The eCos configuration and building process (described in Getting Started with eCos and eCos User's Guide) builds a single library, libtarget.a, which contains the selected eCos components. The libtarget.a library does not contain any user libraries: If you put some of your source in libraries, you will have to explicitly include those libraries in the linking instruction.
You also need to link to the GNU C Compiler runtime support library (libgcc.a).
You should not link to the standard C++ library. This can be achieved with the -nostdlib option.
You should only link to libtarget.a and libgcc.a using the linker script target.ld provided with eCos. The command line for linking should look like
gcc [options] [object files] -Ttarget.ld -nostdlib |