[gmx-users] resolution of cygwin installation issues

[Mark Abraham]

Hi,

After all the recent trouble with people attempting to install on Cygwin 
with autoconf, I went and tried it myself. I knew GROMACS 4.5.5 built 
with CMake on Cygwin.

It turns out the default installation of FFTW uses static libraries, and 
with the default configuration of GROMACS the linker has trouble with 
that. In the very long make output of GROMACS it warns

*** Warning: This system can not link to static lib archive 
/usr/local/lib/libfftw3f.la.
*** I have the capability to make that library automatically link in when
*** you link to this library.  But I can only do this if you have a
*** shared version of the library, which you do not appear to have.

before going on to report failure to link to a bunch of symbols in the 
FFTW library. If those who'd been having trouble had reported this, then 
they'd have had a quicker solution :)

With default FFTW installed in the default location (/usr/local, 
configured with "./configure --enable-sse --enable-float"), I succeeded 
in building GROMACS on a new installation of Cygwin with

./configure --disable-threads CPPFLAGS=-I/usr/local/include 
LDFLAGS=-L/usr/local/lib --enable-all-static --without-xml
make

I experimented a bit with trying to get shared libraries to work, but 
didn't succeed. Too bad. I have updated 
http://www.gromacs.org/Documentation/Installation_Instructions/Cygwin_HOWTO. 
Hope this is useful.

Mark