 95% of

Exactly how do you see that DMA is switched on? You must have UDMA support
for your specific controller built into the kernel as to be able to use it.

> I'm using Kernel 2.4.4-4GB (Suse 7.2) and it's an IBM Board with a

Also remember that not all chipsets support DMA at all. The early pentium
chipsets had very little support for good DMA modes. Most early chipsets
only support busmaster DMA which isn't very fast. Often even PIO modes are
faster than busmaster DMA.

My experience is that intel chipsets are the most capable/supported when it
comes to UDMA. I'm having serious troubles with my 160GB maxtor on an ALi
chipset (all DMA modes, even busmaster DMA, just hangs the machine) while
the same type of drive runs fine on an old intel chipset (in all supported
DMA modes).

I've very little experice with Via chipsets and large drives. I have a few
Via motherboards but I am only running smaller 40GB drives on those.

Best regards
 Sven