ARM has been designing chips that support 64-bit software for years, but the company has also continued to support 32-bit code.
That’s going to change in a few years. Kind of.
ARM has announced that starting in 2022 all of its “big” CPU cores will be 64-bit only. But that leaves open the possibility that ARM will continue to offer 32-bit support for new energy-efficient chips that use its “LITTLE” CPU cores.
So odds are that this means if you buy a new high-end phone, tablet, or PC in 2022 and it’s using the latest ARM processors, it will probably only be capable of running 64-bit applications.
ARM’s big.LITTLE technology allows high-performance (and more power hungry) CPU cores to be paired with lower-power efficiency cores on a single chips. I suspect that if the “big” cores are 64-bit only, that means most chips using this sort of design will also be incapable of running 32-bit software starting in 2022.
Some cheaper phones and tablets, however, use chips that only use LITTLE CPU cores, and in that case, it seems possible that 32-bit software may continue to be supported for some time to come.
So why the switch? According to ARM, the 64-bit instruction set brings “performance improvements and compute capabilities” needed for “complex digital immersion experiences that consumers are demanding,” and even simply recompiling a 32-bit app to 64-bits brings a performance improvement and security enhancements.
ARM says it expects the chip designs it delivers in 2022 to bring a 30-percent performance boost over current-gen ARM Cortex-A78 CPU cores, and the company has laid out a bit of a timeline for its next-gen and next-next-gen processors, with:
- “Matterhorn Generation” coming in 2021
- “Makalu Generation” coming in 2022
Focusing on 64-bit also gives software developers a single target instead of two targets… although it does come with some risks for users. If you’ve been relying on older applications that have been abandoned by their developers and which haven’t been updated in years, they may not work on devices with newer ARM chips a few years from now… unless you’re using a budget phone that only has LITTLE CPU cores.
I would add: implementing 32 bit ISA requires transistors, i.e. it’s no free, it requires silicon and consumes power. If you remove 32 bit instructions, you get a better core, because the saved transistors makes chip cheaper and less power hungry, or you can have the same transistors but use those used in 32 bit to add cache or other functions that add up.