Patchwork [v8,1/8] tracetool: Rewrite infrastructure as python modules

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Submitter Lluís Vilanova
Date April 3, 2012, 6:47 p.m.
Message ID <20120403184738.2908.82990.stgit@ginnungagap.bsc.es>
Download mbox | patch
Permalink /patch/150523/
State New
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Lluís Vilanova - April 3, 2012, 6:47 p.m.
Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
---
 Makefile.objs                         |    6 
 Makefile.target                       |   13 -
 configure                             |    4 
 scripts/tracetool                     |  648 ---------------------------------
 scripts/tracetool.py                  |  108 ++++++
 scripts/tracetool/__init__.py         |  262 +++++++++++++
 scripts/tracetool/backend/__init__.py |  111 ++++++
 scripts/tracetool/format/__init__.py  |   99 +++++
 8 files changed, 592 insertions(+), 659 deletions(-)
 delete mode 100755 scripts/tracetool
 create mode 100755 scripts/tracetool.py
 create mode 100644 scripts/tracetool/__init__.py
 create mode 100644 scripts/tracetool/backend/__init__.py
 create mode 100644 scripts/tracetool/format/__init__.py

Patch

diff --git a/Makefile.objs b/Makefile.objs
index 5f0b3f7..228a756 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -357,12 +357,12 @@  else
 trace.h: trace.h-timestamp
 endif
 trace.h-timestamp: $(SRC_PATH)/trace-events $(BUILD_DIR)/config-host.mak
-	$(call quiet-command,sh $(SRC_PATH)/scripts/tracetool --$(TRACE_BACKEND) -h < $< > $@,"  GEN   trace.h")
+	$(call quiet-command,$(PYTHON) $(SRC_PATH)/scripts/tracetool.py --format=h --backend=$(TRACE_BACKEND) < $< > $@,"  GEN   trace.h")
 	@cmp -s $@ trace.h || cp $@ trace.h
 
 trace.c: trace.c-timestamp
 trace.c-timestamp: $(SRC_PATH)/trace-events $(BUILD_DIR)/config-host.mak
-	$(call quiet-command,sh $(SRC_PATH)/scripts/tracetool --$(TRACE_BACKEND) -c < $< > $@,"  GEN   trace.c")
+	$(call quiet-command,$(PYTHON) $(SRC_PATH)/scripts/tracetool.py --format=c --backend=$(TRACE_BACKEND) < $< > $@,"  GEN   trace.c")
 	@cmp -s $@ trace.c || cp $@ trace.c
 
 trace.o: trace.c $(GENERATED_HEADERS)
@@ -375,7 +375,7 @@  trace-dtrace.h: trace-dtrace.dtrace
 # rule file. So we use '.dtrace' instead
 trace-dtrace.dtrace: trace-dtrace.dtrace-timestamp
 trace-dtrace.dtrace-timestamp: $(SRC_PATH)/trace-events $(BUILD_DIR)/config-host.mak
-	$(call quiet-command,sh $(SRC_PATH)/scripts/tracetool --$(TRACE_BACKEND) -d < $< > $@,"  GEN   trace-dtrace.dtrace")
+	$(call quiet-command,$(PYTHON) $(SRC_PATH)/scripts/tracetool.py --format=d --backend=$(TRACE_BACKEND) < $< > $@,"  GEN   trace-dtrace.dtrace")
 	@cmp -s $@ trace-dtrace.dtrace || cp $@ trace-dtrace.dtrace
 
 trace-dtrace.o: trace-dtrace.dtrace $(GENERATED_HEADERS)
diff --git a/Makefile.target b/Makefile.target
index 1bd25a8..c1e58fb 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -59,12 +59,13 @@  TARGET_TYPE=system
 endif
 
 $(QEMU_PROG).stp:
-	$(call quiet-command,sh $(SRC_PATH)/scripts/tracetool \
-		--$(TRACE_BACKEND) \
-		--binary $(bindir)/$(QEMU_PROG) \
-		--target-arch $(TARGET_ARCH) \
