Which platforms are fully supported will ultimately depend on the needs of the community, as expressed by the participation in developing, and testing for each platform?
The core plugins are written in Java with no native code and thus may be ported to any platform supported by Eclipse. However, some default implementations may require that other software or tools, licensed under GNU, may be required. In general there is some version of Linux and some version of windows used by the developers on the CDT. For an exact list of supported platforms see the Downloads page.