From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Mon, 5 Nov 2012 07:48:29 +0000 (+0100)
Subject: trace: document '-' syntax for disabling events
X-Git-Tag: cpu-hotplug-port-v2~38^2~1
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=8f5a0fb1f4e3167b893e3a4272446e2cf1568058;p=people%2Faperard%2Fqemu-dm.git

trace: document '-' syntax for disabling events

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---

diff --git a/docs/tracing.txt b/docs/tracing.txt
index c541133368..79014093db 100644
--- a/docs/tracing.txt
+++ b/docs/tracing.txt
@@ -139,6 +139,10 @@ having a common prefix in a batch. For example, virtio-blk trace events could
 be enabled using:
   trace-event virtio_blk_* on
 
+If a line in the "-trace events=<file>" file begins with a '-', the trace event
+will be disabled instead of enabled.  This is useful when a wildcard was used
+to enable an entire family of events but one noisy event needs to be disabled.
+
 == Trace backends ==
 
 The "tracetool" script automates tedious trace event code generation and also