前面讲到了PV guest的配置，那么这篇再简单说一下Xen中HVM guest的配置吧。以下配置适用于Xen4.1及以上版本，xlexample.hvm如下：
# =====================================================================
# Example HVM guest configuration
# =====================================================================
#
# This is a fairly minimal example of what is required for an
# HVM guest. For a more complete guide see xl.cfg(5)
# This configures an HVM rather than PV guest
builder = "hvm"
# Guest name
name = "Jay's HVM"
# Initial memory allocation (MB)
memory = 1024
# Maximum memory (MB)
# If this is greater than `memory' then the slack will start ballooned
# (this assumes guest kernel support for ballooning)
#maxmem = 512
# Number of VCPUS
vcpus = 2
# Network devices
# A list of 'vifspec' entries as described in
# docs/misc/xl-network-configuration.markdown
vif = [ '' ]
# Disk Devices
# A list of `diskspec' entries as described in
# docs/misc/xl-disk-configuration.txt
disk = [ '/root/jay/rhel6u2.qcow,qcow2,xvda,rw' ]
其中值得注意是网络配置vif=[”]，它其实都主要用了xl的默认配置，相当如下：
vif = [ ‘type=ioemu, bridge=xenbr0’ ]
type指明了guest中网卡设备的类型；有两个值：ioemu 和 vif。 其中ioemu表示使用qemu模拟的网络设备，而当Guest中有支持网络设备的PV driver时,‘ioemu’的配置依然会让hvm guest使用PV driver；而vif则只提供PV driver的方式让hvm guest使用。
Specifies the type of device to valid values are:
ioemu (default) — this device will be provided as an emulate device to the guest and also as a paravirtualised device which the guest may choose to use instead if it has suitable drivers available.
vif — this device will be provided as a paravirtualised device only.
用xl create xlexample.hvm 来创建一个hvm guest。