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From:   James Clark <james.clark@arm.com>
To:     linux-perf-users@vger.kernel.org, radhey.shyam.pandey@amd.com
Cc:     coresight@lists.linaro.org, James Clark <james.clark@arm.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Ian Rogers <irogers@google.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <uwe@kleine-koenig.org>,
        linux-kernel@vger.kernel.org
Subject: [PATCH] perf build: Fix library not found error when using CSLIBS
Date:   Fri,  7 Jul 2023 16:45:46 +0100
Message-Id: <20230707154546.456720-1-james.clark@arm.com>
MIME-Version: 1.0
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-L only specifies the search path for libraries directly provided in the
link line with -l. Because -lopencsd isn't specified, it's only linked
because it's a dependency of -lopencsd_c_api. Dependencies like this are
resolved using the default system search paths or -rpath-link=... rather
than -L. This means that compilation only works if OpenCSD is installed
to the system rather than provided with the CSLIBS (-L) option.

This could be fixed by adding -Wl,-rpath-link=$(CSLIBS) but that is less
conventional than just adding -lopencsd to the link line so that it uses
-L. -lopencsd seems to have been removed in commit ed17b1914978 ("perf
tools: Drop requirement for libstdc++.so for libopencsd check") because
it was thought that there was a chance compilation would work even if it
didn't exist, but I think that only applies to libstdc++ so there is no
harm to add it back. libopencsd.so and libopencsd_c_api.so would always
exist together.

Testing
=======

The following scenarios now all work:

 * Cross build with OpenCSD installed
 * Cross build using CSLIBS=...
 * Native build with OpenCSD installed
 * Native build using CSLIBS=...
 * Static cross build with OpenCSD installed
 * Static cross build with CSLIBS=...

Reported-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
Closes: https://lore.kernel.org/linux-arm-kernel/56905d7a-a91e-883a-b707-9d5f686ba5f1@arm.com/
Link: https://lore.kernel.org/all/36cc4dc6-bf4b-1093-1c0a-876e368af183@kleine-koenig.org/
Fixes: ed17b1914978 ("perf tools: Drop requirement for libstdc++.so for libopencsd check")
Signed-off-by: James Clark <james.clark@arm.com>
---
 tools/perf/Makefile.config | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 0609c19caabd..c5db0de49868 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -155,9 +155,9 @@ FEATURE_CHECK_LDFLAGS-libcrypto = -lcrypto
 ifdef CSINCLUDES
   LIBOPENCSD_CFLAGS := -I$(CSINCLUDES)
 endif
-OPENCSDLIBS := -lopencsd_c_api
+OPENCSDLIBS := -lopencsd_c_api -lopencsd
 ifeq ($(findstring -static,${LDFLAGS}),-static)
-  OPENCSDLIBS += -lopencsd -lstdc++
+  OPENCSDLIBS += -lstdc++
 endif
 ifdef CSLIBS
   LIBOPENCSD_LDFLAGS := -L$(CSLIBS)
-- 
2.34.1