Help me understand this better.
From what I have read online, since arm just licenses their ISA and each vendor’s CPU design can differ vastly from one another unlike x86 which is standard and only between amd and Intel. So the Linux support is hit or miss for arm CPUs and is dependent on vendor.
How is RISC-V better at this?. Now since it is open source, there may not be even some standard ISA like arm-v8. Isn’t it even fragmented and harder to support all different type CPUs?
I don’t think there has been huge issues with incompatible ISAs on ARM. If you’d use NEON extensions, for example, you might have a C-implementation that does the same if the extensions are not available. Most people don’t handwrite such code, but those that do usually go the extra mile. ARM SoCs usually have closed source drivers that cause headaches. As well as no standardized way of booting.
I haven’t delved super-deep into RISC-V just yet, but as I understand these systems will do UEFI, solving the bootloader headache. And yes, there are optional extensions and you can even make your own. But the architecture takes height for implementing an those extensions in software. If you don’t have the gates for your fancy vector instruction, you can provide instructions to replicate the same. It’ll be slower on your hardware, but it’ll be compatible if done right.