Hacker News Reader

Comment by Nokinside | Hacker News Reader

RISC-V ISA is just a programming interface and non-physical IP.

The license fees for ARM Processor families are mostly for physical IP for microarchitecture.

ARM provides selection of 40+ highly optimized physical processor IP cores for different purposes. Maybe you get eventually similar selection RISC-V architectures but they are not free. It takes lots of full time work to test and optimize those cores. If you write processor core implementation in verilog and give it away free you have done just 10% of the work.

View on HN

Physical IP for up-to-date silicon fab nodes is never free. But SiFive is already providing it for RISC-V - and other vendors could easily get involved too, seeing as good high-level designs (that can be simulated in FPGA with relative ease) are available with permissive licensing.

Sure, but from the pov of a startup that needs a core, the choice is whether you pay SiFive or similar, or ARM.

> Physical IP for up-to-date silicon fab nodes is never free.

This is baffling. My understanding of how a startup that wants to make its own custom CPU would work is this:

- Write Verilog or HDL sources for your CPU

- Test your CPU in sims and FPGA's, fix any bugs in the Verilog

- Send the Verilog files off to a fab

- Write a check in the $1 - $10 million range for the fixed-cost component of production (i.e. the mask)

- Get a shipment of ASIC chips for like a $1 unit cost

- ??? (your specific business model)

- Profit

Are you saying nobody has open-sourced Verilog files for a RISC-V CPU? This seems like something that's easily within the resources of volunteers, and is probably actually less work than all of the kernel and toolchain support.

Arm's competitive edge will whither, since other companies are frantically working on RISC-V implementations!

What the hell is "Physical IP". Last I heard you either had IP or you had just plain old physical property. Not a weird combination of both.

It sounds like some convoluted way of making an end run around first sale doctrine by saying you bought the atoms that make up that processor, but you didn't purchase the arrangement of them; which sounds absolutely absurd.

Or am I missing something?

It's an industry-specific term. "Physical IP", as in the opposite of "logical IP", does not refer to atoms, but to a low-level specification ("netlist") of the transistor layout of computer chip components. You could compare it to machine code that is optimized for a very specific processor.

That is juxtaposition of terms is unfortunate... but thank you for clarifying. It's still IP, just in the form of a specification for physical components.

Better explanation:

Physical IP is the CPU design at the transistor level.

Logical IP is a spec document saying how the processor should work, plus a bit of pseudo code and maybe a simulator or two.

Reply on news.ycombinator.com