OSDev.org

Both newlib and libstdc++ ignore the "--enable-shared" flag as the target "arm-none-eabi" doesn't support shared libraries in the configuration script. In the case for a custom operating system and you want to add shared library support that makes it a little bit unfortunate. Have anyone successfully compiled newlib and libstdc++ so that it outputs .so shared libraries for ARM custom OS targets?

You need to set up an OS-specific toolchain. If you got a working user-space, it's a time time to invest in setting up such a toolchain. You can then adapt it nicely for whatever needs you have.