From:   James Clark <james.clark@arm.com>
To:     linux-perf-users@vger.kernel.org, acme@kernel.org
Cc:     linux-kernel@vger.kernel.org, James Clark <james.clark@arm.com>,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Mike Leach <mike.leach@linaro.org>,
        Leo Yan <leo.yan@linaro.org>,
        John Garry <john.g.garry@oracle.com>,
        Will Deacon <will@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>, coresight@lists.linaro.org,
        linux-arm-kernel@lists.infradead.org
Subject: [PATCH] perf: cs-etm: Improve missing sink warning message
Date:   Mon, 23 Jan 2023 16:11:14 +0000
Message-Id: <20230123161114.261255-1-james.clark@arm.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Make the sink error message more similar to the event error message that
reminds about missing kernel support. The available sinks are also
determined by the hardware so mention that too.

Also, usually it's not necessary to specify the sink, so add that as a
hint.

Now the error for a made up sink looks like this:

  $ perf record -e cs_etm/@abc/
  Couldn't find sink "abc" on event cs_etm/@abc/.
  Missing kernel or device support? Errno: 2 (No such file or directory)

  Hint: An appropriate sink will picked automatically if none is specified.

Signed-off-by: James Clark <james.clark@arm.com>
---
 tools/perf/arch/arm/util/cs-etm.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/arch/arm/util/cs-etm.c b/tools/perf/arch/arm/util/cs-etm.c
index 481e170cd3f1..c6195a7a3cbf 100644
--- a/tools/perf/arch/arm/util/cs-etm.c
+++ b/tools/perf/arch/arm/util/cs-etm.c
@@ -283,7 +283,9 @@ static int cs_etm_set_sink_attr(struct perf_pmu *pmu,
 
 		ret = perf_pmu__scan_file(pmu, path, "%x", &hash);
 		if (ret != 1) {
-			pr_err("failed to set sink \"%s\" on event %s with %d (%s)\n",
+			pr_err("Couldn't find sink \"%s\" on event %s\n"
+			       "Missing kernel or device support? errno: %d (%s)\n\n"
+			       "Hint: An appropriate sink will picked automatically if one isn't specified.\n",
 			       sink, evsel__name(evsel), errno,
 			       str_error_r(errno, msg, sizeof(msg)));
 			return ret;

base-commit: 5670ebf54bd26482f57a094c53bdc562c106e0a9
-- 
2.39.1