Future Arm CPUs will drop 32-bit support, and here’s what that means

Paul Williamson, VP and GM of Client Business at Arm, announced at a keynote speech by Arm DevSummit that future Arm Cortex-A CPU cores – for future smartphones, for example – will not become 64-bit cores until 2022. This means that no hardware is supported for old 32-bit applications in the future that signal small but important effects on future smartphones and the Android operating system.

If you are concerned about app support, fear not. Since August 2019, Google has required all apps submitted to Google Play to be 64-bit. Arm also notes that around 60% of apps are already 64-bit compatible. Most of those who aren’t 64-bit don’t fall into Western ecosystems like Apple and Google anyway. In other words, most applications are already 64-bit capable and there is still plenty of time to prepare for the transition. One or two older applications that are no longer serviceable may simply no longer work.

Isn’t Android 64-bit already?

Technically yes. Android introduced 64-bit support with 5.0 Lollipop back in 2014, but the Android and Arm’s CPU cores still support older 32-bit applications. So Android is not exclusively a 64-bit operating system, at least not yet. It’s this legacy support that will end in 2022 from a hardware standpoint, and Google will certainly follow suit with Android. From the user’s point of view, the transition should be largely seamless.

The benefits of moving to 64-bit include only improved performance for applications, games, and operating systems, which can be up to 20% in some situations. Developers no longer have to support two binaries and can instead focus on optimizing just a single 64-bit binary. This could lead to faster update times.

See also: Windows on Arm is finally getting 64-bit support

In many ways, the move to 64-bit will work as usual. Smartphones and applications have been in transition for years. It’s time for both the hardware and software to complete the transition. After all, Apple’s iOS 11 only went to 64-bit in 2017.

What we know about poor 64-bit CPUs

The big news for Arm is that it can finally remove extra silicon from its CPU designs that it needs to support 32-bit legacy. This saves silicon area, which can mean smaller and cooler CPU cores or more powerful functions with the same size.

The code names for the Cortex-A CPUs 2021 and 2022 from Arm are Matterhorn and Makalu. The latter will only be converted to 64-bit. Arm promises a 30% increase in performance between the 2020 Cortex-A78 CPU and Makalu, so there are still big wins in the pipeline.

The transition to 64-bit only begins with the large Cortex-A CPU cores. The move to 64-bit exclusivity doesn’t necessarily coincide with a new architecture like ArmV9. In other words, we’re probably looking at CPU cluster designs that only mix 64-bit Makalu with a smaller 32/64 bit CPU like the Cortex-A55. Although the end products will only be 64-bit from a developer and user perspective.

It will be a while longer before we see just a small 64-bit core complimenting the large core, leaving the door open so that lower-powered devices can continue to support 32-bit longer. There are indications that a small CPU core may replace the Cortex-A55. Although such a core still has 32- and 64-bit support to ensure a smooth transition.

Moving to 64-bit is a big deal for Android, developers, and poor alike. This is an important step in easing the current tangle of legacy support. However, it won’t mean a fundamental change in the end user’s ecosystem and day-to-day experience. As long as app developers make the transition – and there’s plenty of time to do that – consumers are unlikely to even notice the switch.

Further information on arm CPUs: Arm Cortex-X1 and Cortex-A78 explained