Re: Bus-Mastered DMA support for Triton Chipset?

mlord (
Tue, 30 Sep 1997 16:13:03 -0400

Richard S. Gray wrote:
> going on. I first compile support into my kernel by selecting:
> [*] Intel PIIX/PIIX3/PIIX4 (Triton 430FX/HX/VX/TX, 440FX) DMA support
> I then added the following code to my rc.local initialization script:
> echo "Setting hda transfer mode to DMA mode2"
> /sbin/hdparm -d1 -X34 /dev/hda
> echo "Setting hdb transfer mode to DMA mode2"
> /sbin/hdparm -d1 -X34 /dev/hdb
> However, when cat /proc/dma I get:
> 1: SoundBlaster8
> 4: cascade
> 5: SoundBlaster16
> I believe the DMA BusMastering is probably working but I would like to
> understand a little more about
> what is going on. Shouldn't a channel be allocated for the ide drive?
> Or does this form of DMA bypass
> the DMA controller found on the main board. If yes then does this mean
> that the DMA controller is
> actually on the drive itself?

The PIIX chip (part of the "triton" chipsets) includes a dedicated DMA
controller for each IDE interface. That's why no allocation is required
as would be shown in /proc/dma.