
RISC-V: More Than a Core - walterbell
https://semiengineering.com/risc-v-more-than-a-core/
======
chubs
I'm concerned that the many RISC-V projects seem to be stalling, I'd love to
be convinced otherwise?

* It's been almost 2 years since SiFive released their arduino-ish dev board and it hasn't been updated, surely there are huge gains in 2 years in such a fledgling ecosystem? I feel this is important because this board seems the obvious entry point into the RISC-V ecosystem for enthusiasts.

* The 'BOOM' processor which showed many efficiency gains doesn't seem to be getting anywhere further than last time i checked on it which was perhaps a year or more ago. -edit- looking on their github releases, 2.1 was 6mo ago, and 2.1.1 was recent but shows minor changes, the project unfortunately looks stalled to me.

* LowRISC which has one or two of the RaspberryPi co-founders on board, which seems to be a good sign as far as 'getting something out the door' \- i can't seem to see any output from their project?

Please prove me wrong, i'd like to get involved somehow but i have to be
careful where I invest my time :)

~~~
pippy
There has been a decent amount of projects recently. Andes Announced 1.2 GHz
CPUs made on 28nm die, and a Chinese company are taking orders for a 400MHz
dual-core AI chip. SiFive at the start of the year did start selling HiFive
Unleashed, but it is very expensive.

The Berkeley processor is mostly a research CPU for FPGAs. I would however
love to see it on actual silicon.

At a guess i'd say it will be a few years until we see RISC-V popping up in
more places.

~~~
tyingq
_" I would however love to see it on actual silicon."_

Qty 1, but...
[https://mobile.twitter.com/boom_cpu/status/10324470709283962...](https://mobile.twitter.com/boom_cpu/status/1032447070928396289)

~~~
chubs
No kidding, that's impressive! That was a couple months ago now, i wonder if
they've got it connected to a board/RAM and working ?

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Lind5
While RISC-V continues to grow, there are still gaps that may limit where
RISC-V is used in designs [https://semiengineering.com/risc-v-inches-toward-
the-center/](https://semiengineering.com/risc-v-inches-toward-the-center/)

~~~
microcolonel
Sure, but filling those gaps is the ongoing work of the foundation. The vast
majority of ARM penetration is highly generic, ditto MIPS and Tensilica (e.g.
my aftermarket camera lens has some 32-bit MIPS core in it, and doesn't call
into MSA; this code could be compiled, assuming equivalent peripherals, to run
on a standard RISC-V today and perform the same task).

------
pdimitar
The article says:

> _One of the big benefits of RISC-V is that the architecture is open source._

To which I reply:

...Yeah, until Intel / AMD / Qualcomm / WhatHaveYou Corp.™ say that the
implementation below is proprietary and must be defended with a copyright law.
And probably compilers for Intel RISC-V CPU and AMD RISC-V CPU will be
different because of a vastly different microcode. :(

I want to believe in RISC-V but I am afraid the current incumbents will find a
way to capitalize on the idea without showing any goodwill or actually working
together... in just a few short months. Never underestimate a team of expert
lawyers and marketers I guess.

And I _really_ wish that I am wrong. I will follow any RISC-V news eagerly.

~~~
IshKebab
I think that's a far smaller risk than fragmentation. Without one company to
control the ISA are we going to end up with a gazillion variants and
extensions? How do you compile a program for that?

Hell there are already a ton of variants defined in the base standard. I guess
at the moment they are targeting embedded systems where it's reasonable that
you compile your program specifically for one chip. Hard to imagine that
working on the desktop though.

~~~
agalunar
I suppose “variants” is not an inaccurate description, but it feels misleading
(although you could argue about intention vs reality). The spec calls them
“extensions”. Support for an extension can be checked at runtime, and
unsupported instructions can be trapped and emulated. The base ISA is frozen,
and the common extensions (floating point, atomics, vectors) are standardized.
The spec also defines a subset of the extensions that general purpose
processors are expected to support.

