You must use the --apcs /interwork command-line option to compile any C or C++ modules that contain functions that might return to the other instruction set.

You must use the --apcs /interwork command-line option to compile any C or C++ modules that contain indirect or virtual function calls that might be to functions in the other instruction set.

Never make indirect calls, such as calls using function pointers, to non-interworking code from code in the other state.

If any input object contains Thumb code, the linker selects the Thumb runtime libraries. These are built for interworking.

If you specify one of your own libraries explicitly on the linker command line you must ensure that it is an appropriate interworking library.