diff --git a/tools/perf/Documentation/perf-intel-pt.txt b/tools/perf/Documentation/perf-intel-pt.txt
index 5415c4993c6b..de63c418e4d1 100644
--- a/tools/perf/Documentation/perf-intel-pt.txt
+++ b/tools/perf/Documentation/perf-intel-pt.txt
@@ -1526,6 +1526,36 @@ Can be compiled and traced:
  $
 
 
+Pipe mode
+---------
+Pipe mode is a problem for Intel PT and possibly other auxtrace users.
+It's not recommended to use a pipe as data output with Intel PT because
+of the following reason.
+
+Essentially the auxtrace buffers do not behave like the regular perf
+event buffers.  That is because the head and tail are updated by
+software, but in the auxtrace case the data is written by hardware.
+So the head and tail do not get updated as data is written.
+
+In the Intel PT case, the head and tail are updated only when the trace
+is disabled by software, for example:
+    - full-trace, system wide : when buffer passes watermark
+    - full-trace, not system-wide : when buffer passes watermark or
+                                    context switches
+    - snapshot mode : as above but also when a snapshot is made
+    - sample mode : as above but also when a sample is made
+
+That means finished-round ordering doesn't work.  An auxtrace buffer
+can turn up that has data that extends back in time, possibly to the
+very beginning of tracing.
+
+For a perf.data file, that problem is solved by going through the trace
+and queuing up the auxtrace buffers in advance.
+
+For pipe mode, the order of events and timestamps can presumably
+be messed up.
+
+
 EXAMPLE
 -------
 
diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
index 0ef4cbf21e62..344b65a8f768 100644
--- a/tools/perf/util/auxtrace.c
+++ b/tools/perf/util/auxtrace.c
@@ -1107,6 +1107,9 @@ int auxtrace_queue_data(struct perf_session *session, bool samples, bool events)
 	if (auxtrace__dont_decode(session))
 		return 0;
 
+	if (perf_data__is_pipe(session->data))
+		return 0;
+
 	if (!session->auxtrace || !session->auxtrace->queue_data)
 		return -EINVAL;
 
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index 89863efedc82..7a2ce387079e 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -3942,6 +3942,12 @@ int intel_pt_process_auxtrace_info(union perf_event *event,
 
 	intel_pt_setup_pebs_events(pt);
 
+	if (perf_data__is_pipe(session->data)) {
+		pr_warning("WARNING: Intel PT with pipe mode is not recommended.\n"
+			   "         The output cannot relied upon.  In particular,\n"
+			   "         timestamps and the order of events may be incorrect.\n");
+	}
+
 	if (pt->sampling_mode || list_empty(&session->auxtrace_index))
 		err = auxtrace_queue_data(session, true, true);
 	else