trace: Provide a generic tracing event descriptor

Uses tracetool to generate a backend-independent tracing event description
(struct TraceEvent).

The values for such structure are generated with the non-public "events"
backend ("events-c" frontend).

The generation of the defines to check if an event is statically enabled is also
moved to the "events" backend ("events-h" frontend).

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

scripts/tracetool/backend/events.py

@@ -0,0 +1,23 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+Generic event description.
+
+This is a dummy backend to establish appropriate frontend/backend compatibility
+checks.
+"""
+
+__author__     = "Lluís Vilanova <vilanova@ac.upc.edu>"
+__copyright__  = "Copyright 2012, 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"
+
+
+def events_h(events):
+    pass
+
+def events_c(events):
+    pass

scripts/tracetool/format/events_c.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+Generate .c for event description.
+"""
+
+__author__     = "Lluís Vilanova <vilanova@ac.upc.edu>"
+__copyright__  = "Copyright 2012, 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"
+
+
+from tracetool import out
+
+
+def begin(events):
+    out('/* This file is autogenerated by tracetool, do not edit. */',
+        '',
+        '#include "trace.h"',
+        '#include "trace/generated-events.h"',
+        '#include "trace/control.h"',
+        '',
+        )
+
+    out('TraceEvent trace_events[TRACE_EVENT_COUNT] = {')
+
+    for e in events:
+        out('    { .id = %(id)s, .name = \"%(name)s\", .sstate = %(sstate)s, .dstate = 0 },',
+            id = "TRACE_" + e.name.upper(),
+            name = e.name,
+            sstate = "TRACE_%s_ENABLED" % e.name.upper(),
+            )
+
+    out('};',
+        '',
+        )

scripts/tracetool/format/events_h.py

@@ -0,0 +1,50 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+Generate .h for event description.
+"""
+
+__author__     = "Lluís Vilanova <vilanova@ac.upc.edu>"
+__copyright__  = "Copyright 2012, 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"
+
+
+from tracetool import out
+
+
+def begin(events):
+    out('/* This file is autogenerated by tracetool, do not edit. */',
+        '',
+        '#ifndef TRACE__GENERATED_EVENTS_H',
+        '#define TRACE__GENERATED_EVENTS_H',
+        '',
+        '#include <stdbool.h>',
+        ''
+        )
+
+    # event identifiers
+    out('typedef enum {')
+
+    for e in events:
+        out('    TRACE_%s,' % e.name.upper())
+
+    out('    TRACE_EVENT_COUNT',
+        '} TraceEventID;',
+        )
+
+    # static state
+    for e in events:
+        if 'disable' in e.properties:
+            enabled = 0
+        else:
+            enabled = 1
+        out('#define TRACE_%s_ENABLED %d' % (e.name.upper(), enabled))
+
+    out('#include "trace/event-internal.h"',
+        '',
+        '#endif  /* TRACE__GENERATED_EVENTS_H */',
+        )

scripts/tracetool/format/h.py

@@ -25,14 +25,7 @@ def begin(events):
         '#include "qemu-common.h"')
 
 def end(events):
-    for e in events:
-        if "disable" in e.properties:
-            enabled = 0
-        else:
-            enabled = 1
-        out('#define TRACE_%s_ENABLED %d' % (e.name.upper(), enabled))
-    out('',
-        '#endif /* TRACE__GENERATED_TRACERS_H */')
+    out('#endif /* TRACE__GENERATED_TRACERS_H */')
 
 def nop(events):
     for e in events: