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From: jgd@cix.co.uk (John Dallman)
Newsgroups: comp.arch
Subject: Re: Computer architects leaving Intel...
Date: Fri, 30 Aug 2024 15:48 +0100 (BST)
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In article <2024Aug29.135124@mips.complang.tuwien.ac.at>,
anton@mips.complang.tuwien.ac.at (Anton Ertl) wrote:

> Concerning the demand, RISC-V has the advantage of no ARM tax (and
> legal costs like those between ARM and Qualcomm over the 
> developments started at NUVIA)

True, although the market for high-performance application cores is less
price-sensitive than the market for low-performance embedded ones. 

> Another RISC-V advantage is that the government of the USA puts
> restrictions on ARM that should not apply to the free RISC-V
> architecture.
> 
> It would apply to implementations designed in the USA (such as those
> by Ahead), but the point is that on the ISA level, and thus the 
> buy-in into the ecosystem (e.g., from ISVs), RISC-V has an advantage.

As someone who does porting and platforms for an ISV, I'm seeing no
customer demand whatsoever. I'm pretty sure that's because of the lack of
high-performance implementations. I'd like to do RISC-V, because new
architectures are fun, but I can't get hardware at present that's up to
the job, and so I can't justify spending time on it. 

> RISC-V also has a technical advantage over ARM: It has Ztso (total
> store order) as an optional extension, which helps porting of
> multi-threaded software from AMD64 (and emulation of AMD64 
> software). No such thing on ARMv8 or ARMv9 yet, although
> implementations like the Apple M1 and Fujitsu A64FX provide 
> this feature.

Yup, that's an advantage. I have not had trouble with the lack of it on
multi-threaded ARM Linux or ARM Windows, but the threading framework I
use was originally developed on SPARC and does its mutexes properly. 

> > But it's also possible they just want to carry on being chip 
> > architects while being in charge of their own company.
> Sure.  But what are the investors seeing in the company?

Hard to say, given the things venture capitalists are prepared to throw
money at these days. 

> Even if an architecture has a long track record, like MIPS, that's 
> not enough, as the switch from the MIPS ISA to RISC-V shows.

In my market sector, so far, that's "the death of MIPS." That happened in
2008, simply because it wasn't remotely performance-competitive. 

> What I read is that the Snapdragon X implements ARM v8.7.

You're right, I mis-remembered. 

John