Re: UDMA66 without proper cable?

From: Jan Niehusmann (
Date: Wed May 24 2000 - 14:49:53 EST

On Wed, May 24, 2000 at 12:33:37PM -0700, Dr. Kelsey Hudson wrote:
> You didn't read that error message well enough. :)
> Look, you can pass a kernel parameter on boot with the
> idebus=33
> option to tell it to go to UDMA/33 instead of UDMA/66.

You didn't read that error message well enough. :)
(in fact, maybe it's not your fault, but the massage is a little bit

idebus doesn't set UDMA speed, it sets the system bus speed that is
used in ide timing calculations. From ide.c:

 * ide_system_bus_speed() returns what we think is the system VESA/PCI
 * bus speed (in MHz). This is used for calculating interface PIO timings.
 * The default is 40 for known PCI systems, 50 otherwise.
 * The "idebus=xx" parameter can be used to override this value.
 * The actual value to be used is computed/displayed the first time through.


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