-		--target-type $(TARGET_TYPE) \
-		--stap < $(SRC_PATH)/trace-events > $(QEMU_PROG).stp,"  GEN   $(QEMU_PROG).stp")
+	$(call quiet-command,$(PYTHON) $(SRC_PATH)/scripts/tracetool.py \
+		--format=stap \
+		--backend=$(TRACE_BACKEND) \
+		--binary=$(bindir)/$(QEMU_PROG) \
+		--target-arch=$(TARGET_ARCH) \
+		--target-type=$(TARGET_TYPE) \
+		< $(SRC_PATH)/trace-events > $(QEMU_PROG).stp,"  GEN   $(QEMU_PROG).stp")
 else
 stap:
 endif
diff --git a/configure b/configure
index d7631ed..bea4a2c 100755
--- a/configure
+++ b/configure
@@ -1097,7 +1097,7 @@  echo "  --disable-docs           disable documentation build"
 echo "  --disable-vhost-net      disable vhost-net acceleration support"
 echo "  --enable-vhost-net       enable vhost-net acceleration support"
 echo "  --enable-trace-backend=B Set trace backend"
-echo "                           Available backends:" $("$source_path"/scripts/tracetool --list-backends)
+echo "                           Available backends:" $($python "$source_path"/scripts/tracetool.py --list-backends)
 echo "  --with-trace-file=NAME   Full PATH,NAME of file to store traces"
 echo "                           Default:trace-<pid>"
 echo "  --disable-spice          disable spice"
@@ -2654,7 +2654,7 @@  fi
 ##########################################
 # check if trace backend exists
 
-sh "$source_path/scripts/tracetool" "--$trace_backend" --check-backend > /dev/null 2> /dev/null
+$python "$source_path/scripts/tracetool.py" "--backend=$trace_backend" --check-backend  > /dev/null 2> /dev/null
 if test "$?" -ne 0 ; then
   echo
   echo "Error: invalid trace backend"
diff --git a/scripts/tracetool b/scripts/tracetool
deleted file mode 100755
index 65bd0a1..0000000
--- a/scripts/tracetool
+++ /dev/null
@@ -1,648 +0,0 @@ 
-#!/bin/sh
-#
-# Code generator for trace events
-#
-# Copyright IBM, Corp. 2010
-#
-# This work is licensed under the terms of the GNU GPL, version 2.  See
-# the COPYING file in the top-level directory.
-
-# Disable pathname expansion, makes processing text with '*' characters simpler
-set -f
-
-usage()
-{
-    cat >&2 <<EOF
-usage: $0 [--nop | --simple | --stderr | --ust | --dtrace] [-h | -c]
-Generate tracing code for a file on stdin.
-
-Backends:
-  --nop     Tracing disabled
-  --simple  Simple built-in backend
-  --stderr  Stderr built-in backend
-  --ust     LTTng User Space Tracing backend
-  --dtrace  DTrace/SystemTAP backend
-
-Output formats:
-  -h     Generate .h file
-  -c     Generate .c file
-  -d     Generate .d file (DTrace only)
-  --stap Generate .stp file (DTrace with SystemTAP only)
-
-Options:
-  --binary       [path]    Full path to QEMU binary
-  --target-arch  [arch]    QEMU emulator target arch
-  --target-type  [type]    QEMU emulator target type ('system' or 'user')
-  --probe-prefix [prefix]  Prefix for dtrace probe names
-                           (default: qemu-\$targettype-\$targetarch)
-
-EOF
-    exit 1
-}
-
-# Print a line without interpreting backslash escapes
-#
-# The built-in echo command may interpret backslash escapes without an option
-# to disable this behavior.
