So what's state-of-the-art in open-source ?

Is where it's at? I'm interested in synthesizing cpu cores which I think puts me in the area of large-ish fabric devices but again I stopped looking for a few months and now I feel like I have no idea what to expect :)

@vertigo @h @cstanhope

@jjg @h @cstanhope reverse engineering work with Xilinx artix 7 is ongoing. Otherwise, the state-of-the-art is the Yosys tool chain for the iCE40HX family.

@jjg @h @cstanhope ISTR there was a recent announcement at a recent C3 convention to this effect, but I am not fully aware of what that announcement was about. Might want to check up the itinerary and videos from the latest C3 conference.

@vertigo I'm still not clear what's the situation regarding RISC-V and FPGA development, what's at the intersection of these two important building blocks. @jjg @cstanhope

@h @jjg @cstanhope Can you be more specific?

Right now, the "official" RISC-V reference implementation, Rocket, is still ASIC-optimized. FPGA-based RISC-V cores tend to be home-grown things these days.

You can still synthesize Rocket on an FPGA, but because it's optimized for ASICs, it needs a rather large FPGA to do so, since it's investing individual LUTs to things that can be only a few transistors in an ASIC.

@vertigo What I mean is that the current state of affairs makes every industrially-made CPU suspectful. Especially those made in countries with governments known for spying on citizens wholesale, who attempted to build the Clipper chip in the past.
I'm wondering how far we can go building these systems really from scratch. We still depend on Xilinx or Altera/Intel at some point anyway.
I'm curious about your point of view on these matters.

@jjg @cstanhope

@h @cstanhope @jjg @vertigo It's difficult because as far as I know producing CPUs at anything like a sane price point still requires a serious amount of capital. With major efforts it can be possible to make individual transistors, like Jeri Ellsworth did with a hacked microwave, but I don't think it would be possible to reliably make CPUs that way.

@bob @jjg @cstanhope @h Wasn't there someone looking to make 10um or 8um feature-sized semiconductors using garage-accessible equipment not long ago? If so, and once you're familiar with the characteristics of the transistors at those sizes, you can definitely at least make a Z80 or 6502 equivalent CPU.

@h @cstanhope @jjg @bob You can also make a TTA engine to emulate a larger CPU as well; e.g., a 68000 or RISC-V processor could easily be made this way, but you'll pay in clock cycles.

@vertigo @jjg @cstanhope @h There's also the Qubes approach of layering virtual machines on top of hardware which is known to probably be bad. The idea being that even if data can be exfiltraded all the adversary gets is cyphertext. But I'm not entirely convinced that this is a viable way to go.

@bob @h @cstanhope @jjg That certainly will never fly in production environments. The computing power necessary to reduce signal-to-noise ratio for side-channels takes away from what you'd invest normally in servicing production traffic.

@vertigo @bob @h @cstanhope fun thread :)

My motivation is threefold:

1. Learn how to actually build stuff with FPGA and start with open tools of at all possible
2. Design a module for RAIN that can be used to provide application-specific logic, acceleration and other experimental stuff along side the traditional processor modules


3. I’ve been noodling on the idea of a fully-dynamic hardware parallel machine for awhile and curious how possible it might be to realize that using contemporary commodity hardware

@cstanhope @bob @vertigo

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