[libvirt] AHCI support in qemu driver

I have some time this week to work on libvirt and thought Daniel's suggestion [1] for adding AHCI support in the qemu driver would be a useful endeavor. I've managed to start a qemu instance using AHCI with attached hackery, iff I have a controller defined. E.g. <disk type='file' device='disk'> <driver name='qemu' type='raw'/> <source file='/var/lib/libvirt/images/test/disk0.raw'/> <target dev='sda' bus='sata'/> </disk> <controller type='sata' index='0'> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </controller> which results in qemu args -device ahci,id=ahci0,bus=pci.0,multifunction=on,addr=0x3.0x0 -drive file=/var/lib/libvirt/images/test/disk0.raw,if=none,id=drive-sata-dik0,format=raw -device ide-drive,bus=ahci0.0,drive=drive-sata-disk0,id=sata-disk0,bootindex=1 If the controller is not explicitly defined, the AHCI device (-device ahci,...) is not created and qemu fails with qemu-kvm: -device ide-drive,bus=ahci0.0,drive=drive-sata-disk0,id=sata-disk0,bootindex=1: Bus 'a hci0.0' not found I'm not quite sure how to create the controller when not explicitly defined in the config. Also, I suspect there are many things I'm missing in adding support for this controller. E.g., I've ignored hotplug for the moment. What would be considered minimal functionality for supporting this controller? Thanks! Jim [1] http://www.redhat.com/archives/libvir-list/2011-August/msg01034.html