Are you sure that libvirt 0.9.3 and before had VirtualBox support
compiled in? If not then VirtualBox can not supersede QEMU in the
autodetection. That might explain it, but I don't see how that can
happen apart from you explicitly disabling VirtualBox support at
configure time.
libvirt 0.9.3:
configure:57866: Drivers
configure:57868:
configure:57870: Xen: no
configure:57872: QEMU: yes
configure:57874: UML: yes
configure:57876: OpenVZ: yes
configure:57878: VMware: yes
configure:57880: VBox: yes
configure:57882: XenAPI: no
configure:57884: xenlight: no
configure:57886: LXC: yes
configure:57888: PHYP: no
configure:57890: ESX: no
configure:57892: Test: yes
configure:57894: Remote: yes
configure:57896: Network: yes
configure:57898: Libvirtd: yes
configure:57900: netcf: no
configure:57902: macvtap: yes
configure:57904: virtport: yes
libvirt 0.9.3 + git (yesterday's)
configure:58371: Drivers
configure:58373:
configure:58375: Xen: no
configure:58377: QEMU: yes
configure:58379: UML: yes
configure:58381: OpenVZ: yes
configure:58383: VMware: yes
configure:58385: VBox: yes
configure:58387: XenAPI: no
configure:58389: xenlight: no
configure:58391: LXC: yes
configure:58393: PHYP: no
configure:58395: ESX: yes
configure:58397: Test: yes
configure:58399: Remote: yes
configure:58401: Network: yes
configure:58403: Libvirtd: yes
configure:58405: netcf: no
configure:58407: macvtap: yes
configure:58409: virtport: yes
(Hmm. Picked up ESX meanwhile.)
Best,
Whit