Re: 2.1.111: IDE DMA disabled?

dalecki (
Mon, 27 Jul 1998 13:24:18 -0700 (MST)

On Mon, 27 Jul 1998, Alan Cox wrote:

> > But currently the IDE code is relaying on the fact that the BIOS will do
> > it nicely for Generic DMA, which is basically compleatly wrong. Most of
> > the BIOSes don't get it right. They just put the system in the most secure
> Almost all BIOSes get it right. Furthermore the BIOS knows what the correct
> values are in many cases we cannot even find out or we have to do fairly
> tricky stunts to guess. Judging by the sum collection of reports I have
> we are also talking about almost nobody having actual problems.
> > wired, since I'm using an very old 430HX chipset board with a 300MHz K6,
> > where the BF2 jumper for CPU speed was missing (I have sold it my self to
> > ground level) and the processor isn't detected corretly by the BIOS.
> > Therefore the BIOS can't detect and set the timings correctly.
> "I took a soldering iron to my motherboard, and now..."
> Get real please. For the general case the BIOS is the only thing with a
> good chance of getting the values right
I *have* no actual problems too, even in regard of my wired hardware
messup, but I have observer a significant drop in performance from 10M/s
to about 7M/s after the PIO mode trick got in.

In real life: System Programmer at AIS AXON GmbH

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