CMake can't find threads with Linaro toolchain - cmake

Question

I can't get CMake to find threads with a Linaro ARM toolchain (I've tried several different ones). Here's what I've done:
Downloaded the gcc-linaro-4.9-2015.05-x86_64_arm-linux-gnueabihf.tar.xz toolchain and extracted to /opt.
Downloaded the corresponding sysroot and extracted to ~/sysroot
I created a Toolchain-Linaro-arm.cmake file that looks like this:
set (CMAKE_SYSTEM_NAME Linux)
include (CMakeForceCompiler)
set (TOOLCHAIN_BASE "/opt/gcc-linaro-4.9-2015.05-x86_64_arm-linux-gnueabihf/")
set (CMAKE_SYSTEM_PROCESSOR armhf-cortexa9)
CMAKE_FORCE_C_COMPILER("${TOOLCHAIN_BASE}/bin/arm-linux-gnueabihf-gcc" GNU)
CMAKE_FORCE_CXX_COMPILER("${TOOLCHAIN_BASE}/bin/arm-linux-gnueabihf-g++" GNU)
set (CMAKE_FIND_ROOT_PATH ${CMAKE_FIND_ROOT_PATH} /home/user/sysroot)
set (CMAKE_SIZEOF_VOID_P 4)
set (CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set (CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set (CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
set (CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
I created a minimal example project that uses threads:
~/threadstest $ ls
CMakeLists.txt main.cpp
~/threadstest $ cat CMakeLists.txt
cmake_minimum_required(VERSION 3.0.0)
project(threads_test)
add_executable(test main.cpp)
find_package(Threads REQUIRED)
target_link_libraries(test, ${CMAKE_THREAD_LIBS_INIT})
~/threadstest $ cat main.cpp
int main() { }
~/threadstest $ mkdir build; cd build
~/threadstest/build $ cmake -DCMAKE_TOOLCHAIN_FILE=~/Toolchain-Linaro-arm.cmake ..
CMake Error at /opt/cmake-3.3.1-Linux-x86_64/share/cmake-3.3/Modules/FindPackageHandleStandardArgs.cmake:148 (message):
Could NOT find Threads (missing: Threads_FOUND)
Call Stack (most recent call first):
/opt/cmake-3.3.1-Linux-x86_64/share/cmake-3.3/Modules/FindPackageHandleStandardArgs.cmake:388 (_FPHSA_FAILURE_MESSAGE)
/opt/cmake-3.3.1-Linux-x86_64/share/cmake-3.3/Modules/FindThreads.cmake:205 (FIND_PACKAGE_HANDLE_STANDARD_ARGS)
CMakeLists.txt:8 (find_package)
~/threadstest/build $ cat CMakeFiles/CMakeError.log
Determining if files pthread.h exist failed with the following output:
Change Dir: /home/user/threadstest/arm/CMakeFiles/CMakeTmp
Run Build Command:"/usr/bin/make" "cmTC_37a3c/fast"
/usr/bin/make -f CMakeFiles/cmTC_37a3c.dir/build.make CMakeFiles/cmTC_37a3c.dir/build
make[1]: Entering directory `/home/user/threadstest/arm/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_37a3c.dir/CheckIncludeFiles.c.o
/opt/gcc-linaro-4.9-2015.05-x86_64_arm-linux-gnueabihf//bin/arm-linux-gnueabihf-gcc -o CMakeFiles/cmTC_37a3c.dir/CheckIncludeFiles.c.o -c /home/user/threadstest/arm/CMakeFiles/CMakeTmp/CheckIncludeFiles.c
/opt/gcc-linaro-4.9-2015.05-x86_64_arm-linux-gnueabihf//bin/arm-linux-gnueabihf-gcc: /lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.14' not found (required by /opt/gcc-linaro-4.9-2015.05-x86_64_arm-linux-gnueabihf//bin/arm-linux-gnueabihf-gcc)
make[1]: Leaving directory `/home/user/threadstest/arm/CMakeFiles/CMakeTmp'
make[1]: *** [CMakeFiles/cmTC_37a3c.dir/CheckIncludeFiles.c.o] Error 1
make: *** [cmTC_37a3c/fast] Error 2
Source:
/* */
#include <pthread.h>
int main(void){return 0;}
I know the pthread libraries exist:
$ find ~/sysroot -name "*pthread*"
/home/user/sysroot/usr/lib/libpthread_nonshared.a
/home/user/sysroot/usr/lib/libpthread.so.0
/home/user/sysroot/usr/lib/libpthread-2.19-2014.08-1-git.so
/home/user/sysroot/usr/lib/libpthread_p.a
/home/user/sysroot/usr/lib/libpthread.a
/home/user/sysroot/usr/lib/libpthread.so
/home/user/sysroot/usr/include/bits/pthreadtypes.h
/home/user/sysroot/usr/include/pthread.h
It looks like something is still looking at my native libc and not the cross compiling environment:
/opt/gcc-linaro-4.9-2015.05-x86_64_arm-linux-gnueabihf//bin/arm-linux-gnueabihf-gcc -o CMakeFiles/cmTC_37a3c.dir/CheckIncludeFiles.c.o -c /home/user/threadstest/arm/CMakeFiles/CMakeTmp/CheckIncludeFiles.c
/opt/gcc-linaro-4.9-2015.05-x86_64_arm-linux-gnueabihf//bin/arm-linux-gnueabihf-gcc: /lib/x86_64-linux-gnu/libc.so.6: version "GLIBC_2.14" not found (required by /opt/gcc-linaro-4.9-2015.05-x86_64_arm-linux-gnueabihf//bin/arm-linux-gnueabihf-gcc)

Answer 1

The root cause of the problem not in pthread library:
The root cause is:
/lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.14' not found (required by /opt/gcc-linaro-4.9-2015.05-x86_64_arm-linux-gnueabihf//bin/arm-linux-gnueabihf-gcc)
Your compiler is trying to use your local libc.
1) Find libc.so* in downloaded sysroot and check version with the following command:
objdump -p libc.so.6 | grep "Version References:" -A 10
The if everything is ok use this lib (with --sysroot options);
You may try to do it manually:
/opt/gcc-linaro-4.9-2015.05-x86_64_arm-linux-gnueabihf//bin/arm-linux-gnueabihf-gcc -o CMakeFiles/cmTC_37a3c.dir/CheckIncludeFiles.c.o -c /home/user/threadstest/arm/CMakeFiles/CMakeTmp/CheckIncludeFiles.c --sysroot /home/user/sysroot/
2) Your toolchains probably compiled with differ libc.so version than installed on your system, download appropriate version on your system and use it.