![]() ![]() If you’re wondering why SoCs are being productized with a mix of 32/64-bit capable cores in the first place, the reason is that there are still markets where 32-bit apps are being distributed. This document explains in-depth how Linux’s task scheduler will handle the asymmetry if you’re interested in more details. However, the introduction of CPUs with some cores that can execute 32-bit tasks and some that cannot changes the equation the scheduler distributing tasks to a CPU core incapable of executing that task could be detrimental.įortunately, kernel engineers at Arm and Google were well aware of this impending problem, so late last year they began work on a series of patches to support asymmetric 32-bit SoCs, which kernel engineer Will Deacon hilariously described as systems built by “some crazy folks.” These patches have been picked to the mainline and android12-5.10 Android Common Kernel branches already, so Android devices with the latest chipsets from Qualcomm or MediaTek will almost certainly have this feature. As explained in this LWN article, Linux’s task scheduler was designed to assume that all CPUs can run any given task, albeit at different performance or power consumption levels depending on the specific core chosen for the task. This, at first glance, seems problematic given the way CPU affinity works in Linux. That means 2022’s flagship smartphones will only use three of their eight CPU cores to execute 32-bit apps. ![]() MediaTek’s flagship Dimensity 9000 chipset, which was announced just two weeks ago, has a similar core configuration. The CPU features one Cortex-X2 core, three Cortex-A710 cores, and four Cortex-A510 cores, but only the three Cortex-A710 cores support execution of 32-bit applications. Before that happens, though, we’re about to enter a weird transitional period thanks to the launch of asymmetric 32-bit SoCs from Qualcomm and MediaTek.Įarlier this week, Qualcomm announced the Snapdragon 8 Gen 1, the company’s first system-on-chip to use the Armv9 ISA. Android as an OS platform won’t deprecate 32-bit support for quite a while, but we’re finally nearing the point where the first devices will ship with 64-bit only support. That’s despite the fact that the Armv8 ISA introduced the AArch64 execution mode back in 2011, Android 5.0 Lollipop introduced platform-level support for 64-bit apps in 2014, and Google Play mandated that apps support 64-bit CPUs in 2019. Google, on the other hand, does not exert the same level of control over the hardware that can run Android or the methods of app distribution, so Android still supports running 32-bit applications to this day. It took the company just four years to transition iOS from 32-bit to 64-bit only software, a remarkably quick turnaround made possible by Apple’s total control of its hardware, the iOS operating system, and the App Store. Back in 2017, Apple ended support for 32-bit applications with iOS 10.3.2, dropping compatibility with old, unmaintained apps from the dawn of the smartphone. ![]()
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