[simias]

And event then you have to trust the closed source synthesis tools on top of the FPGA itself... Of course it would be harder to backdoor but it's probably doable, especially if it targets those particular designs specifically.

There's simply no way to get a completely trusted computer stack nowadays, short of assembling it by hand using discrete electronics. It won't run very fast though...

I guess an alternative would be to crowdfund the production of an open source CPU then take a few samples and send them to people with an electron microscope and a lot of patience to make sure that the silicon really matches the design and wasn't tempered with in the fab.