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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jin Yao <yao.jin@linux.intel.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Andi Kleen <ak@linux.intel.com>, Jiri Olsa <jolsa@kernel.org>,
        Kan Liang <kan.liang@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 034/171] perf report: Add warning when libunwind not compiled in
Date:   Thu,  2 Jan 2020 23:06:05 +0100
Message-Id: <20200102220551.746426321@linuxfoundation.org>
In-Reply-To: <20200102220546.960200039@linuxfoundation.org>
References: <20200102220546.960200039@linuxfoundation.org>
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From: Jin Yao <yao.jin@linux.intel.com>

[ Upstream commit 800d3f561659b5436f8c57e7c26dd1f6928b5615 ]

We received a user report that call-graph DWARF mode was enabled in
'perf record' but 'perf report' didn't unwind the callstack correctly.
The reason was, libunwind was not compiled in.

We can use 'perf -vv' to check the compiled libraries but it would be
valuable to report a warning to user directly (especially valuable for
a perf newbie).

The warning is:

Warning:
Please install libunwind development packages during the perf build.

Both TUI and stdio are supported.

Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191011022122.26369-1-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/perf/builtin-report.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 6e88460cd13d..33ff5c843346 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -292,6 +292,13 @@ static int report__setup_sample_type(struct report *rep)
 				PERF_SAMPLE_BRANCH_ANY))
 		rep->nonany_branch_mode = true;
 
+#ifndef HAVE_LIBUNWIND_SUPPORT
+	if (dwarf_callchain_users) {
+		ui__warning("Please install libunwind development packages "
+			    "during the perf build.\n");
+	}
+#endif
+
 	return 0;
 }
 
-- 
2.20.1