[PATCH 3/3] perf: Add doc when no conversion support compiled

[GeneviÃve Bastien]

This adds documentation on the environment variables needed to the
message telling that no conversion support is compiled in.

Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Julien Desfossez <jdesfossez@xxxxxxxxxxxx>
Cc: Francis Deslauriers <francis.deslauriers@xxxxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: GeneviÃve Bastien <gbastien@xxxxxxxxxxxx>
Signed-off-by: GeneviÃve Bastien <gbastien@xxxxxxxxxxxx>
---
 tools/perf/builtin-data.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/builtin-data.c b/tools/perf/builtin-data.c
index 0adb5f82335a..46cd8490baf4 100644
--- a/tools/perf/builtin-data.c
+++ b/tools/perf/builtin-data.c
@@ -69,7 +69,7 @@ static int cmd_data_convert(int argc, const char **argv)
 	};
 
 #ifndef HAVE_LIBBABELTRACE_SUPPORT
-	pr_err("No conversion support compiled in.\n");
+	pr_err("No conversion support compiled in. perf should be compiled with environment variables LIBBABELTRACE=1 and LIBBABELTRACE_DIR=/path/to/libbabeltrace/\n");
 	return -1;
 #endif
 
-- 
2.13.3