qemu-xen (git://xenbits.xen.org/qemu-xen.git) is only supported for
security fixes when used together with the Xen hypervisor and only with
a subset of all the possible QEMU emulators. Specifically:

- network: e1000, rtl8139, virtio-net
- storage: piix3 ide, ahci, xen_disk
- backing storage image format: raw, qcow, qcow2, vhd
- graphics: cirris-vga, stdvga and xenfb
- audio: sb16, es1370, ac97
- input: Xen PV keyboard and mouse (part of xenfb), USB and PS/2
         keyboard and mouse
- serial cards: UART 16550A

Core components, such as the PCI host bridge and the PIIX3 chipset, are
supported. All devices of one the above classes, which are not explicitly
mentioned, are not supported. For example the ne2000 network card is not
supported. 

If you think that a specific emulated device should be supported, please
contact the QEMU UPSTREAM maintainer and the Xen Security Team
(security@xenproject.org).