building DLLs (was:RE: New user help - dont understand Mount (and the rest))

Charles Wilson cwilson@ece.gatech.edu
Wed Feb 21 07:47:00 GMT 2001


Markus Hoenicka wrote:

> 
> This is similar to what I tried before, but I still get:
> Cannot export _bss_end__: symbol not defined
> Cannot export _bss_start__: symbol not defined
> Cannot export _data_end__: symbol not defined
> Cannot export _data_start__: symbol not defined
> Creating library file: libosp.dll.a
> collect2: ld returned 1 exit status
> 
> Unfortunately I lack a basic understanding of DLLs. What do these
> messages mean to me? Am I supposed to provide definitions for those
> symbols or am I supposed to remove some definitions that make the
> symbols show up in the exports?

The latter.  _bss_end & friends should not really be exported.

> 
> I'd like to add that the DLL-to-be that I'm fiddling with
> (libosp.dll/OpenSP) builds on Win32/MSVC and Linux etc, so I assume
> that the code is prepared for building a DLL. The __declspec() magic
> is included via #define.

building DLL's from C++ is not as well-studied as C.  Take a look at the
makefile in the <TOP>/ncurses/c++/ directory from the
ncurses-5.2-4-src.tar.gz tarball on any cygwin mirror for a clue.  Or,
for a smaller download, look at 

http://www.neuro.gatech.edu/users/cwilson/cygutils/dllhelpers-0.2.6.tar.gz

which is based on Mumit's original 0.2.5 version.

Unfortunately, I've got a deadline or I'd address this question a little
more thoroughly.  I'll try to get back to it this weekend.

--Chuck

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