SOPC Builder Warning (Tightly Coupled Memory)

I also think there is a fubar in the test within the sopc builder for these overlapped addresses.

I found that warning output whenever I put tightly coupled memory at low addresses. Trying to decode the error message led be to believe (IIRC) that the script was trying to find the low-high bounds of all the tightly coupled memory areas, but has a signed v unsigned compare error (or similar) when trying to find the low bound (I bet the range starts low=~0u, high=0 and the 'low' doesn't decrease!)

Didn't seem to stop our system working.

We have several tightly coupled memory blocks below 128k, some IO just above 128k and 16M of SDRAM at 16M.

The sopc builder won't let us alias the non-SDRAM every 256k, nor alias the IO (say each item into 256 bytes, and the whole lot every 8k).

Adding such 'don't care' bits into the address assignments would save logic and speed up the address select logic - which it what you'd do if laying out a physical board.

I even remember reading soemwhere in the Altera docs a suggestion that

you use single address bits to select logic - ie A8 high selects 'A', A9 selects 'B' etc (and both A8 and A9 high being illegal with undefined effects - possibly including the emition of 'magic smoke')