Boot loader didn't return any data!

启动虚机报错：

Error: Boot loader didn't return any data!
Usage: xm start <DomainName>

Start a Xend managed domain
  -p, --paused                   Do not unpause domain after starting it   
  -c, --console_autoconnect      Connect to the console after the domain   
                                 is created
  --vncviewer                    Connect to display via VNC after the      
                                 domain is created
  --vncviewer-autopass           Pass VNC password to viewer via stdin and 
                                 -autopass

原因：

1. 在使用PyGrub 时需注意硬碟指定的顺序. disk = [ "phy:/dev/sda5,xvda,w", "phy:/dev/sda6,xvdb,w" ] 包含/boot 的partition 必须指定为第一颗.不然系统会无法载入bootloader 并且回报出。
2. 虚机文件系统严重损坏。