RISC-V Implementation


#21

Note that the reason the SiFive board is so expensive is low volume production… they are probalby making only hundreds or a few thousand of them, and mask costs are astronomical.

Once they are making millions of them the mask costs are amortized to basically nothing… and you get chips that are as cheap as the wafers they are made on… so a few bucks for something the size of a SiFive at most.


#22

The trustzone firmware is encrypted… the trustzone ARM CPU itself is nothing special. The same would go for RISC-V in that role… only signed firmware can execute, and that is encrypted.

Also RISC-V’s license does not preclude proprietary extensions as it is BSD licensed not GPL which is another reason OpenRisc and OpenSparc were flops, the industry couldn’t extend them and profit from them.

They might replace TrustZone as the Risc-V version is probably cheaper to license or easier to modify/validate, there could be many reasons there.


#23

Ah, I get it. You win… this time :wink:


#24

We’ll until they come up with something a bit more impressive than a $1k dev board… we’re all in the same boat of it being too expensive for our use so… hopefully they fix that soon.

A bit off topic still but a RISC-V implementation I expect to show up in alot of products is this https://hackaday.com/2018/10/08/new-part-day-the-risc-v-chip-with-built-in-neural-networks/

A 400Mhz dual core 64bit RISC-V + 8MB sram + 0.25 Teraop neural network processor (uses about 300mW at those specs) OCable to twice that fast 800Mhz + 0.5 Teraops on the NN processor… really impressive by any measure. Note that it is also extremely cheap… like under $5 for the chip $15 for a full dev board (chip + board + camera + LCD). Sadly it doesn’t have an external ram interface so no way to boot larger operating systems on it though it’s plenty fast enough.


#25

Couldn’t some development be done with virtual machines?


#26

Yes but at some point you need real hardware to prototype real devices… an emulator only lets you test the software side of things not the hardware side.


#27

https://git.haiku-os.org/haiku/commit/?id=dd485ed444a35c06cb9a8e87416129b5227bdf02

@kallisti5 taps his nose.


#28

It would probably be better for Haiku to get a head start via emulators, and Haiku, Inc. makes more than enough money to buy one of SiFive’s developer boards for Haiku developers to use.


#29

It would be better for Haiku to expend it’s efforts on things that are more relevant.

As I’ve already said RISC-V isn’t really ready for desktop use this is more of a Router board… and money on that dev board would be mostly wasted as it doesn’t even have video out. It doesn’t even have PCI-e perhaps when they release a board with PCI-e it might be worth a look. Also by the time they add those features they may change the design of the platform somewhat meaning wasted work.

If someone wanted to work on it in an emulator that would be cool though…


#30

We turn the page back to 320 MHz 32-bit processors…

Hobbyists will find products like Xilinx Artix-7 35T Arty and LoFive’s RISC-V. This will lean towards embedded developments which is a nice focus for outdated (i.e. no longer manufactured or supported) architectures.

Also, note that the original Amiga/Atari computers were pushed with 25Mhz - 233 MHz processors. RISC-V is a nice idea to emulate and support old 16/32-bit computers and gaming consoles with some expansion.

A lot of old embedded controllers/systems are still in use without high-end performance needs…

Remember that many of these dev boards get customized for low-cost (LoFive) to high-end markets (Unleashed). Also, with coprocessors for other needed areas (PCIe, etc)


#31

I’m not sure what you are saying?

I wasn’t saying that RISC-V doesn’t have the potential to be a desktop CPU… just that it is not ready for that at all yet. PCIE isn’t something you can add on with a coprocessor… to a CPU that doesn’t integrate it natively.

I also wasn’t saying that RISC-V doesn’t have the necessary performance… I’d say it probably is fast enough for many Desktop needs. A1.5Ghz 64bit dual core is pretty OK for very basic use if you can add ram and expansion cards to it.


#32

In Dec2018 we expect to see an announcement from Esperanto Technologies, founded by Dave Ditzel (the Transmeta founder, also worked on Sparc). They hired the BOOM guy (Christopher Celio) and a few other well know chip designers, and are planning a 4096 Risc-V core machine, running at comparable frequencies as the big boys. This chip should turn a lot of heads. Also, the next gen SiFive chips should tape out at 14nm, so expect a device comparable to RPi3 - but with Risc-V instruction set.

Can Process Controller cope with a 4096 core beast?

One important benefit the Risc-V architecture brings to the mix is excellent code density - they typically have 5-10% smaller binaries, which should translate to less pressure on instruction cache (and better performance). Time will tell …


#33

[citation needed]

Sounds interesting, anyways.


#34

Sounds like it would be similar to Tilera which is mesh networked MIPS cores.

Note that such architectures usually don’t work well with standard operating systems and software… You have to specifically code for parallelism. Same problems there as Intel’s larrabee…

Also it probably has an underwhelming memory interface…compared to the core count so they mostly only operate on streams of data or out of cache to avoid stalling the whole thing out etc… Something that happened alot on IBM’s cell processor.

Also to fit that many CPUs they would be simple cores, offering very little single threaded performance even at highish 2-3ghz clocks.


#35

I highly agree with this thread. :slight_smile:
The price of the new SiFive HiFive Rev B has come down from $59 -> $49 and includes wifi + bluetooth.

It’s only a matter of time until the price of the more powerful 64-bit SiFive hifive-unleashed comes down (and other players enter the market).

The velocity is fast on it. Look how quick the RISC-V gcc port moved. Heck, Fedora 29 has a full-blown qemu RISCV64 target (qemu-system-riscv64)


#36

This exactly why people still use Mac and Windows…