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diff --git a/qemu/scripts/tracetool/backend/__init__.py b/qemu/scripts/tracetool/backend/__init__.py
new file mode 100644
index 000000000..d4b6dab9c
--- /dev/null
+++ b/qemu/scripts/tracetool/backend/__init__.py
@@ -0,0 +1,123 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+Backend management.
+
+
+Creating new backends
+---------------------
+
+A new backend named 'foo-bar' corresponds to Python module
+'tracetool/backend/foo_bar.py'.
+
+A backend module should provide a docstring, whose first non-empty line will be
+considered its short description.
+
+All backends must generate their contents through the 'tracetool.out' routine.
+
+
+Backend attributes
+------------------
+
+========= ====================================================================
+Attribute Description
+========= ====================================================================
+PUBLIC    If exists and is set to 'True', the backend is considered "public".
+========= ====================================================================
+
+
+Backend functions
+-----------------
+
+All the following functions are optional, and no output will be generated if
+they do not exist.
+
+=============================== ==============================================
+Function                        Description
+=============================== ==============================================
+generate_<format>_begin(events) Generate backend- and format-specific file
+                                header contents.
+generate_<format>_end(events)   Generate backend- and format-specific file
+                                footer contents.
+generate_<format>(event)        Generate backend- and format-specific contents
+                                for the given event.
+=============================== ==============================================
+
+"""
+
+__author__     = "Lluís Vilanova <vilanova@ac.upc.edu>"
+__copyright__  = "Copyright 2012-2014, Lluís Vilanova <vilanova@ac.upc.edu>"
+__license__    = "GPL version 2 or (at your option) any later version"
+
+__maintainer__ = "Stefan Hajnoczi"
+__email__      = "stefanha@linux.vnet.ibm.com"
+
+
+import os
+
+import tracetool
+
+
+def get_list(only_public = False):
+    """Get a list of (name, description) pairs."""
+    res = [("nop", "Tracing disabled.")]
+    modnames = []
+    for filename in os.listdir(tracetool.backend.__path__[0]):
+        if filename.endswith('.py') and filename != '__init__.py':
+            modnames.append(filename.rsplit('.', 1)[0])
+    for modname in sorted(modnames):
+        module = tracetool.try_import("tracetool.backend." + modname)
+
+        # just in case; should never fail unless non-module files are put there
+        if not module[0]:
+            continue
+        module = module[1]
+
+        public = getattr(module, "PUBLIC", False)
+        if only_public and not public:
+            continue
+
+        doc = module.__doc__
+        if doc is None:
+            doc = ""
+        doc = doc.strip().split("\n")[0]
+
+        name = modname.replace("_", "-")
+        res.append((name, doc))
+    return res
+
+
+def exists(name):
+    """Return whether the given backend exists."""
+    if len(name) == 0:
+        return False
+    if name == "nop":
+        return True
+    name = name.replace("-", "_")
+    return tracetool.try_import("tracetool.backend." + name)[1]
+
+
+class Wrapper:
+    def __init__(self, backends, format):
+        self._backends = [backend.replace("-", "_") for backend in backends]
+        self._format = format.replace("-", "_")
+        for backend in self._backends:
+            assert exists(backend)
+        assert tracetool.format.exists(self._format)
+
+    def _run_function(self, name, *args, **kwargs):
+        for backend in self._backends:
+            func = tracetool.try_import("tracetool.backend." + backend,
+                                        name % self._format, None)[1]
+            if func is not None:
+                func(*args, **kwargs)
+
+    def generate_begin(self, events):
+        self._run_function("generate_%s_begin", events)
+
+    def generate(self, event):
+        self._run_function("generate_%s", event)
+
+    def generate_end(self, events):
+        self._run_function("generate_%s_end", events)