Cannot boot from other than Port 1 on Promise TX4 SATA ctrl

[Henrik Olsen]

I have a Promise TX4 SATA controller in my new Gentoo server (with a VIA C3M266 motherboard). It's driving 2 Seagate discs in a software RAID1 (on parts of the discs).

I have a non-RAID /boot on each disc and GRUB installed on both, so I should be able to boot on either disc in case of one of them failing.

But no... When I only connect the second disc (driven on Port 2, and disconnect first disc on Port 1) I cannot boot. The motherboard's BIOS is trying a CDROM-boot since it cannot see any SCSI device (SATA discs are set as SCSI in BIOS and works with Port 1).

When Port/disc 1 is connected all works fine. But it would be very nice if the controller/motherboard bios would let me boot on Port != 1.

Any ideas on solving this?