implementing a QSYS snap-in, and the default QSYS search path

Another observation is that using a generic QSYS system with a sub-system snap-in would be more useful if we could designate QSYS exports to be conduits. For example, we have a subsystem xxxx.qsys which is used in project y and project z. In project y xxxx.qsys has different exports than in procet z. Therefore, presumably in the top level QSYS system that instantiates xxxx.qsys we will always see port connection errors unless we can designate certain exports to be conduits.

Yes, we could implement the subsystem with conduits in VHDL and use the component editor, or a manually generated QSYS script, but then we loose the ability to autoconfigure any QSYS peripherals instantiated into such subsystems into the HAL BSP using nios2-bsp. This is one of the reasons to use QSYS, of course.