-puts()
-{
-    printf "%s\n" "$1"
-}
-
-# Get the name of a trace event
-get_name()
-{
-    local name
-    name=${1%%\(*}
-    echo "${name##* }"
-}
-
-# Get the given property of a trace event
-# 1: trace-events line
-# 2: property name
-# -> return 0 if property is present, or 1 otherwise
-has_property()
-{
-    local props prop
-    props=${1%%\(*}
-    props=${props% *}
-    for prop in $props; do
-        if [ "$prop" = "$2" ]; then
-            return 0
-        fi
-    done
-    return 1
-}
-
-# Get the argument list of a trace event, including types and names
-get_args()
-{
-    local args
-    args=${1#*\(}
-    args=${args%%\)*}
-    echo "$args"
-}
-
-# Get the argument name list of a trace event
-get_argnames()
-{
-    local nfields field name sep
-    nfields=0
-    sep="$2"
-    for field in $(get_args "$1"); do
-        nfields=$((nfields + 1))
-
-        # Drop pointer star
-        field=${field#\*}
-
-        # Only argument names have commas at the end
-        name=${field%,}
-        test "$field" = "$name" && continue
-
-        printf "%s%s " $name $sep
-    done
-
-    # Last argument name
-    if [ "$nfields" -gt 1 ]
-    then
-        printf "%s" "$name"
-    fi
-}
-
-# Get the number of arguments to a trace event
-get_argc()
-{
-    local name argc
-    argc=0
-    for name in $(get_argnames "$1", ","); do
-        argc=$((argc + 1))
-    done
-    echo $argc
-}
-
-# Get the format string including double quotes for a trace event
-get_fmt()
-{
-    puts "${1#*)}"
-}
-
-linetoh_begin_nop()
-{
-    return
-}
-
-linetoh_nop()
-{
-    local name args
-    name=$(get_name "$1")
-    args=$(get_args "$1")
-
-    # Define an empty function for the trace event
-    cat <<EOF
-static inline void trace_$name($args)
-{
-}
-EOF
-}
-
-linetoh_end_nop()
-{
-    return
-}
-
-linetoc_begin_nop()
-{
-    return
-}
-
-linetoc_nop()
-{
-    # No need for function definitions in nop backend
-    return
-}
-
-linetoc_end_nop()
-{
-    return
-}
-
-linetoh_begin_simple()
-{
-    cat <<EOF
-#include "trace/simple.h"
-EOF
-
-    simple_event_num=0
-}
-
-cast_args_to_uint64_t()
-{
-    local arg
-    for arg in $(get_argnames "$1", ","); do
-        printf "%s" "(uint64_t)(uintptr_t)$arg"
-    done
-}
-
-linetoh_simple()
-{
-    local name args argc trace_args
-    name=$(get_name "$1")
-    args=$(get_args "$1")
-    argc=$(get_argc "$1")
-
-    trace_args="$simple_event_num"
-    if [ "$argc" -gt 0 ]
-    then
-        trace_args="$trace_args, $(cast_args_to_uint64_t "$1")"
-    fi
-
-    cat <<EOF
-static inline void trace_$name($args)
-{
-    trace$argc($trace_args);
-}
-EOF
-
-    simple_event_num=$((simple_event_num + 1))
-}
-
-linetoh_end_simple()
-{
-    cat <<EOF
-#define NR_TRACE_EVENTS $simple_event_num
-extern TraceEvent trace_list[NR_TRACE_EVENTS];
-EOF
-}
-
-linetoc_begin_simple()
-{
-    cat <<EOF
-#include "trace.h"
-
-TraceEvent trace_list[] = {
-EOF
-    simple_event_num=0
-
-}
-
-linetoc_simple()
-{
-    local name
-    name=$(get_name "$1")
-    cat <<EOF
-{.tp_name = "$name", .state=0},
-EOF
-    simple_event_num=$((simple_event_num + 1))
-}
-
-linetoc_end_simple()
-{
-    cat <<EOF
-};
-EOF
-}
-
-#STDERR
-linetoh_begin_stderr()
-{
-    cat <<EOF
-#include <stdio.h>
-#include "trace/stderr.h"
-
-extern TraceEvent trace_list[];
-EOF
-
-    stderr_event_num=0
-}
-
-linetoh_stderr()
-{
-    local name args argnames argc fmt
-    name=$(get_name "$1")
-    args=$(get_args "$1")
-    argnames=$(get_argnames "$1" ",")
-    argc=$(get_argc "$1")
-    fmt=$(get_fmt "$1")
-
-    if [ "$argc" -gt 0 ]; then
-        argnames=", $argnames"
-    fi
-
-    cat <<EOF
-static inline void trace_$name($args)
-{
-    if (trace_list[$stderr_event_num].state != 0) {
-        fprintf(stderr, "$name " $fmt "\n" $argnames);
-    }
-}
-EOF
-    stderr_event_num=$((stderr_event_num + 1))
-
-}
-
-linetoh_end_stderr()
-{
-    cat <<EOF
-#define NR_TRACE_EVENTS $stderr_event_num
-EOF
-}
-
