diff -uprN -x build -x comp_sql cJSON_orig/CMakeLists.txt cJSON/CMakeLists.txt
--- cJSON_orig/CMakeLists.txt	2019-08-28 11:06:20.851852257 +0800
+++ cJSON/CMakeLists.txt	2019-08-28 11:06:52.346617001 +0800
@@ -12,6 +12,33 @@ set(CJSON_VERSION_SO 1)
 set(CJSON_UTILS_VERSION_SO 1)
 set(PROJECT_VERSION "${PROJECT_VERSION_MAJOR}.${PROJECT_VERSION_MINOR}.${PROJECT_VERSION_PATCH}")
 
+if(PLAT_ARM64)
+    # this one is important
+    SET(CMAKE_SYSTEM_NAME Linux)
+    #this one not so much
+    SET(CMAKE_SYSTEM_VERSION 1)
+    # this is install root directory
+    SET(CMAKE_INSTALL_PREFIX /usr)
+
+    # specify the cross compiler
+    SET(CMAKE_C_COMPILER   aarch64-linux-gnu-gcc)
+    SET(CMAKE_CXX_COMPILER aarch64-linux-gnu-g++)
+    SET(CMAKE_STRIP aarch64-linux-gnu-strip)
+
+    # specify the cross compile and link flags
+    set(CMAKE_C_FLAGS "--sysroot=$ENV{SDKTARGETSYSROOT}")
+    set(CMAKE_SHARED_LINKER_FLAGS "--sysroot=$ENV{SDKTARGETSYSROOT}")
+    SET(CMAKE_LIBRARY_PATH $ENV{SDKTARGETSYSROOT}/usr/lib)
+
+    # where is the target environment
+    SET(CMAKE_FIND_ROOT_PATH  ${SDKTARGETSYSROOT})
+
+    # search for programs in the build host directories
+    SET(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+    # for libraries and headers in the target directories
+    SET(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+    SET(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+endif()
 
 set(custom_compiler_flags)