ahci should attach to Intel ICH8 'RAID controller'
The Intel ICH8 chipset has a controller that is a combo 'RAID/AHCI' controller. It actually is an ahci controller, but self-identifies using the RAID controller pci class, which is why ahci doesn't attach to it. If you manually attach ahci to it, it works just fine. From looking at other systems, they also attach ahci to it. From the user who has the device, it appears that attaching it to ahci is working fine, which is what we'd expect. We should add the PCI device for this specific device to the ahci manifest.
Updated by Jean-Pierre André about 6 years ago
I can confirm that the controller below can be used in AHCI mode, provided the RAID mode is disabled in the BIOS :
pci bus 0x0000 cardnum 0x1f function 0x02: vendor 0x8086 device 0x282a
Intel Corporation 82801 Mobile SATA Controller [RAID mode]
CardVendor 0x103c card 0x1894 (Hewlett-Packard Company, Card unknown)
This one also... but I could not find how to disable the RAID mode (other than by removing a disk)... and ZFS hates having competitors in the RAID business, so it is de facto unusable with Illumos.
pci bus 0x0000 cardnum 0x1f function 0x02: vendor 0x8086 device 0x2822
Intel Corporation 82801 SATA Controller [RAID mode]
CardVendor 0x1028 card 0x0214 (Dell, Card unknown)