People were commenting on lack of high-performance ARM chips and voicing their skepticism regarding Apple‘s ability to design such a chip. Here I am talking about something different. RISC-V still does not have core components like SIMD or virtualization approved. And of course Apple could develop their own proprietary extensions to fill in the gaps, but what would be the point? It won’t be RISC-V, but rather Apple‘s ISA based on the reduced RISC-V core, requiring them to develop tools and frameworks to work with it. Sounds like a lot of hassle to replicate what they already have with ARM.
Technologies are transient, and I think it makes perfect sence to move on when’s technology has outlived its usefulness. Yes, Apple was the original author of OpenCL, but that initiative has successfully dies thanks to Nvidia and flawed committee politics. ObjectiveC is almost 40 years old now and is in a dire need for a revamp. It was not fulfilling the needs of the ecosystem anymore
ARM64 instead is a new technology that is probably as close to an optimal ISA a register-based architecture can get. It’s only now reaching its critical momentum, and Apple is spearheading the efforts. Why would they abandon it now? There always has to be a reason, some benefit from choosing a different route. I don’t see any in this case.
"RISC-V still does not have core components like SIMD or virtualization approved"
So for starters, there are reasons for SIMD not being a "core" component in RISC-V, that was an intentional design choice, not keeping up with the joneses of whatever SSE/MMX/Neon Intel/AMD/ARM feature parity pissing match that really shouldn't be embraced by a core CPU ISA, indeed, even for Intel, those are *extensions* not a "core" component, further reading on such subjects here:
Is old Cray-1 style vector machines coming back? What exactly is the difference between vector instructions and modern SIMD instructions?
medium.com
Similarly, the RISC-V specifications do have a virtualization mode, perhaps you are referring to the proposed H extension as not yet being approved? As it stands, RISC-V already has more provisions than x86's "real" or "protected" modes, and again, more recent instructions such as VMD, VMX, VMD etc. Intel/AMD64 Virtualization instructions are *extensions* and not "core" components of the original CPU ISA.
"RISC-V specifications describe the current virtualization mode using the symbol V . If
V=1 then the system is currently in guest context, otherwise it is in host context (either supervisor or user mode). The RISC-V H extension introduces a full duplicate of CPU state: one copy for the guest and one copy for the host."
These are not bad things! From my vantage, that shows that the designers of RISC-V have been paying attention and are intentionally jettisoning old cruft, and taking a measured approach with what they want to integrate into their specification. Similarly, not having floppy disk drives is not a real detractor against a contemporary consumer computer in 2021, even if it might have been nearly unthinkable in the 1980s.
RISC-V also does not specify an FPU, but again, if you track research in academia advocating for posits/unum as alternatives to IEEE 754, a standard from 1985, I think we have maybe *just maybe* </saracasm> come a LONG long way since the mid 1980s and do not need legacies baked into a 21st century CPU ISA which began in 2010.
It may make a lot more sense to facilitate better alternatives which are already proposed (and some implemented, in free/libre open source github repositories for posit/unums as well as one firm even offering silicon based implementations) than to drag the 20th century legacies behind us.
Making spurious claims that RISC-V's omission of some things which 1970s and 1980s vintage CPU ISAs have kept dragging along with them, seems disingenuous to me or perhaps misinformed or a really superficial read, from the sort of perspective that maybe can only parse a list of features and see if there is a check mark next to them rather than evaluate whether the check box should even be checked in the first place given the place we are in space and time relative to other advancements.
I think it is OK to leave the past in the past, rather than make erroneous claims that a CPU ISA from 2010 is somehow at a disadvantage to its 1970s and 1980s predecessors, for omitting things which may no longer be particularly useful or relevant, or have better alternatives more worth implementing than suggesting "core" component omissions as somehow being necessarily relevant, let alone suggesting that implies some sort of inferiority.
RISC-V also does not handle fax documents nor RTTY natively. I am OK with that! I would be hella skeptical of any new CPU ISA which considered dated constructs part of its core ISA.