-linetoc_begin_stderr()
-{
-    cat <<EOF
-#include "trace.h"
-
-TraceEvent trace_list[] = {
-EOF
-    stderr_event_num=0
-}
-
-linetoc_stderr()
-{
-    local name
-    name=$(get_name "$1")
-    cat <<EOF
-{.tp_name = "$name", .state=0},
-EOF
-    stderr_event_num=$(($stderr_event_num + 1))
-}
-
-linetoc_end_stderr()
-{
-    cat <<EOF
-};
-EOF
-}
-#END OF STDERR
-
-# Clean up after UST headers which pollute the namespace
-ust_clean_namespace() {
-    cat <<EOF
-#undef mutex_lock
-#undef mutex_unlock
-#undef inline
-#undef wmb
-EOF
-}
-
-linetoh_begin_ust()
-{
-    echo "#include <ust/tracepoint.h>"
-    ust_clean_namespace
-}
-
-linetoh_ust()
-{
-    local name args argnames
-    name=$(get_name "$1")
-    args=$(get_args "$1")
-    argnames=$(get_argnames "$1", ",")
-
-    cat <<EOF
-DECLARE_TRACE(ust_$name, TP_PROTO($args), TP_ARGS($argnames));
-#define trace_$name trace_ust_$name
-EOF
-}
-
-linetoh_end_ust()
-{
-    return
-}
-
-linetoc_begin_ust()
-{
-    cat <<EOF
-#include <ust/marker.h>
-$(ust_clean_namespace)
-#include "trace.h"
-EOF
-}
-
-linetoc_ust()
-{
-    local name args argnames fmt
-    name=$(get_name "$1")
-    args=$(get_args "$1")
-    argnames=$(get_argnames "$1", ",")
-    [ -z "$argnames" ] || argnames=", $argnames"
-    fmt=$(get_fmt "$1")
-
-    cat <<EOF
-DEFINE_TRACE(ust_$name);
-
-static void ust_${name}_probe($args)
-{
-    trace_mark(ust, $name, $fmt$argnames);
-}
-EOF
-
-    # Collect names for later
-    names="$names $name"
-}
-
-linetoc_end_ust()
-{
-    cat <<EOF
-static void __attribute__((constructor)) trace_init(void)
-{
-EOF
-
-    for name in $names; do
-        cat <<EOF
-    register_trace_ust_$name(ust_${name}_probe);
-EOF
-    done
-
-    echo "}"
-}
-
-linetoh_begin_dtrace()
-{
-    cat <<EOF
-#include "trace-dtrace.h"
-EOF
-}
-
-linetoh_dtrace()
-{
-    local name args argnames nameupper
-    name=$(get_name "$1")
-    args=$(get_args "$1")
-    argnames=$(get_argnames "$1", ",")
-
-    nameupper=`echo $name | tr '[:lower:]' '[:upper:]'`
-
-    # Define an empty function for the trace event
-    cat <<EOF
-static inline void trace_$name($args) {
-    QEMU_${nameupper}($argnames);
-}
-EOF
-}
-
-linetoh_end_dtrace()
-{
-    return
-}
-
-linetoc_begin_dtrace()
-{
-    return
-}
-
-linetoc_dtrace()
-{
-    # No need for function definitions in dtrace backend
-    return
-}
-
-linetoc_end_dtrace()
-{
-    return
-}
-
-linetod_begin_dtrace()
-{
-    cat <<EOF
-provider qemu {
-EOF
-}
-
-linetod_dtrace()
-{
-    local name args
-    name=$(get_name "$1")
-    args=$(get_args "$1")
-
-    # DTrace provider syntax expects foo() for empty
-    # params, not foo(void)
-    if [ "$args" = "void" ]; then
-       args=""
-    fi
-
-    # Define prototype for probe arguments
-    cat <<EOF
-        probe $name($args);
-EOF
-}
-
-linetod_end_dtrace()
-{
-    cat <<EOF
-};
-EOF
-}
-
-linetostap_begin_dtrace()
-{
-    return
-}
-
-linetostap_dtrace()
-{
-    local i arg name args arglist
-    name=$(get_name "$1")
-    args=$(get_args "$1")
-    arglist=$(get_argnames "$1", "")
-
-    # Define prototype for probe arguments
-    cat <<EOF
-probe $probeprefix.$name = process("$binary").mark("$name")
-{
-EOF
-
-    i=1
-    for arg in $arglist
-    do
-        # 'limit' is a reserved keyword
-        if [ "$arg" = "limit" ]; then
-          arg="_limit"
-        fi
-        cat <<EOF
-  $arg = \$arg$i;
-EOF
-        i="$((i+1))"
-    done
-
-    cat <<EOF
-}
-EOF
-}
-
-linetostap_end_dtrace()
-{
-    return
-}
-
-# Process stdin by calling begin, line, and end functions for the backend
-convert()
-{
-    local begin process_line end str name NAME enabled
-    begin="lineto$1_begin_$backend"
-    process_line="lineto$1_$backend"
-    end="lineto$1_end_$backend"
-
-    "$begin"
-
-    while read -r str; do
-        # Skip comments and empty lines
-        test -z "${str%%#*}" && continue
-
-        echo
-        # Process the line.  The nop backend handles disabled lines.
