Reini Urban wrote: > Where do I define the win64 style unwinder for cygwin 64bit? I guess one needs to select the Windows variants for memory management (lj_alloc.c, lj_mcode.c) and error handling (lj_err.c). Look for LJ_TARGET_WINDOWS in lj_alloc.c and lj_mcode.c. And for the last two occurences of LJ_TARGET_WINDOWS in lj_err.c. You'll need a GCC that uses native WIN64 exceptions. Once the build is ok, check that error handling works and prints a backtrace: luajit -e "error('test')" --Mike