However, I assume any chip released after they added the backdoors also has the backdoors. So, you'd be looking for pre-2007, Pentium-class chips in SMP configuration. Maybe Pentium 4 Prescot-2M or Cedar Mill. Wikipedia shows the latter was on same node as Core Duo with 3-3.6GHz plus 2MB cache.
Far as non-Intel, both PPC and SPARC used Open Firmware. Plenty of them on eBay. Gaisler also made GPL versions of Leon3 you could build yourself or buy as a development board for who knows what price.
In high-assurance security, I remember BootSafe tech letting someone write firmware in Java to benefit from all its testing and verification tech that was then translated into Open Firmware's Forth in a way that preserved the properties. That tech went proprietary but still exists. Something similar could be done in FOSS with a Rust or SPARK to Forth converter leveraging hard work already done by compiler/verification teams of source languages.
https://minifree.org/product/libreboot-t400/
However, I assume any chip released after they added the backdoors also has the backdoors. So, you'd be looking for pre-2007, Pentium-class chips in SMP configuration. Maybe Pentium 4 Prescot-2M or Cedar Mill. Wikipedia shows the latter was on same node as Core Duo with 3-3.6GHz plus 2MB cache.
Far as non-Intel, both PPC and SPARC used Open Firmware. Plenty of them on eBay. Gaisler also made GPL versions of Leon3 you could build yourself or buy as a development board for who knows what price.
https://en.wikipedia.org/wiki/Open_Firmware
In high-assurance security, I remember BootSafe tech letting someone write firmware in Java to benefit from all its testing and verification tech that was then translated into Open Firmware's Forth in a way that preserved the properties. That tech went proprietary but still exists. Something similar could be done in FOSS with a Rust or SPARK to Forth converter leveraging hard work already done by compiler/verification teams of source languages.
http://www.cs.cornell.edu/~kozen/papers/acsac.pdf