-        if has_property "$str" "disable"; then
-            "lineto$1_nop" "$str"
-            enabled=0
-        else
-            "$process_line" "$str"
-            enabled=1
-        fi
-        if [ "$1" = "h" ]; then
-            name=$(get_name "$str")
-            NAME=$(echo $name | tr '[:lower:]' '[:upper:]')
-            echo "#define TRACE_${NAME}_ENABLED ${enabled}"
-        fi
-    done
-
-    echo
-    "$end"
-}
-
-tracetoh()
-{
-    cat <<EOF
-#ifndef TRACE_H
-#define TRACE_H
-
-/* This file is autogenerated by tracetool, do not edit. */
-
-#include "qemu-common.h"
-EOF
-    convert h
-    echo "#endif /* TRACE_H */"
-}
-
-tracetoc()
-{
-    echo "/* This file is autogenerated by tracetool, do not edit. */"
-    convert c
-}
-
-tracetod()
-{
-    if [ $backend != "dtrace" ]; then
-       echo "DTrace probe generator not applicable to $backend backend"
-       exit 1
-    fi
-    echo "/* This file is autogenerated by tracetool, do not edit. */"
-    convert d
-}
-
-tracetostap()
-{
-    if [ $backend != "dtrace" ]; then
-       echo "SystemTAP tapset generator not applicable to $backend backend"
-       exit 1
-    fi
-    if [ -z "$binary" ]; then
-       echo "--binary is required for SystemTAP tapset generator"
-       exit 1
-    fi
-    if [ -z "$probeprefix" -a -z "$targettype" ]; then
-       echo "--target-type is required for SystemTAP tapset generator"
-       exit 1
-    fi
-    if [ -z "$probeprefix" -a -z "$targetarch" ]; then
-       echo "--target-arch is required for SystemTAP tapset generator"
-       exit 1
-    fi
-    if [ -z "$probeprefix" ]; then
-        probeprefix="qemu.$targettype.$targetarch";
-    fi
-    echo "/* This file is autogenerated by tracetool, do not edit. */"
-    convert stap
-}
-
-
-backend=
-output=
-binary=
-targettype=
-targetarch=
-probeprefix=
-
-
-until [ -z "$1" ]
-do
-  case "$1" in
-    "--nop" | "--simple" | "--stderr" | "--ust" | "--dtrace") backend="${1#--}" ;;
-
-    "--binary") shift ; binary="$1" ;;
-    "--target-arch") shift ; targetarch="$1" ;;
-    "--target-type") shift ; targettype="$1" ;;
-    "--probe-prefix") shift ; probeprefix="$1" ;;
-
-    "-h" | "-c" | "-d") output="${1#-}" ;;
-    "--stap") output="${1#--}" ;;
-
-    "--check-backend") exit 0 ;; # used by ./configure to test for backend
-
-    "--list-backends") # used by ./configure to list available backends
-          echo "nop simple stderr ust dtrace"
-          exit 0
-          ;;
-
-    *)
-      usage;;
-  esac
-  shift
-done
-
-if [ "$backend" = "" -o "$output" = "" ]; then
-  usage
-fi
-
-gen="traceto$output"
-"$gen"
-
-exit 0
diff --git a/scripts/tracetool.py b/scripts/tracetool.py
new file mode 100755
index 0000000..fe2ea34
--- /dev/null
+++ b/scripts/tracetool.py
@@ -0,0 +1,108 @@ 
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+Command-line wrapper for the tracetool machinery.
+"""
+
+__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"
+
+
+import sys
+import getopt
+
+from tracetool import error_write, out
+import tracetool.backend
+import tracetool.format
+
+
+_SCRIPT = ""
+
+def error_opt(msg = None):
+    if msg is not None:
+        error_write("Error: " + msg + "\n")
+
+    backend_descr = "\n".join([ "    %-15s %s" % (n, d)
+                                for n,d in tracetool.backend.get_list() ])
+    format_descr = "\n".join([ "    %-15s %s" % (n, d)
+                               for n,d in tracetool.format.get_list() ])
+    error_write("""\
+Usage: %(script)s --format=<format> --backend=<backend> [<options>]
+
+Backends:
+%(backends)s
+
+Formats:
+%(formats)s
+
+Options:
+    --help                   This help message.
