trace: [tracetool] Minimize the amount of per-backend code

Backends now only contain the essential backend-specific code, and most of the work is moved to frontend code.

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

scripts/tracetool/format/d.py

@@ -16,5 +16,27 @@ __email__      = "stefanha@linux.vnet.ibm.com"
 from tracetool import out
 
 
-def begin(events):
-    out('/* This file is autogenerated by tracetool, do not edit. */')
+def generate(events, backend):
+    events = [e for e in events
+              if "disable" not in e.properties]
+
+    out('/* This file is autogenerated by tracetool, do not edit. */'
+        '',
+        'provider qemu {')
+
+    for e in events:
+        args = str(e.args)
+
+        # DTrace provider syntax expects foo() for empty
+        # params, not foo(void)
+        if args == 'void':
+            args = ''
+
+        # Define prototype for probe arguments
+        out('',
+            'probe %(name)s(%(args)s);',
+            name=e.name,
+            args=args)
+
+    out('',
+        '};')