riscv_vhdl VS VexRiscv

There is code that describes the processor, the VHDL is also open source. You can get the some similar implementations for older ARM implementations but you may have to pay to use them commercially.

It looks like the baochip-1x is using the VexRiscv CPU. The HDL is available here under MIT: https://github.com/SpinalHDL/VexRiscv

With LiteX you can synthesize a VexRiscV processor. You can run Linux on it. The toolchain is pretty easy to use, as long as you use Xilinx Vivado to compile to gateware.

I don't get what's going on with licensing and device support. I'm missing something here perhaps, but we use Cyclone 10 GX onwards and Quartus Pro so I don't have enough context maybe. Have you considered swapping your Nios ii to a VexRISCV as a side note? At ~1 Dhrystone MIPS/MHz it's roughly double that of the Nios V, for very few resources. All open source too. None of the migration documentation support though, so I can't judge how hard it would be.

If you use LiteX to generate a VexRiscV system-on-a-chip, you can include an open source DDR DRAM PHY. This works on Xilinx Spartan-6, Spartan7Artix7/Kintex7/Virtex7 FPGAs, and Lattice ECP5 FPGAs. DDR/LPDDR/DDR2/DDR3 depending on the FPGA.

Something like https://github.com/SpinalHDL/VexRiscv will take far fewer

A CPU built around the Gentoo philosophy would look like https://github.com/SpinalHDL/VexRiscv ;). Don't want an MMU? Fine. Need a larger RAM interface? You got it. Barrel ALU for DSP? Sure.

Interpreted languages work by consolidating all of the optimization effort in the interpreter. This is similar to how CPUs work now, instead of extremely specific optimizations that are hard to create distributed among all code we use very general optimizations that push the limits of mathematics that is centralized in a CPU.

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Itanium had a lot of contemporary issues that made it not work. I would certainly blame Intel's business practices and reputation for a large part of it. There are likely niches for such processors. The VLIW is useful for DSP or graphics. Indeed, the only extant VLIW (that I know of) processor is the Russian Elbrus. I think the VLIW is only included to let them reuse a lot of the core logic of the CPU to drive a DSP engine, useful for radar and scientific simulation, though the sci sim would probably use commercial hardware which would be faster.

It works on GPUs because they're doing DSP, basically. We could have weirder topologies for GPUs however, like a massive string of ALUs driven off an embedded core, so you try to kachunk all your data in a single clock domain after configuring the ALU string.

4) https://github.com/SpinalHDL/VexRiscv