Hi, On Sun, 2017-02-05 at 23:03 +0100, Jörg Krause wrote: > Hi, > > when using CHECK_{SYMBOL,FUNCTION}_EXISTS in a cross-compilation > environment, CMake passes the host rpath to the linker: > > """ CMakeOutput.log > > /home/joerg/host/usr/bin/i586-linux-gcc > --sysroot=/home/joerg/host/usr/i586-buildroot-linux-musl/sysroot > -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 > -Os -DNDEBUG CMakeFiles/cmTC_cb8f6.dir/CheckSymbolExists.c.o -o > cmTC_cb8f6 -Wl,-rpath,/usr/lib32 -rdynamic /home/joerg/host/usr/i586- > buildroot-linux-musl/sysroot/usr/lib32/libmbedtls.so > /home/joerg/host/usr/i586-buildroot-linux- > musl/sysroot/usr/lib32/libmbedx509.so /home/joerg/host/usr/i586- > buildroot-linux-musl/sysroot/usr/lib32/libmbedcrypto.so > > """ > > This leads to a linker error if mbedtls is linked with zlib, as the > linker tries to link with the host zlib and does not find the host > libc: > > """ CMakeError.txt > > /home/joerg/host/usr/i586-buildroot-linux-musl/bin/ld: warning: > libc.so.6, needed by /usr/lib32/libz.so.1, not found (try using > -rpath > or -rpath-link) > /usr/lib32/libz.so.1: undefined reference to `strcpy@GLIBC_2.0' > /usr/lib32/libz.so.1: undefined reference to `free@GLIBC_2.0' > /usr/lib32/libz.so.1: undefined reference to `fseeko64@GLIBC_2.1 > [..] > > """ > > I did not find any solution which allows me to remove the rpath from > the check. Setting CMAKE_SKIP_RPATH does not change the build > behaviour of the check_symbol_exists macro. > > From my understanding, the rpath flag should not be used when the > sysroot flag is passed to the linker, right? > > For reference, I added a minimal example which uses Buildroot for > cross-compilation. > > """ CMakeLists.txt > > cmake_minimum_required(VERSION 2.8.12) > > project(test) > > list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake") > > find_package(MbedTLS) > if(MBEDTLS_FOUND) > message(STATUS "Using mbedTLS") > endif() > > """ > > """ FindMbedTLS.cmake > > include(CheckSymbolExists) > > find_path(MBEDTLS_INCLUDE_DIRS > NAMES mbedtls/ssl.h > PATH_SUFFIXES include > ) > > find_library(MBEDTLS_LIBRARY NAMES mbedtls) > find_library(MBEDX509_LIBRARY NAMES mbedx509) > find_library(MBEDCRYPTO_LIBRARY NAMES mbedcrypto) > > if(MBEDTLS_LIBRARY AND MBEDX509_LIBRARY AND MBEDCRYPTO_LIBRARY) > set(CMAKE_REQUIRED_INCLUDES ${MBEDTLS_INCLUDE_DIRS}) > set(CMAKE_REQUIRED_LIBRARIES ${MBEDTLS_LIBRARY} > ${MBEDX509_LIBRARY} ${MBEDCRYPTO_LIBRARY}) > check_symbol_exists(mbedtls_ssl_init "mbedtls/ssl.h" > MBEDTLS_V2) > endif() > > """ > > """ toolchainfile.cmake > > string(REPLACE "/usr/share/buildroot" "" RELOCATED_HOST_DIR > ${CMAKE_CURRENT_LIST_DIR}) > > set(CMAKE_SYSTEM_NAME Linux) > set(CMAKE_SYSTEM_PROCESSOR i586) > > set(CMAKE_C_FLAGS_DEBUG "" CACHE STRING "Debug CFLAGS") > set(CMAKE_CXX_FLAGS_DEBUG "" CACHE STRING "Debug CXXFLAGS") > set(CMAKE_C_FLAGS_RELEASE " -DNDEBUG" CACHE STRING "Release CFLAGS") > set(CMAKE_CXX_FLAGS_RELEASE " -DNDEBUG" CACHE STRING "Release > CXXFLAGS") > > # Build type from the Buildroot configuration > set(CMAKE_BUILD_TYPE Release CACHE STRING "Buildroot build > configuration") > > # Buildroot defaults flags. > set(CMAKE_C_FLAGS "-D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE > -D_FILE_OFFSET_BITS=64 -Os" CACHE STRING "Buildroot CFLAGS") > set(CMAKE_CXX_FLAGS "-D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE > -D_FILE_OFFSET_BITS=64 -Os" CACHE STRING "Buildroot CXXFLAGS") > set(CMAKE_EXE_LINKER_FLAGS "" CACHE STRING "Buildroot LDFLAGS for > executables") > > set(CMAKE_INSTALL_SO_NO_EXE 0) > > set(CMAKE_PROGRAM_PATH "${RELOCATED_HOST_DIR}/usr/bin") > set(CMAKE_SYSROOT "${RELOCATED_HOST_DIR}/usr/i586-buildroot-linux- > musl/sysroot") > set(CMAKE_FIND_ROOT_PATH "${RELOCATED_HOST_DIR}/usr/i586-buildroot- > linux-musl/sysroot") > set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER) > set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY) > set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY) > set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY) > set(ENV{PKG_CONFIG_SYSROOT_DIR} "${RELOCATED_HOST_DIR}/usr/i586- > buildroot-linux-musl/sysroot") > > # This toolchain file can be used both inside and outside Buildroot. > set(CMAKE_C_COMPILER "${RELOCATED_HOST_DIR}/usr/bin/i586-linux-gcc") > set(CMAKE_CXX_COMPILER "${RELOCATED_HOST_DIR}/usr/bin/i586-linux- > g++") > > """ > > What do I miss?
Note, that this project was build using CMake 3.7.2 on Debian. When using CMake 3.6.3, CMake does correctly not add rpath to the cross- linker and the check_symbol_exists() succeeds. Jörg -- Powered by www.kitware.com Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ Kitware offers various services to support the CMake community. For more information on each offering, please visit: CMake Support: http://cmake.org/cmake/help/support.html CMake Consulting: http://cmake.org/cmake/help/consulting.html CMake Training Courses: http://cmake.org/cmake/help/training.html Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Follow this link to subscribe/unsubscribe: http://public.kitware.com/mailman/listinfo/cmake