add note how to run valgrind tests without libunwind

Author: lukaszstolarczuk

CMakeLists.txt

@@ -78,7 +78,7 @@ option(CHECK_CPP_STYLE "check code style of C++ sources" OFF)
 option(TRACE_TESTS "more verbose test outputs" OFF)
 option(USE_ASAN "enable AddressSanitizer (debugging)" OFF)
 option(USE_UBSAN "enable UndefinedBehaviorSanitizer (debugging)" OFF)
-option(USE_LIBUNWIND "use libunwind for more reliable stack traces from tests (if available)" ON)
+option(USE_LIBUNWIND "use libunwind for more reliable stack traces from tests (if available); see README file if tests fail with libunwind" ON)
 option(USE_CCACHE "use ccache if it is available in the system" ON)
 
 option(TESTS_USE_FORCED_PMEM "run tests with PMEM_IS_PMEM_FORCE=1 - it speeds up tests execution on emulated pmem" OFF)

README.md

@@ -97,6 +97,24 @@ $ make
 # make install
 ```
 
+**Note:**
+By default CMake's option `USE_LIBUNWIND` is switched ON. If libunwind package was found
+in the system, it is then linked to all tests' binaries. Sometimes this may lead to
+failing a test, if it is run under Valgrind. To avoid this false-positive fails, you can
+execute tests run under Valgrind separately, without libunwind:
+
+```sh
+cmake .. -DTESTS_USE_VALGRIND=ON -DUSE_LIBUNWIND=OFF && \
+ctest -R "_helgrind|_pmemcheck|_drd|_memcheck|_pmreorder"	# run only valgrind tests
+```
+
+or valgrind tests can be disabled in CMake build:
+
+```sh
+cmake .. -DTESTS_USE_VALGRIND=OFF && \
+ctest
+```
+
 ### Developer compilation
 ```sh
 $ mkdir build

utils/docker/run-build.sh

@@ -23,7 +23,7 @@ TESTS_PACKAGES=${TESTS_PACKAGES:-ON}
 TESTS_USE_FORCED_PMEM=${TESTS_USE_FORCED_PMEM:-ON}
 TESTS_ASAN=${TESTS_ASAN:-OFF}
 TESTS_UBSAN=${TESTS_UBSAN:-OFF}
-TESTS_VALGRIND_UNWIND=${TESTS_VALGRIND_UNWIND:-OFF}
+TESTS_VALGRIND_UNWIND=${TESTS_VALGRIND_UNWIND:-OFF} # turn unwind off, when building with valgrind tests=ON
 TEST_TIMEOUT=${TEST_TIMEOUT:-600}
 
 export PMREORDER_STACKTRACE_DEPTH=20