首先安装好系统centos系统，宿主机只安装base的基本包，然后用yum安装常见的xen,kernel-xen软件。
2.xen软件安装好之后检查一下/etc/grub.conf文件设置启动选项为后缀为xen 的内核，最后reboot重新启动。
3.系统启动好之后查看宿主机信息
[root@localhost ~]# xm li //xm list显示domain 0的信息。
Name ID Mem(MiB) VCPUs State Time(s)
Domain-0 0 282 1 r----- 804.7
4.ifconfig -a查看桥和虚拟网卡
xen的网络桥接模式的工作流程，现翻译在下面以备后面之需。
When xend is started, with the default configuration (in /etc/xen/xend-config.sxp), it'll execute /etc/xen/scripts/network-bridge to re-configure your networking.
当xend这个进程被开启之后，进程会根据默认的配置文件/etc/xen/xend-config.sxp里的内容，让/etc/xen/scripts/network-bridge这个脚本发挥工作，重新来配置你的网络。
It'll rename the physical eth0 interface to peth0, change it's MAC address to FE:FF:FF:FF:FF:FF, and then create a virtual ethernet interface called eth0, configure it with the real MAC address, and bridge both of those interfaces to xenbr0 bridge.
它会将你的eth0重命名为peth0，把eth0的MAC值改为FE:FF:FF:FF:FF:FF。然后再重新创建一个虚拟的网络接口，将它命名为eth0，配置它让它有物理上的MAC地址，然后把peth0跟eth0这两个接口跟xenbr0做一个桥接。
This way the virtual eth0 interface should have a real MAC, and it can be used for dom0 management, and at the same time allow other VMs/domUs to share the physical ethernet interface by using xenbr0 bridge.