[bcantrill]

This is a very reasonable inference, as it absolutely was when I gave that talk. ;) Very shortly after that talk, however, we came to the realization that the OpenTitan was not going to be what we needed when we needed it, and moved to a Cortex M7-based microcontroller for our service processor (and a separate M33-based microcontroller for our root of trust); Hubris is the operating system that runs on those two MCUs.

[panick21_]

Not that it matters all that much, but why a Cortex when you can get RISC-V chips form SiFive (or whoever) that do about the same stuff?

Does that mean the product will not have an FPGA? I kind of liked that idea of updating the hardware.

P.S: Twitter spaces about the history of computing are really fun. Love to hear more about all the dead computer companies you researched. There is not enough content about computer history out there.

[bcantrill]

Yeah... a bunch of reasons. We definitely have a couple of FPGAs in the product (Bluespec FTW!), and we anticipate that we will have more over time -- but not for the RoT or SP, or at least not now. The reasons are different for each, but include:

1. ASICs are out of the question for us for a bunch of economic reasons

2. FPGAs by and large do not have a good security story

3. The ones that do (or rather, the one that does) has an entirely proprietary ecosystem and a terrible toolchain -- and seems to rely on security-through-obscurity

4. Once you are away from a softcore, the instruction set is frankly less material than the SoC -- and the RISC-V SoC space is still immature in lots of little ways relative to the Cortex space

5. Frankly, there's a lot to like about ST: good parts, good docs, good eval boards, pretty good availability (!), minimum of proprietary garbage.

We tried really hard (and indeed, I think my colleagues would say that I probably tried a little too hard) to get FPGAs to be viable, and then to get FPGAs + hardcores to be viable, and then multicore hardcores to be viable (one for the SP, one for the RoT). Ultimately, all of these paths proved to be not yet ready. And while we're big believers in FPGAs and RISC-V, we're even bigger believers in our need to ship a product! ;)

[bcantrill]

Also, where are my manners?! Really glad you're enjoying our Twitter Spaces[0] -- and thank you for the kind words!

[0] https://github.com/oxidecomputer/twitter-spaces