Setting IDE Bus speed during boot

[bill-CIZd1d4GmLheoWH0uzbU5w at public.gmane.org (bill-CIZd1d4GmLheoWH0uzbU5w at public.gmane.org)]

Thanks for reading this. 

I have a Debian system, and during bootup today, I noticed these 
entries in the syslog (some lines snipped):

kernel: ..... CPU clock speed is 601.0226 MHz.
kernel: ..... host bus clock speed is 66.0802 MHz.

kernel: ide: Assuming 33MHz system bus speed for PIO modes; \
     override with idebus=xx

So, I changed the boot line as follows:

kernel: Kernel command line: root=/dev/hda1 ro idebus=66

But, I got these results:

kernel: ide: Assuming 66MHz system bus speed for PIO modes
kernel: vesafb: probe of vesafb0 failed with error -6
kernel: NET: Registered protocol family 1
kernel: VP_IDE: IDE controller at PCI slot 0000:00:07.1
kernel: VP_IDE: chipset revision 16
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.

Bill Horne