Erik Slagter wrote:

I guess the only way to have, for example the ICH6, not using legacy
IRQ/ports, is to switch it to AHCI, which only the BIOS can do (if
implemented).

"native mode" is where PATA and/or SATA PCI device is programmed into 
full PCI mode -- PCI BARs, PCI irq, etc.  Some BIOSen allow you to 
enable mode, which disables all use of legacy IRQ/ports.

Also, ICH6 silicon does not support AHCI, only ICH6-R and ICH6-M.

	Jeff