Building a dynamic library using libmaix

[pauceano]

I am trying to build a dynamic library using libmaix but I cannot.
I want to build libZMQ library,

I copied the hello_world example in libmaix, I have put al sources in main/src and includes in main/include

I have added to /libmaix/examples/libzmq/main/CMakeLists.txt
list(APPEND ADD_DEFINITIONS -fPIC)
and register_component(SHARED)
I see in the logs that compile.cmake has activated to_dynamic_lib flag.
But, after compiling everything, it ends with the following error:
.....
[ 95%] Building CXX object main/CMakeFiles/main.dir/src/zmq_utils.cpp.o
[ 96%] Building CXX object main/CMakeFiles/main.dir/src/zmtp_engine.cpp.o
[ 97%] Linking CXX shared library libmain.so
[ 97%] Built target main
Scanning dependencies of target libzmq
[ 98%] Building C object CMakeFiles/libzmq.dir/exe_src.c.o
[ 99%] Linking C executable libzmq
/opt/toolchain-sunxi-musl/toolchain/bin/../lib/gcc/arm-openwrt-linux-muslgnueabi/6.4.1/../../../../arm-openwrt-linux-muslgnueabi/lib/crt1.o: In function _start_c': /home/caiyongheng/tina/out/astar-parrot/compile_dir/toolchain/musl-1.1.16/crt/crt1.c:17: undefined reference to main'
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/libzmq.dir/build.make:89: libzmq] Error 1
make[1]: *** [CMakeFiles/Makefile2:301: CMakeFiles/libzmq.dir/all] Error 2
make: *** [Makefile:84: all] Error 2
.......
CMakeLists.txt

[Neutree]

dumplcate with #10