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Comment by initplus | Hacker News Reader

ARM's less open platform also comes with some advantages though. It's easier for ARM to prevent ecosystem fragmentation and non-standard instruction set extensions. Or to push for migrating to newer platforms like the move to 64bit ARM.

Software is less affected by these issues because it's inherently more flexible. If I install some wonky experimental Linux feature, it doesn't really matter and I can just revert. Different story when this is baked into hardware. The startup costs for independents to contribute to a software only ecosystem is also much lower. How many organisations have the talent to contribute to RISC-V, but wouldn't be able to afford purchasing a license?

Didn't mean to sound so negative but I worry in the hardware space that the advantages of such an open design are not as great.

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> ARM's less open platform also comes with some advantages though. It's easier for ARM to prevent ecosystem fragmentation and non-standard instruction set extensions.

It's kind of funny way of looking at the core part of the ARM ecosystem while forgetting how much outside of the CPU is non-standard, undefined. None of the ARM devices share bootloader, device enumeration, and a plethora of things needed for an open, non-fragmented OS/Software ecosystem like how PC does.

Maybe you can run parts of the same ARM machine code on most devices, but it's not terribly portable to be honest, it has to be very generic. For example, Android devices end up in a pile of trash because you can't just upgrade the kernel to the latest version on a 1, 5, 10 year old smartphone without losing functionality or being stuck at step 1 for the lack of tools from broken forum links and shady fileshares. So much for software flexibility...

So you're criticising Arm fragmentation but the possibility of more fragmentation in RISC-V is ok?

My idea is that a CPU is just a component and it's useless by itself without considering the rest of the computer system. ARM needs to dip more into standardising the rest of the picture, and the RISC-V guys could also start looking into creating an open computer architecture initiative/group to prevent further fragmentation.

Agree 100% - Arm could certainly do better.

I do worry though that the RISC-V ecosystem could be really torn in two by a big player (Intel?) who adds proprietary extensions and associated software.

RISC-V is trying to create a standard platform specification to address some of these concerns

https://www.youtube.com/watch?v=l2w4cWFpqAA

The market is already fragmented depending on how you look at it. There are lots of custom chips for all sorts of stuff today which has their own ISA because ARM cannot be used because it imposes the requirement to implement around 1000 instructions.

With RISC-V you could end up with LESS fragmentation, no more. A lot more of the specialized chips can start using RISC-V with particular extensions rather than inventing their own ISA.

That has benefits in that one can reuse more tools and code.

I don't see a reason why RISC-V for desktop systems or high-end smart phones should get any more fragmented than ARM. There is already a standard set of extensions RV32G for these kinds of hardware.

And at least RISC-V has been designed from scratch to handle fragmentation. The base standard gives developers a way to check what extensions are supported in code. It also allows operating systems to include code to simulate unsupported instructions.

RISC-V is prepared for fragmentation in a way that ARM isn't. It is different to design for that possibility and find ways to deal with it as opposed to design around that idea that through strict rules one would avoid fragmentation ever happening.

So ARM's lack of fragmentation means I can install any Android ROM on any ol' ARM device?

Or are ARM devices so crazily fragmented that I need to custom compile for each and every device in existence?

That's the equivalent of saying forking is bad.

The big plus of RISC-V is allowing those who accept the risks and cost to experiment and develop new specialized components. Arm won't let you.

If anything was standardized, Linux wouldn't have the drivers problem.

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