[GTALUG] risc-v seems to be gaining traction

[Lennart Sorensen]

On Mon, Mar 22, 2021 at 09:44:15PM -0400, D. Hugh Redelmeier via talk wrote:
> Most Amazon comsumer products contain ARM.  But they are just part of SoCs 
> that ARM buys (it doesn't design or produce them).  Of course that could 
> change, but why?

Certainly most Android devices run ARM, with a few x86 exception.

> The main Amazon exposure to ARM is the Graviton processor.  I *think* they 
> buy the design of the ARM core used in that chip from ARM corporation.  
> Nobody yet has a RISCV core for sale that is as fast.  Amazon could 
> develop one in-house but that would probably take several years.

Graviton 2 is ARM Neoverse N1 core, so a standard core.  Graviton 1 is
ARM Cortex A72 cores so also standard cores.

> My guess: a clean sheet RISCV design could beat an ARM, modestly.  That's 
> because, after all these years, the ARM architecture has quite a few 
> barnacles.

ARMv8 actually cleaned up a lot of legacy from the design, and a number
of ARMv8 designs don't include any backwards compatibility (so they
can't run ARMv7 or older code at all).

> Apple designs the cores of its ARM implementations.  But they have a 
> pretty good license perhaps from the founding of ARM (with Acorn).

Anyone can buy a license to design their own ARM implementations.
They cost more than a license to just use standard ARM designed cores.
Not unusual though.  Qualcomm, Marvell, Apple, Applied Micro, Nvidia,
Cavium, AMD, Samsung and probably others have done custom ARM compatible
cores.

> It's hard for Apple to switch because of the binary software distribution 
> model.  They are just starting to migrate users from X86-64 to ARM.
> Quite a history:
> Motorola 68000 => Power => x86-32 => x86-64 => ARM64

Apple has done it multiple times, and have managed to use software
emulation to handle the transision.  They will be fine.  Of course
given the iphone and ipad (we will pretend the newton never happened
although it was partially responsible for ARM being around today)
have been ARM forever, so it makes sense for Apple to expand the use
of their own custom ARM designs to the laptop and desktop market too.
No need to depend on what intel decides to make going forward.  They had
enough trouble with what IBM and freescale(motorola) was making in the
past that didn't suit their future, and intel's failure to bring up new
wafer processes probably doesn't inspire confidence at Apple.

-- 
Len Sorensen