From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Petazzoni Date: Thu, 6 Sep 2018 21:05:45 +0200 Subject: [Buildroot] [PATCH v3, 1/1] boost: fix static detection of lock-free atomic ints In-Reply-To: <20180905105127.31591-1-fontaine.fabrice@gmail.com> References: <20180905105127.31591-1-fontaine.fabrice@gmail.com> Message-ID: <20180906210545.6717e9ac@windsurf> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net Hello Fabrice, Thanks again for your work on this topic. However, I am sorry, but I still don't understand :-/ On Wed, 5 Sep 2018 12:51:27 +0200, Fabrice Fontaine wrote: > +When build statically, boost is unable to detect lock-free atomics ints > +because it tries to link dynamically with boost_system, see I don't see where it tries to link dynamically with boost_system. > +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" Here it builds the object file has_atomic_flag_lockfree_test.o, it uses -static, there's no -shared or nothing really wrong here. This tests succeeds, so lock-free atomic ints are available, we're all good. It does *not* try to link against libboost_system 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" > + > +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 Here is also does not try to link against libboost_system: it tries to *generate* it! The summarized command is "g++ -o libboost_system.so.1.67.0" so the overall goal of the command is to *produce* libboost_system.so.1.67.0, not to link against it. > +ld (ld-elf2flt): -shared used without passing a shared library ID Obviously, this fails because building shared libraries is not possible in this static-only configuration. But I fail to see the relation: - Between producing libboost_system.so and the "project boost/thread" thing - Between inverting "project boost/thread" and the atomic_flag_lock_free test and this issue disappearing. This still feel very mysterious to me. Best regards, Thomas -- Thomas Petazzoni, CTO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com