trace: Multi-backend tracing

Adds support to compile QEMU with multiple tracing backends at the same time.

For example, you can compile QEMU with:

  $ ./configure --enable-trace-backends=ftrace,dtrace

Where 'ftrace' can be handy for having an in-flight record of events, and 'dtrace' can be later used to extract more information from the system.

This patch allows having both available without recompiling QEMU.

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

1 files changed, 22 insertions, 21 deletions

diff --git a/scripts/tracetool.py b/scripts/tracetool.py
index 5f4890f3ab..83bde7bda9 100755
--- a/scripts/tracetool.py
+++ b/scripts/tracetool.py
@@ -6,7 +6,7 @@ Command-line wrapper for the tracetool machinery.
 """
 
 __author__     = "Lluís Vilanova <vilanova@ac.upc.edu>"
-__copyright__  = "Copyright 2012, 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"
@@ -32,7 +32,7 @@ def error_opt(msg = None):
     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>]
+Usage: %(script)s --format=<format> --backends=<backends> [<options>]
 
 Backends:
 %(backends)s
@@ -43,7 +43,7 @@ Formats:
 Options:
     --help                   This help message.
     --list-backends          Print list of available backends.
-    --check-backend          Check if the given backend is valid.
+    --check-backends         Check if the given backend is valid.
     --binary <path>          Full path to QEMU binary.
     --target-type <type>     QEMU emulator target type ('system' or 'user').
     --target-name <name>     QEMU emulator target name.
@@ -65,16 +65,17 @@ def main(args):
     global _SCRIPT
     _SCRIPT = args[0]
 
-    long_opts  = [ "backend=", "format=", "help", "list-backends", "check-backend" ]
-    long_opts += [ "binary=", "target-type=", "target-name=", "probe-prefix=" ]
+    long_opts = ["backends=", "format=", "help", "list-backends",
+                 "check-backends"]
+    long_opts += ["binary=", "target-type=", "target-name=", "probe-prefix="]
 
     try:
         opts, args = getopt.getopt(args[1:], "", long_opts)
     except getopt.GetoptError, err:
         error_opt(str(err))
 
-    check_backend = False
-    arg_backend = ""
+    check_backends = False
+    arg_backends = []
     arg_format = ""
     binary = None
     target_type = None
@@ -84,8 +85,8 @@ def main(args):
         if opt == "--help":
             error_opt()
 
-        elif opt == "--backend":
-            arg_backend = arg
+        elif opt == "--backends":
+            arg_backends = arg.split(",")
         elif opt == "--format":
             arg_format = arg
 
@@ -93,8 +94,8 @@ def main(args):
             public_backends = tracetool.backend.get_list(only_public = True)
             out(", ".join([ b for b,_ in public_backends ]))
             sys.exit(0)
-        elif opt == "--check-backend":
-            check_backend = True
+        elif opt == "--check-backends":
+            check_backends = True
 
         elif opt == "--binary":
             binary = arg
@@ -108,14 +109,14 @@ def main(args):
         else:
             error_opt("unhandled option: %s" % opt)
 
-    if arg_backend is None:
-        error_opt("backend not set")
+    if len(arg_backends) == 0:
+        error_opt("no backends specified")
 
-    if check_backend:
-        if tracetool.backend.exists(arg_backend):
-            sys.exit(0)
-        else:
-            sys.exit(1)
+    if check_backends:
+        for backend in arg_backends:
+            if not tracetool.backend.exists(backend):
+                sys.exit(1)
+        sys.exit(0)
 
     if arg_format == "stap":
         if binary is None:
@@ -126,11 +127,11 @@ def main(args):
             error_opt("--target-name is required for SystemTAP tapset generator")
 
         if probe_prefix is None:
-            probe_prefix = ".".join([ "qemu", target_type, target_name ])
+            probe_prefix = ".".join(["qemu", target_type, target_name])
 
     try:
-        tracetool.generate(sys.stdin, arg_format, arg_backend,
-                           binary = binary, probe_prefix = probe_prefix)
+        tracetool.generate(sys.stdin, arg_format, arg_backends,
+                           binary=binary, probe_prefix=probe_prefix)
     except tracetool.TracetoolError, e:
         error_opt(str(e))