4 ms·
RISC V is an opinionated architecture and that is always going to get some people fired up. Any technology that aims for simplicity has to make hard choices and
by socialdemocrat 5y ago
RISC V is an opinionated architecture and that is always going to get some people fired up. Any technology that aims for simplicity has to make hard choices and trade offs. It isn’t hard to complain about missing instructions when there are less than 100 of them. Meanwhile nobody will complain about ARM64 missing instructions because it had about 1000 of them.
Therein lies the problem. Nobody ever goes out guns blazing complaining about too many instructions despite the fact that complexity has its own downsides.
RISC-V has been designed aggressively to have minimal ISA to leave plenty of room to grow, and require minimal number of transistors for a minimal solution.
Should this be a showstopper down the road, then there will be plenty of space to add an extensions that fixes this problem. Meanwhile embedded systems paying a premium for transistors are not going to have to pay for these extra instructions as only 47 instructions have to be implemented in a minimal solution.
- klelatti 5y agoFair point but Arm is not just Arm64 - if you want a simple low cost ISA then there is Cortex-M.
- imtringued 5y agoIt reminds me of nutrition advice. The 70s said X is evil or bad. Then we discover, X doesn't matter. I think in 10-20 years everyone will agree that all the "bad" RISC-V decisions don't matter. The same way x86 (CISC) was supposed to be bad because of legacy/backwards compatibility.
- DeathArrow 5y agoI remember Jim Keller saying that for every ISA just 7 or 8 instructions are important and they are used for like 99% of the code. Load, store and the like.
- rep_lodsb 5y agoThat doesn't mean we should eliminate everything else. Many operations that would require 3 or more simple instructions are easy enough to implement in hardware, so that they take no more time than one of these simple instructions. This can be a big win even if they are only used 1% of the time.