It may be a hope born of bias (I’ve worked with the architects of RISC-V), but
I don’t expect fragmentation to be one of the primary issues that RISC-V will
face.

~~~
pdimitar
I am no expert but...

> _Support for an extension can be checked at runtime, and unsupported
> instructions can be trapped and emulated._

...isn't that exactly fragmentation?

~~~
agalunar
I’m no expert either, and maybe there’s a precise definition of fragmentation
that I’m not aware of. My understanding is that fragmentation is about
software.

The extension scheme allows you to use the same binaries across all platforms.
If you care about widespread compatibility, you simply compile-in software
emulations of potentially unsupported instructions. If a platform ~does~
support the instructions, the emulation is never used and you get a
performance bonus.

------
sitkack
> A previous project, open core 32, was a vibrant open-source hardware group
> in Europe. But what they made open was an implementation of a processor.
> With RISC-V, what is open is the instruction set, and you can use that to
> implement anything from the smallest IoT device to server-class processors.

So open core 32 was an open implementation, RISC-V is an open idea. Sometimes
an idea travels farther, faster, if it doesn't have an implementation. And the
implementations that do exist, have a huge population of creators (rapid fans)
to assist in its spread and usage. Brilliant. RISC-V isn't the Linux of
hardware, it is the Unix.

~~~
listic
This one? [https://opencores.org/](https://opencores.org/)

------
bhasi
I see a sound byte from SiFive. Would have been nice if they had reached out
to Shakti for their comment as well.

------
microcolonel
That IBS chart seems a bit baloney, why does the cost and cost share of
_software_ grow so dramatically at smaller nodes? It seems like most of the
cost share increase would come from validation and physical design.

I personally think that at this point, success (and hardware interest) in
commodity RISC-V server hardware is mainly contingent on the availability of
major compilers and runtime libraries, but that is necessary regardless of
process technology. I don't know of many operators/users of server hardware
who have any considerable investment in any ISA-locked software (except the
odd proprietary package which would not honestly be too difficult to convince
vendors to basically just recompile).

~~~
mrob
>why does the cost and cost share of software grow so dramatically at smaller
nodes?

My guess is that the main reason is market segmentation. If you're willing to
work at a smaller node, then you're willing to spend more money, and the
software vendors can charge more.

~~~
IshKebab
I'm pretty sure that is the development cost for the compilers, etc. You're
not paying some other company to do that.

~~~
microcolonel
Yeah, I initially got the impression they were talking about the design
automation software for the node, but I'm not really sure if that's the case.

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inamberclad
This site managed to disable right clicking?

~~~
tyingq
Yes...annoying. It's in the main html as an embedded script:

    
    
      function nocontext(e) {
        return false;
      }
      document.oncontextmenu = nocontext;
    

You can paste "javascript:void(document.oncontextmenu=null);" into the address
bar to get it back.

~~~
kevincox
In Firefox Shift+Click bypasses this shenanigans as well.

~~~
a_wild_dandan
I'm seeing no shenanigans in Firefox. The context menu works for me.

~~~
devcpp
And it works for me on both Firefox and Chromium, uBlock disabled. I can't
find the function in the HTML either. Was it just removed?

~~~
tyingq
Yes, looks like someone removed it. It's still in the source on the wayback
machine cached copy:

[https://web.archive.org/web/20181015143110/https://semiengin...](https://web.archive.org/web/20181015143110/https://semiengineering.com/risc-
v-more-than-a-core/)

That cached copy also seems to show the site was hacked for a while. Search
the source for strings like "provigil free trial coupon".

Edit: It's still hacked. See
[https://www.google.com/search?q=site%3Asemiengineering.com+v...](https://www.google.com/search?q=site%3Asemiengineering.com+viagra&oq=site%3Asemiengineering.com+viagra)
Clicking on any of the results takes you through a redirect to a shady pharma
site.

