I've been playing with building a MinGW perl using cygwin (see my notes at http://perlmonks.org/?node=419122) having never built a (non-cygwin) win32 perl before, and am getting test failures in lib/Config/Extensions.t. It looks like win32 does a very poor job of setting the extentions/*_ext fields in config.sh, so I would expect regular win32 builds to also be seeing this problem. I've started to look at fixing it, and should have a patch in the next 12 hours or so, unless someone beats me to it. One question I had was that for platforms using Configure, known_extensions doesn't include nonxs extensions or DynaLoader (whereas for win32 it is just a copy of extensions, so includes nonxs ones). Should nonxs extensions be listed? Should DynaLoader? Should extensions include DynaLoader? (It doesn't now on win32 or via Configure AFAICT.)