+    --list-backends          Print list of available backends.
+    --check-backend          Check if the given backend is valid.
+""" % {
+            "script" : _SCRIPT,
+            "backends" : backend_descr,
+            "formats" : format_descr,
+            })
+
+    if msg is None:
+        sys.exit(0)
+    else:
+        sys.exit(1)
+
+
+def main(args):
+    global _SCRIPT
+    _SCRIPT = args[0]
+
+    long_opts  = [ "backend=", "format=", "help", "list-backends", "check-backend" ]
+    long_opts += [ "binary=", "target-type=", "target-arch=", "probe-prefix=" ]
+
+    try:
+        opts, args = getopt.getopt(args[1:], "", long_opts)
+    except getopt.GetoptError as err:
+        error_opt(str(err))
+
+    check_backend = False
+    arg_backend = ""
+    arg_format = ""
+    for opt, arg in opts:
+        if opt == "--help":
+            error_opt()
+
+        elif opt == "--backend":
+            arg_backend = arg
+        elif opt == "--format":
+            arg_format = arg
+
+        elif opt == "--list-backends":
+            backends = tracetool.backend.get_list()
+            out(", ".join([ b for b,_ in backends ]))
+            sys.exit(0)
+        elif opt == "--check-backend":
+            check_backend = True
+
+        else:
+            error_opt("unhandled option: %s" % opt)
+
+    if arg_backend is None:
+        error_opt("backend not set")
+
+    if check_backend:
+        if tracetool.backend.exists(arg_backend):
+            sys.exit(0)
+        else:
+            sys.exit(1)
+
+    try:
+        tracetool.generate(sys.stdin, arg_format, arg_backend)
+    except tracetool.TracetoolError as e:
+        error_opt(str(e))
+
+if __name__ == "__main__":
+    main(sys.argv)
diff --git a/scripts/tracetool/__init__.py b/scripts/tracetool/__init__.py
new file mode 100644
index 0000000..1719bb4
--- /dev/null
+++ b/scripts/tracetool/__init__.py
@@ -0,0 +1,262 @@ 
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+Machinery for generating tracing-related intermediate files.
+"""
+
+__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"
+
+
+import re
+import sys
+
+import tracetool.format
+import tracetool.backend
+
+
+def error_write(*lines):
+    """Write a set of error lines."""
+    sys.stderr.writelines("\n".join(lines) + "\n")
+
+def error(*lines):
+    """Write a set of error lines and exit."""
+    error_write(*lines)
+    sys.exit(1)
+
+
+def out(*lines, **kwargs):
+    """Write a set of output lines.
+
+    You can use kwargs as a shorthand for mapping variables when formating all
+    the strings in lines.
+    """
+    lines = [ l % kwargs for l in lines ]
+    sys.stdout.writelines("\n".join(lines) + "\n")
+
+
+class Arguments:
+    """Event arguments description."""
+
+    def __init__(self, args):
+        """
+        Parameters
+        ----------
+        args :
+            List of (type, name) tuples.
+        """
+        self._args = args
+
+    @staticmethod
+    def build(arg_str):
+        """Build and Arguments instance from an argument string.
+
+        Parameters
+        ----------
+        arg_str : str
+            String describing the event arguments.
+        """
+        res = []
+        for arg in arg_str.split(","):
+            arg = arg.strip()
+            parts = arg.split()
+            head, sep, tail = parts[-1].rpartition("*")
+            parts = parts[:-1]
+            if tail == "void":
+                assert len(parts) == 0 and sep == ""
+                continue
+            arg_type = " ".join(parts + [ " ".join([head, sep]).strip() ]).strip()
+            res.append((arg_type, tail))
+        return Arguments(res)
+
+    def __iter__(self):
+        """Iterate over the (type, name) pairs."""
+        return iter(self._args)
+
+    def __len__(self):
+        """Number of arguments."""
+        return len(self._args)
+
+    def __str__(self):
+        """String suitable for declaring function arguments."""
+        if len(self._args) == 0:
+            return "void"
+        else:
+            return ", ".join([ " ".join([t, n]) for t,n in self._args ])
+
+    def __repr__(self):
+        """Evaluable string representation for this object."""
