[PATCH v3.1 3/8] Documentation: tracing: Add tracing_on option to boot-time tracer

[Masami Hiramatsu <mhiramat@xxxxxxxxxx>]

Add tracing_on option description to the boot-time tracer.

Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
---
 Changes in v3.1:
   - Fix "on boot" to "on starting boot-time tracing".
---
 Documentation/trace/boottime-trace.rst |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Documentation/trace/boottime-trace.rst b/Documentation/trace/boottime-trace.rst
index dcb390075ca1..9bc8aceb8c0a 100644
--- a/Documentation/trace/boottime-trace.rst
+++ b/Documentation/trace/boottime-trace.rst
@@ -61,6 +61,10 @@ These options can be used for each instance including global ftrace node.
 ftrace.[instance.INSTANCE.]options = OPT1[, OPT2[...]]
    Enable given ftrace options.
 
+ftrace.[instance.INSTANCE.]tracing_on = 0|1
+   Enable/Disable tracing on this instance when starting boot-time tracing.
+   (you can enable it by the "traceon" event trigger action)
+
 ftrace.[instance.INSTANCE.]trace_clock = CLOCK
    Set given CLOCK to ftrace's trace_clock.