Make sure you open-source the compiler, the firmware, the hardware manufacturing process, the assembly, the drivers, the software that built the compiler, and the software that built the compiler that built the compiler.
Or just operate under the assumption that some of the machines are compromised and make sure you have ways of recognizing faults after-the-fact.
You say this in a way that implies that it's not feasible to do such a thing. I'm pretty sure that all of those components have been open sourced in various projects, just maybe not all in the same system.
Or just operate under the assumption that some of the machines are compromised and make sure you have ways of recognizing faults after-the-fact.