@fsi If I understand 'free silicon' right, then you aim at a crucial but also high target. Today's silicon industry looks incredibly obscure to me. Regarding spectre, meltdown and other backdoors I used to say: 'Intel inside' -- but what's inside Intel? We'll never know and maybe they don't even know themselves 😂.
I guess you already know about HiFive? It is also open source (I never looked at the code though).
Do you plan to do something like this or are you more 'meta'?