Comment 23 for bug 595448

yes you need to rebuild the kernel. The problem is the pata_acpi driver that is built in to the kernel. That driver is meant as a driver of last resort. The kernel developers only load it when all other drivers fail to load. BUT, they way the ubuntu kernel devs build the Lucid kernel they changed the ahci driver to be a loadable module. So prior to lucid ahci.ko was present in the kernel image itself and thus would load just fine and the kernel would never even try to load the dreaded papa_acpi driver.

I think they made this change to fix some broken laptops. I search around launchpad and found some folks complain about kernel's prior to lucid because the ahci driver was built in these people could not disable (via blacklisting it). On their systems AHCI caused disk corruption but their BIOS did not allow them to switch back to ATA mode. So I guess the ubuntu devs made this change to accommodate these people and their broken laptops.

Anyway you need to build your own kernel.
https://help.ubuntu.com/community/Kernel/Compile

Just be sure to run:
debian/rules editconfigs
and then (for either x86 or x86-64 edit your config and change ahci to be built in to the kernel instead of as a loaded module)