Revert 17499:451ae3b8e5c8

Breaks HVM guest creation (bugzilla #1221).

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>

tools/python/xen/xend/XendDomainInfo.py

@@ -1837,9 +1837,6 @@ class XendDomainInfo:
 
         @raise: VmError for invalid devices
         """
-        if self.image:
-            self.image.prepareEnvironment()
-
         ordered_refs = self.info.ordered_device_refs()
         for dev_uuid in ordered_refs:
             devclass, config = self.info['devices'][dev_uuid]

tools/python/xen/xend/image.py

@@ -185,30 +185,6 @@ class ImageHandler:
         """Build the domain. Define in subclass."""
         raise NotImplementedError()
 
-    def prepareEnvironment(self):
-        """Prepare the environment for the execution of the domain. This
-        method is called before any devices are set up."""
-        
-        domid = self.vm.getDomid()
-	
-        # Delete left-over pipes
-        try:
-            os.unlink('/var/run/tap/qemu-read-%d' % domid)
-            os.unlink('/var/run/tap/qemu-write-%d' % domid)
-        except:
-            pass
-
-        # No device model, don't create pipes
-        if self.device_model is None:
-            return
-
-        # If we use a device model, the pipes for communication between
-        # blktapctrl and ioemu must be present before the devices are 
-        # created (blktapctrl must access them for new block devices)
-        os.mkfifo('/var/run/tap/qemu-read-%d' % domid, 0600)
-        os.mkfifo('/var/run/tap/qemu-write-%d' % domid, 0600)
-        
-
     # Return a list of cmd line args to the device models based on the
     # xm config file
     def parseDeviceModelArgs(self, vmConfig):
@@ -435,12 +411,6 @@ class ImageHandler:
             self.pid = None
             state = xstransact.Remove("/local/domain/0/device-model/%i"
                                       % self.vm.getDomid())
-            
-            try:
-                os.unlink('/var/run/tap/qemu-read-%d' % self.vm.getDomid())
-                os.unlink('/var/run/tap/qemu-write-%d' % self.vm.getDomid())
-            except:
-                pass
 
 
 class LinuxImageHandler(ImageHandler):