Felix86: Run x86-64 programs on RISC-V Linux

> Always wondered why RISC-V doesn't get more mainstream adoption.

It's very simple!

Because the amount of time it takes to design and produce a data centre level CPU microarchitecture is greater than the time RISC-V extensions needed for data centre CPUs have existed.

The original RISC-V specification was ratified less than six years ago, but you really couldn't create a data centre CPU until at least RVA22, ratified two years ago in March 2023 -- or preferably RVA23 which was ratified in October 2024 and has the features needed for efficient hypervisors.

You can knock out a microcontroller CPU core in a weekend, but something to compete with current Apple, AMD, Amazon etc CPUs takes a long time to make. Most companies doing that started work only in 2021 or 2022.

It is simply too soon. A lot of stuff is in the pipeline.

Any price advantage, even if we assumed a fully mature ecosystem with equivalent processors and systems available, is massively overstated. ARM had a total revenue of just ~3.7 G$ in 2024 over ~29 billion chips [1].

In contrast, Qualcomm, just one of many large suppliers of ARM-based systems, had a total revenue of ~39 G$ and a operating income of ~10 G$. ARM's entire revenue would easily fit into Qualcomm's profit and only increase costs by ~12%. And that is just one supplier. You have Samsung, Apple, Broadcom, Google, Amazon, Nvidia, TI, NXP, etc. to help round that out.

The total impact of ARM licensing and IP costs is almost certainly less than 1%. And given that RISC-V does not currently have a fully mature ecosystem, you get to trade that for a 1% cost improvement; not really a winning strategy right now.

It is likely the main advantage in the long run for RISC-V is that not requiring a license might enable a more vibrant ecosystem due to removing the licensing barrier which might enable better designs at comparable costs (because, again, the cost differential should only be on the order of 1% in the long run) rather than just creating comparable designs that just chip off the licensing cost. That or RISC-V could win because the giant manufacturers feel like putting the squeeze on ARM to drive 1% off their BoM.

[1] https://www.acquired.fm/episodes/how-arm-became-the-worlds-d...

What fraction of the total cost of operating a datacenter do you suppose goes into ARM licensing? That's how much more efficient than RISC-V an ARM would have to be in order to make it the preferred CPU in a "we don't need x86" scenario. That's a very low bar to clear (for ARM, not for RISC-V)

From what I've seen, most RISC V chips are still far behind x86 and ARM when it comes to raw power. I don't think the loss in performance is justifiable with lower cost (yet)

They're significantly slower than x86 and ARM at the moment.

I think there has been a big uptake in things you don't see like embedded or FPGA cores but as a general CPU it's nowhere near as efficient as ARM/x86 right now is my understanding. So it might be running in the SSD and the Fan controller but not as the CPU. I think a large part of the cost of a CPU core is not the instruction set but the optimisation of the CPU and ARM/Intel/AMD are still way ahead in those. And so it needs people to optimise the cores, which when they have done that they charge for being a better CPU.

> Always wondered why RISC-V doesn't get more mainstream adoption.

For me, it's because the ecosystem has fragged even harder than Xtensa, who will sell you custom CPUs. THead made yet another vector unit that's required to approach anything near the Intel/AMD moat numbers.

SpecInt/GHz last year was around half of Intel/AMD/ARM numbers.

The imminent demise of CISC has been trumpeted from the rooftops for at least the last 30 years...

There's a fair bit of adoption where you don't see it (for example, if you have an NVidia GPU or a WD hard drive, you likely have a few embedded RISC-V cores already). We're expecting server hardware with good performance in a year or two.

Almost heh https://www.reddit.com/r/RISCV/comments/1jfkng6/windows_stea...

The felix86 compatibility list also lists SuperTux and SuperTuxCart.

"lsteamclient: Add support for ARM64." https://github.com/ValveSoftware/Proton/commit/8ff40aad6ef00... .. https://news.ycombinator.com/item?id=43847860

/? box86: https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...

"New box86 v0.3.2 and Box64 v0.2.4 released – RISC-V and WoW64 support" (2023) https://news.ycombinator.com/item?id=37197074

/? box64 is:pr RISC-V is:closed: https://github.com/ptitSeb/box64/pulls?q=is%3Apr+risc-v+is%3...

I am hopeful valve will release a risc-v build themselves.

And wine/proton will integrate with this or some similar solution for running x86 binaries.