>From my perspective as a maintainer of the reference implementation of NTP, I value make portability and would be disappointed to see Automake become GNU-make-specific. We strive to make our tarballs easy to build and install on a wide variety of new and old systems. As an example, until a little over a year ago when NTP 4.2.6 was released, our stable release supported K&R C compilers. Requiring GNU make would reduce the portability of NTP, unless we were to bundle GNU make source and build it when needed, which is likely not an option for us as our project has a BSD-derived license.
Cheers, Dave Hart
