Re: 2.1.111: IDE DMA disabled...BLAH...BLAH...

Mark Lord (
Tue, 28 Jul 1998 19:36:19 -0400

Andre M. Hedrick wrote:
> Greetings All from the other Andre,
> There is Andrew Derrick Balsa aka "Andre" and me "Andre".
> As for the (U)DMA question, would it not be sensible for us to flag
> the drive capablities.

No, it would not be.

We cannot blindly (and dangerously) reprogram the DMA mode
of the drive without knowing what mode the IDE interface
chipset is trying to use. The two must match.

If the chipset is BIOS-configured for UDMA,
then we could break things big-time by selecting DMA at the drive..

Bad Idea.

The IDE driver already does the Most Sensible things by default,
leaving the chipset and drive settings as set-up by the BIOS.

If DMA fails, the IDE driver automatically falls back to PIO mode,
without loss of data or corruption of any sort.

There are NO current documented cases of disk corruption due to DMA
in the Linux IDE driver. If anyone thinks they know of such a case,
I'd be happy to investigate it .. but all such cases thus far have
been proven bogus.

I will not be updating the IDE driver again
until the linux/drivers/block/ file
is restored to its pre-111 state.

The Linux IDE guy

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