+        return "Arguments(\"%s\")" % str(self)
+
+    def names(self):
+        """List of argument names."""
+        return [ name for _, name in self._args ]
+
+    def types(self):
+        """List of argument types."""
+        return [ type_ for type_, _ in self._args ]
+
+
+class Event(object):
+    """Event description.
+
+    Attributes
+    ----------
+    name : str
+        The event name.
+    fmt : str
+        The event format string.
+    properties : set(str)
+        Properties of the event.
+    args : Arguments
+        The event arguments.
+    """
+
+    _CRE = re.compile("((?P<props>.*)\s+)?(?P<name>[^(\s]+)\((?P<args>[^)]*)\)\s*(?P<fmt>\".*)?")
+
+    _VALID_PROPS = set(["disable"])
+
+    def __init__(self, name, props, fmt, args):
+        """
+        Parameters
+        ----------
+        name : string
+            Event name.
+        props : list of str
+            Property names.
+        fmt : str
+            Event printing format.
+        args : Arguments
+            Event arguments.
+        """
+        self.name = name
+        self.properties = props
+        self.fmt = fmt
+        self.args = args
+
+        unknown_props = set(self.properties) - self._VALID_PROPS
+        if len(unknown_props) > 0:
+            raise ValueError("Unknown properties: %s" % ", ".join(unknown_props))
+
+    @staticmethod
+    def build(line_str):
+        """Build an Event instance from a string.
+
+        Parameters
+        ----------
+        line_str : str
+            Line describing the event.
+        """
+        m = Event._CRE.match(line_str)
+        assert m is not None
+        groups = m.groupdict('')
+
+        name = groups["name"]
+        props = groups["props"].split()
+        fmt = groups["fmt"]
+        args = Arguments.build(groups["args"])
+
+        return Event(name, props, fmt, args)
+
+    def __repr__(self):
+        """Evaluable string representation for this object."""
+        return "Event('%s %s(%s) %s')" % (" ".join(self.properties),
+                                          self.name,
+                                          self.args,
+                                          self.fmt)
+
+def _read_events(fobj):
+    res = []
+    for line in fobj:
+        if not line.strip():
+            continue
+        if line.lstrip().startswith('#'):
+            continue
+        res.append(Event.build(line))
+    return res
+
+
+class TracetoolError (Exception):
+    """Exception for calls to generate."""
+    pass
+
+
+def try_import(mod_name, attr_name = None, attr_default = None):
+    """Try to import a module and get an attribute from it.
+
+    Parameters
+    ----------
+    mod_name : str
+        Module name.
+    attr_name : str, optional
+        Name of an attribute in the module.
+    attr_default : optional
+        Default value if the attribute does not exist in the module.
+
+    Returns
+    -------
+    A pair indicating whether the module could be imported and the module or
+    object or attribute value.
+    """
+    try:
+        module = __import__(mod_name, fromlist=["__package__"])
+        if attr_name is None:
+            return True, module
+        return True, getattr(module, str(attr_name), attr_default)
+    except ImportError:
+        return False, None
+
+
+def generate(fevents, format, backend):
+    """Generate the output for the given (format, backend) pair.
+
+    Parameters
+    ----------
+    fevents : file
+        Event description file.
+    format : str
+        Output format name.
+    backend : str
+        Output backend name.
+    """
+    # fix strange python error (UnboundLocalError tracetool)
+    import tracetool
+
+    format = str(format)
+    if len(format) is 0:
+        raise TracetoolError("format not set")
+    mformat = format.replace("-", "_")
+    if not tracetool.format.exists(mformat):
+        raise TracetoolError("unknown format: %s" % format)
+
+    backend = str(backend)
+    if len(backend) is 0:
+        raise TracetoolError("backend not set")
+    mbackend = backend.replace("-", "_")
+    if not tracetool.backend.exists(mbackend):
+        raise TracetoolError("unknown backend: %s" % backend)
+
+    if not tracetool.backend.compatible(mbackend, mformat):
+        raise TracetoolError("backend '%s' not compatible with format '%s'" %
+                             (backend, format))
+
+    events = _read_events(fevents)
+
+    if backend == "nop":
+        ( e.properies.add("disable") for e in events )
+
+    tracetool.format.generate_begin(mformat, events)
+    tracetool.backend.generate("nop", format,
+                               [ e
+                                 for e in events
+                                 if "disable" in e.properties ])
+    tracetool.backend.generate(backend, format,
+                               [ e
+                                 for e in events
+                                 if "disable" not in e.properties ])
+    tracetool.format.generate_end(mformat, events)
diff --git a/scripts/tracetool/backend/__init__.py b/scripts/tracetool/backend/__init__.py
new file mode 100644
index 0000000..34b7ed8
--- /dev/null
+++ b/scripts/tracetool/backend/__init__.py
@@ -0,0 +1,111 @@ 
+#!/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 functions
+-----------------
+
+======== =======================================================================
+Function Description
+======== =======================================================================
+<format> Called to generate the format- and backend-specific code for each of
+         the specified events. If the function does not exist, the backend is
+         considered not compatible with the given format.
