Determining if the __x86_64__ exist failed with the following output: Change Dir: /tmp/instance-0/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/CMakeFiles/CMakeTmp Run Build Command(s):/usr/bin/make cmTC_ef8b5/fast && make[1]: Entering directory '/tmp/instance-0/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/CMakeFiles/CMakeTmp' /usr/bin/make -f CMakeFiles/cmTC_ef8b5.dir/build.make CMakeFiles/cmTC_ef8b5.dir/build make[2]: Entering directory '/tmp/instance-0/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/CMakeFiles/CMakeTmp' Building C object CMakeFiles/cmTC_ef8b5.dir/CheckSymbolExists.c.o /tmp/instance-0/output-1/host/bin/arm-buildroot-linux-gnueabihf-gcc --sysroot=/tmp/instance-0/output-1/host/arm-buildroot-linux-gnueabihf/sysroot -D_POSIX_C_SOURCE=200112L -fPIC -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -g0 -D_FORTIFY_SOURCE=1 -Werror -Werror -DNDEBUG -fPIE -o CMakeFiles/cmTC_ef8b5.dir/CheckSymbolExists.c.o -c /tmp/instance-0/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/CMakeFiles/CMakeTmp/CheckSymbolExists.c /tmp/instance-0/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/CMakeFiles/CMakeTmp/CheckSymbolExists.c: In function 'main': /tmp/instance-0/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/CMakeFiles/CMakeTmp/CheckSymbolExists.c:7:19: error: '__x86_64__' undeclared (first use in this function) 7 | return ((int*)(&__x86_64__))[argc]; | ^~~~~~~~~~ /tmp/instance-0/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/CMakeFiles/CMakeTmp/CheckSymbolExists.c:7:19: note: each undeclared identifier is reported only once for each function it appears in make[2]: *** [CMakeFiles/cmTC_ef8b5.dir/build.make:69: CMakeFiles/cmTC_ef8b5.dir/CheckSymbolExists.c.o] Error 1 make[2]: Leaving directory '/tmp/instance-0/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/CMakeFiles/CMakeTmp' make[1]: *** [Makefile:124: cmTC_ef8b5/fast] Error 2 make[1]: Leaving directory '/tmp/instance-0/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/CMakeFiles/CMakeTmp' File /tmp/instance-0/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/CMakeFiles/CMakeTmp/CheckSymbolExists.c: /* */ int main(int argc, char** argv) { (void)argv; #ifndef __x86_64__ return ((int*)(&__x86_64__))[argc]; #else (void)argc; return 0; #endif } Determining if the __i386__ exist failed with the following output: Change Dir: /tmp/instance-0/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/CMakeFiles/CMakeTmp Run Build Command(s):/usr/bin/make cmTC_055bf/fast && make[1]: Entering directory '/tmp/instance-0/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/CMakeFiles/CMakeTmp' /usr/bin/make -f CMakeFiles/cmTC_055bf.dir/build.make CMakeFiles/cmTC_055bf.dir/build make[2]: Entering directory '/tmp/instance-0/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/CMakeFiles/CMakeTmp' Building C object CMakeFiles/cmTC_055bf.dir/CheckSymbolExists.c.o /tmp/instance-0/output-1/host/bin/arm-buildroot-linux-gnueabihf-gcc --sysroot=/tmp/instance-0/output-1/host/arm-buildroot-linux-gnueabihf/sysroot -D_POSIX_C_SOURCE=200112L -fPIC -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os -g0 -D_FORTIFY_SOURCE=1 -Werror -Werror -DNDEBUG -fPIE -o CMakeFiles/cmTC_055bf.dir/CheckSymbolExists.c.o -c /tmp/instance-0/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/CMakeFiles/CMakeTmp/CheckSymbolExists.c /tmp/instance-0/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/CMakeFiles/CMakeTmp/CheckSymbolExists.c: In function 'main': /tmp/instance-0/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/CMakeFiles/CMakeTmp/CheckSymbolExists.c:7:19: error: '__i386__' undeclared (first use in this function) 7 | return ((int*)(&__i386__))[argc]; | ^~~~~~~~ /tmp/instance-0/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/CMakeFiles/CMakeTmp/CheckSymbolExists.c:7:19: note: each undeclared identifier is reported only once for each function it appears in make[2]: *** [CMakeFiles/cmTC_055bf.dir/build.make:69: CMakeFiles/cmTC_055bf.dir/CheckSymbolExists.c.o] Error 1 make[2]: Leaving directory '/tmp/instance-0/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/CMakeFiles/CMakeTmp' make[1]: *** [Makefile:124: cmTC_055bf/fast] Error 2 make[1]: Leaving directory '/tmp/instance-0/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/CMakeFiles/CMakeTmp' File /tmp/instance-0/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/CMakeFiles/CMakeTmp/CheckSymbolExists.c: /* */ int main(int argc, char** argv) { (void)argv; #ifndef __i386__ return ((int*)(&__i386__))[argc]; #else (void)argc; return 0; #endif }