Determining if the pthread_create exist failed with the following output: Change Dir: /accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/build/host-grpc-v1.16.1/CMakeFiles/CMakeTmp Run Build Command:"/usr/bin/make" "cmTC_cf35a/fast" make[1]: Entering directory `/accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/build/host-grpc-v1.16.1/CMakeFiles/CMakeTmp' /usr/bin/make -f CMakeFiles/cmTC_cf35a.dir/build.make CMakeFiles/cmTC_cf35a.dir/build make[2]: Entering directory `/accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/build/host-grpc-v1.16.1/CMakeFiles/CMakeTmp' Building C object CMakeFiles/cmTC_cf35a.dir/CheckSymbolExists.c.o /usr/bin/gcc -O2 -I/accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/host/include -fPIE -o CMakeFiles/cmTC_cf35a.dir/CheckSymbolExists.c.o -c /accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/build/host-grpc-v1.16.1/CMakeFiles/CMakeTmp/CheckSymbolExists.c Linking C executable cmTC_cf35a /usr/local/bin/cmake -E cmake_link_script CMakeFiles/cmTC_cf35a.dir/link.txt --verbose=1 /usr/bin/gcc -O2 -I/accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/host/include -rdynamic CMakeFiles/cmTC_cf35a.dir/CheckSymbolExists.c.o -o cmTC_cf35a CMakeFiles/cmTC_cf35a.dir/CheckSymbolExists.c.o: In function `main': CheckSymbolExists.c:(.text.startup+0x3): undefined reference to `pthread_create' collect2: error: ld returned 1 exit status make[2]: *** [cmTC_cf35a] Error 1 make[2]: Leaving directory `/accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/build/host-grpc-v1.16.1/CMakeFiles/CMakeTmp' make[1]: *** [cmTC_cf35a/fast] Error 2 make[1]: Leaving directory `/accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/build/host-grpc-v1.16.1/CMakeFiles/CMakeTmp' File /accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/build/host-grpc-v1.16.1/CMakeFiles/CMakeTmp/CheckSymbolExists.c: /* */ #include int main(int argc, char** argv) { (void)argv; #ifndef pthread_create return ((int*)(&pthread_create))[argc]; #else (void)argc; return 0; #endif } Determining if the function pthread_create exists in the pthreads failed with the following output: Change Dir: /accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/build/host-grpc-v1.16.1/CMakeFiles/CMakeTmp Run Build Command:"/usr/bin/make" "cmTC_2446c/fast" make[1]: Entering directory `/accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/build/host-grpc-v1.16.1/CMakeFiles/CMakeTmp' /usr/bin/make -f CMakeFiles/cmTC_2446c.dir/build.make CMakeFiles/cmTC_2446c.dir/build make[2]: Entering directory `/accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/build/host-grpc-v1.16.1/CMakeFiles/CMakeTmp' Building C object CMakeFiles/cmTC_2446c.dir/CheckFunctionExists.c.o /usr/bin/gcc -O2 -I/accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/host/include -DCHECK_FUNCTION_EXISTS=pthread_create -fPIE -o CMakeFiles/cmTC_2446c.dir/CheckFunctionExists.c.o -c /usr/local/share/cmake-3.9/Modules/CheckFunctionExists.c Linking C executable cmTC_2446c /usr/local/bin/cmake -E cmake_link_script CMakeFiles/cmTC_2446c.dir/link.txt --verbose=1 /usr/bin/gcc -O2 -I/accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/host/include -DCHECK_FUNCTION_EXISTS=pthread_create -rdynamic CMakeFiles/cmTC_2446c.dir/CheckFunctionExists.c.o -o cmTC_2446c -lpthreads /usr/bin/ld: cannot find -lpthreads collect2: error: ld returned 1 exit status make[2]: *** [cmTC_2446c] Error 1 make[2]: Leaving directory `/accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/build/host-grpc-v1.16.1/CMakeFiles/CMakeTmp' make[1]: *** [cmTC_2446c/fast] Error 2 make[1]: Leaving directory `/accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-0/output/build/host-grpc-v1.16.1/CMakeFiles/CMakeTmp'