Erros while start roscore in the qemu virtual machine

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Hi, I want to embed the robot operating system on the ARM. So I have done step by step follow the hydro/Installation/OpenEmbedded. I create a Linux Image successfully.Then I run the image in the qemu virtual machine.I execute " $roscore" after set up the environment. But there were the following errors:

File "/usr/lib/python2.7/site-packages/roslaunch/_init_.py",line 243 in main
    uuid=rlutil.get_or_generate_uuid(options.run_id,options.wait_for_master)
File "/usr/lib/python2.7/site-packages/roslaunch/rlutil.py",line 173,in get_or_generate_uuid
     param_server=rosgraph.Master('/roslaunch')
File "/usr/lib/python2.7/site-packages/rosgraph/masterpi.py",line 100,in_init_
     self._reinit(master_uri)
File "/usr/lib/python2.7/site-packages/rosgraph/masterpi.py",line 121,in _reinit
    self.handle=ServerProxy(Self.master_uri)
File "/usr/lib/python2.7/xmlrpclib.py",line 1549,in  _init_
     raise IOError,"unsupported XML-RPC protocol"
IOError:unsupported XML-RPC protocol

please help me .What is the cause of this error? How can I solve it?