docs/tracing.txt: Update documentation of default backend
In commit baf86d6b3c we switched the default trace backend from "nop"
to "log". Update the documentation to match.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1478276837-31780-1-git-send-email-peter.maydell@linaro.org
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/docs/tracing.txt b/docs/tracing.txt
index e62444c..f351998a 100644
--- a/docs/tracing.txt
+++ b/docs/tracing.txt
@@ -150,13 +150,16 @@
For a list of supported trace backends, try ./configure --help or see below.
If multiple backends are enabled, the trace is sent to them all.
+If no backends are explicitly selected, configure will default to the
+"log" backend.
+
The following subsections describe the supported trace backends.
=== Nop ===
The "nop" backend generates empty trace event functions so that the compiler
-can optimize out trace events completely. This is the default and imposes no
-performance penalty.
+can optimize out trace events completely. This imposes no performance
+penalty.
Note that regardless of the selected trace backend, events with the "disable"
property will be generated with the "nop" backend.
