That is completely work in progress and a proof of concept. It will most likely never be included in MAME directly because of the hassle around static linking which would completely break the separation of abstraction (netlist description) and implementation. The design is that by using a hash the code looks whether a suitable solver exists in the shared library. If not, well, netlist uses the normal code. If a special solver exists - specifically for the matrix size and occupation distribution - it will take it from the shared library. Easy as that - if we don't have it you won't get it. But it's completely optional and proof of concept.