> On Thu, 27 Nov 1997, mlord wrote:
>
> > Alan Cox wrote:
> > >
> > > a) Some BIOSes turn DMA on when they shouldnt
> >
> > Rare, and Linux makes its own decision anyway.
> >
>
> My TX97-E bios starts up my QUANTUM FIREBALL ST2.1A as UDMA 2, but linux
> 2.1.66 sets DMA off. I have to turn it on with hdparm. I am not clear why
> linux does this. How does linux make its decision?
>
> OTOH linux and the bios both start my ST51270A on pio 4, which seems
> clearly correct as turning on DMA gives occasional timing errors.
You explained why yourself.. :) Some drives trash data with dma on.. So
linux doesn't turn it on, you have to make a decision to foul up you
data.. Just stick hdparm in your startup scripts if you know it works with
that drive..