nova如何修改libvirt.xml及自定义xml文件修改nova代码支持vhost

def get_config(self, instance, vif, image_meta, inst_type):

conf = vconfig.LibvirtConfigGuestInterface()

# Default to letting libvirt / the hypervisor choose the model

model = None

driver = None

# If the user has specified a 'vif_model' against the

# image then honour that model

if image_meta:

vif_model = image_meta.get('properties',

{}).get('hw_vif_model')

if vif_model is not None:

model = vif_model

# Else if the virt type is KVM/QEMU, use virtio according

# to the global config parameter

if (model is None and

CONF.libvirt.virt_type in ('kvm', 'qemu') and

CONF.libvirt.use_virtio_for_bridges):

model = "virtio"

# Workaround libvirt bug, where it mistakenly

# enables vhost mode, even for non-KVM guests

if model == "virtio" and CONF.libvirt.virt_type == "qemu":

driver = "qemu"

if model == "virtio" and CONF.libvirt.virt_type == "qemu":

driver = "qemu"

driver = "qemu"//增加此句，代表永远为qemu