+======== =======================================================================
+"""
+
+__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"
+
+
+import pkgutil
+
+import tracetool
+
+
+def get_list():
+    """Get a list of (name, description) pairs."""
+    res = [("nop", "Tracing disabled.")]
+    for _, modname, _ in pkgutil.iter_modules(tracetool.backend.__path__):
+        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]
+
+        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]
+
+
+def compatible(backend, format):
+    """Whether a backend is compatible with the given format."""
+    if not exists(backend):
+        raise ValueError("unknown backend: %s" % backend)
+
+    backend = backend.replace("-", "_")
+    format = format.replace("-", "_")
+
+    if backend == "nop":
+        return True
+    else:
+        func = tracetool.try_import("tracetool.backend." + backend,
+                                    format, None)[1]
+        return func is not None
+
+
+def _empty(events):
+    pass
+
+def generate(backend, format, events):
+    """Generate the per-event output for the given (backend, format) pair."""
+    if not compatible(backend, format):
+        raise ValueError("backend '%s' not compatible with format '%s'" %
+                         (backend, format))
+
+    backend = backend.replace("-", "_")
+    format = format.replace("-", "_")
+
+    if backend == "nop":
+        func = tracetool.try_import("tracetool.format." + format,
+                                    "nop", _empty)[1]
+    else:
+        func = tracetool.try_import("tracetool.backend." + backend,
+                                    format, None)[1]
+
+    func(events)
diff --git a/scripts/tracetool/format/__init__.py b/scripts/tracetool/format/__init__.py
new file mode 100644
index 0000000..0e4baf0
--- /dev/null
+++ b/scripts/tracetool/format/__init__.py
@@ -0,0 +1,99 @@ 
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+Format management.
+
+
+Creating new formats
+--------------------
+
+A new format named 'foo-bar' corresponds to Python module
+'tracetool/format/foo_bar.py'.
+
+A format module should provide a docstring, whose first non-empty line will be
+considered its short description.
+
+All formats must generate their contents through the 'tracetool.out' routine.
+
+
+Format functions
+----------------
+
+All the following functions are optional, and no output will be generated if
+they do not exist.
+
+======== =======================================================================
+Function Description
+======== =======================================================================
+begin    Called to generate the format-specific file header.
+end      Called to generate the format-specific file footer.
+nop      Called to generate the per-event contents when the event is disabled or
+         the selected backend is 'nop'.
+======== =======================================================================
+"""
+
+__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"
+
+
+import pkgutil
+
+import tracetool
+
+
+def get_list():
+    """Get a list of (name, description) pairs."""
+    res = []
+    for _, modname, _ in pkgutil.iter_modules(tracetool.format.__path__):
+        module = tracetool.try_import("tracetool.format." + modname)
+
+        # just in case; should never fail unless non-module files are put there
+        if not module[0]:
+            continue
+        module = module[1]
+
+        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 format exists."""
+    if len(name) == 0:
+        return False
+    name = name.replace("-", "_")
+    return tracetool.try_import("tracetool.format." + name)[1]
+
+
+def _empty(events):
+    pass
+
+def generate_begin(name, events):
+    """Generate the header of the format-specific file."""
+    if not exists(name):
+        raise ValueError("unknown format: %s" % name)
+
+    name = name.replace("-", "_")
+    func = tracetool.try_import("tracetool.format." + name,
+                                "begin", _empty)[1]
+    func(events)
+
+def generate_end(name, events):
+    """Generate the footer of the format-specific file."""
+    if not exists(name):
+        raise ValueError("unknown format: %s" % name)
+
+    name = name.replace("-", "_")
+    func = tracetool.try_import("tracetool.format." + name,
+                                "end", _empty)[1]
+    func(events)