[Qemu-devel] [PATCH] trace: document '-' syntax for disabling events

[Stefan Hajnoczi]

Signed-off-by: Stefan Hajnoczi <address@hidden>
---
 docs/tracing.txt | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/docs/tracing.txt b/docs/tracing.txt
index c541133..7901409 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
-- 
1.7.12.1