From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Petazzoni Date: Wed, 5 Sep 2018 09:19:10 +0200 Subject: [Buildroot] [PATCH v2, 1/1] boost: fix static detection of lock-free atomic ints In-Reply-To: <20180904222820.22186-1-fontaine.fabrice@gmail.com> References: <20180904222820.22186-1-fontaine.fabrice@gmail.com> Message-ID: <20180905091910.535af5d3@windsurf> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net Hello, Thanks for investigating this issue, I know what it takes to dive into the Boost build system, however, I am a bit confused by what's happening. On Wed, 5 Sep 2018 00:28:20 +0200, Fabrice Fontaine wrote: > When build statically, boost is unable to detect lock-free atomics ints > because it tries to link dynamically, see > output/build/boost-1.67.0/bin.v2/config.log (with -d5 option): > > Using shell: /bin/sh -c > argv[0] = '/bin/sh' > argv[1] = '-c' > argv[2] = ' > "/home/fabrice/buildroot/output/host/bin/arm-linux-g++" -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -Wl,-elf2flt -static -Wl,-elf2flt -static -fPIC -pthread -O0 -fno-inline -Wall -pedantic -g -Wextra -Wno-long-long -Wno-unused-parameter -Wunused-function -pedantic -DBOOST_ALL_NO_LIB=1 -DBOOST_SYSTEM_DYN_LINK=1 -DBOOST_THREAD_BUILD_DLL=1 -I"." -c -o "bin.v2/libs/thread/build/gcc-6.4.0/debug/threading-multi/has_atomic_flag_lockfree_test.o" "libs/thread/src/../build/has_atomic_flag_lockfree_test.cpp" > ' > gcc.compile.c++ bin.v2/libs/thread/build/gcc-6.4.0/debug/threading-multi/has_atomic_flag_lockfree_test.o > > "/home/fabrice/buildroot/output/host/bin/arm-linux-g++" -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -Wl,-elf2flt -static -Wl,-elf2flt -static -fPIC -pthread -O0 -fno-inline -Wall -pedantic -g -Wextra -Wno-long-long -Wno-unused-parameter -Wunused-function -pedantic -DBOOST_ALL_NO_LIB=1 -DBOOST_SYSTEM_DYN_LINK=1 -DBOOST_THREAD_BUILD_DLL=1 -I"." -c -o "bin.v2/libs/thread/build/gcc-6.4.0/debug/threading-multi/has_atomic_flag_lockfree_test.o" "libs/thread/src/../build/has_atomic_flag_lockfree_test.cpp" So here, it is compiling (no linking) the has_atomic_flag_lockfree_test.cpp test file into its corresponding object file. It does not use -shared at this point. > 0.033561 sec system; 0.126314 sec user; 288.682473 sec clock > gcc.compile.c++ bin.v2/libs/system/build/gcc-6.4.0/debug/threading-multi/error_code.o > > "/home/fabrice/buildroot/output/host/bin/arm-linux-g++" -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -Wl,-elf2flt -static -Wl,-elf2flt -static -fPIC -pthread -O0 -fno-inline -Wall -pedantic -g -DBOOST_ALL_NO_LIB=1 -DBOOST_SYSTEM_DYN_LINK=1 -I"." -c -o "bin.v2/libs/system/build/gcc-6.4.0/debug/threading-multi/error_code.o" "libs/system/src/error_code.cpp" Here, it also compiles error_code.cpp into error_code.o, which I'm not sure how it is related to the atomic stuff. > 0.084060 sec system; 0.644133 sec user; 8.858824 sec clock > SEM: gcc-link-semaphore now used by libboost_system.so.1.67.0 > Using shell: /bin/sh -c > argv[0] = '/bin/sh' > argv[1] = '-c' > argv[2] = ' > "/home/fabrice/buildroot/output/host/bin/arm-linux-g++" -o "bin.v2/libs/system/build/gcc-6.4.0/debug/threading-multi/libboost_system.so.1.67.0" -Wl,-h -Wl,libboost_system.so.1.67.0 -shared -Wl,--start-group "bin.v2/libs/system/build/gcc-6.4.0/debug/threading-multi/error_code.o" -Wl,-Bstatic -Wl,-Bdynamic -lrt -Wl,--end-group -fPIC -pthread -g -Wl,-elf2flt -static And here it tries to produce a shared library, libboost_system.so.1.67.0, which just the error_code.o object file in it ? Questions: - Why is Boost trying to _produce_ a shared library ? - How is producing a shared library from the error_code.o object file related to testing the availability of lock-free atomics ? > +# When detecting features such as lockfree atomic ints, boost does not take into > +# account the configuration provided by the user. Indeed, boost does not specify > +# any value and as a result the default value (shared) is used > +define BOOST_FIX_STATIC_FEATURES_DETECTION > +$(SED) 's/has_atomic_flag_lockfree_test.cpp/has_atomic_flag_lockfree_test.cpp : static static/g;' \ > + $(@D)/libs/thread/build/Jamfile.v2 > +endef Have you reported the issue upstream to see what they have to say ? Thanks, Thomas -- Thomas Petazzoni, CTO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com