I am building a dll from assembly on Windows using the GNU binutils.
I know that the dll can be either loaded when the executable is loaded or at run-time (using the LoadLibrary api call).
For load-time loading, I seem to be only needing the dll file : no .a, .lib or .def file is needed. I wondered what these file format represent and what purpose do they serve.
What I know and some specific questions :
.a is the extension generally used for static library on Unix. .a files are generated with the –out-implib option of GNU ld. It is said to be an "import library", fair enough. The question is then "What good is an import library to me if I don't need it when linking ?"
.lib is the extension used for static library on Windows, and according to wikipedia, is also used as "import library" under windows, so I strongly suspect they're just another name for what the binutils call .a files. True/false ?
All pages I can find points that .def files list the exported symbol of the dll. Isn't that somewhat similar to what an "import library" is supposed to do ?
Also, I read here that using .def files is an alternative to manually specifying exports in the source file (which I did). But I also remember reading (cannot find reference back) .def file supply an index (ordinal) into the exported symbols, allowing for faster run-time loading. Is that so ?