Setting IDE Bus speed during boot

[richard.pieri-Re5JQEeQqe8AvxtiuMwx3w at public.gmane.org (Richard Pieri)]

On Jan 13, 2010, at 12:12 PM, bill-CIZd1d4GmLheoWH0uzbU5w at public.gmane.org wrote:
> 
> kernel: VP_IDE: not 100%% native mode: will probe irqs later
> kernel: VP_IDE: User given PCI clock speed impossible (66000), using 33 MHz instead.
> 
> ... and I'd like all devices to use the bus at 66MHz, so please tell me how. Thank you.

You actually don't want everything at 66MHz PIO.  More specifically, you don't want your disks to use PIO at all if they support DMA which they almost certainly do on a PCI bus.  What you should do is let the system boot normally, get that idebus=xx bit out of there.  Let it boot.  Then fire up a root shell and use hdparm to query your drives and make sure that they are individually using the correct DMA modes.

--Rich P.