The Linux Kernel’s Evolving Landscape: Phasing Out Legacy 32-bit Arm Support
The Linux kernel is a marvel of continuous evolution, constantly adapting to new hardware while strategically shedding support for deprecated systems. This article dives into the significant changes coming with Linux 7.3 and 7.4, specifically the proposed removal of legacy 32-bit Arm platform code. For tech-savvy readers invested in the ‘Linux’ category, understanding these shifts is crucial. We’ll explore which Arm platform components are being phased out, the rationale behind these decisions, and what it means for legacy hardware support. Prepare to unravel the kernel’s dynamic nature and its ongoing commitment to streamlined development.
Understanding Linux Kernel Evolution
The Linux kernel development cycle is relentless, balancing the introduction of cutting-edge features with the necessary task of maintaining a robust codebase. Recent proposals by Arnd Bergmann aim to prune a significant chunk of 32-bit Arm platform code, marking a pivotal moment for system developers and users alike. While the initial patches target the upcoming Linux 7.3 release for deprecation, the actual removal is slated for Linux 7.4, expected in late 2026 or early 2027. This long-anticipated cleanup, which Bergmann has championed for years, is finally gaining traction, promising a leaner, more focused kernel.
Deprecating Legacy Arm Platform Code
This extensive cleanup effort, comprising around 300 patches, focuses on removing the arch/arm/mach-* code and its associated Kconfig bits. These components are tied to a bygone era of computing, supporting hardware that has largely become irrelevant in modern contexts. The goal is to reduce the maintenance burden and free up development resources for current and future architectures.
The Hardware Being Phased Out
The list of platforms losing mainline kernel support reads like a nostalgic trip through late 1990s and 2000s embedded systems. Specifically, the following hardware will no longer be supported by mainline Linux kernels from 7.4 or 7.5 onwards:
- SA1100 boards
- Acorn RiscPC
- Footbridge
- Legacy PXA board files
- Orion, Dove, and MV78xx0 boards
- OMAP24xx, i.MX31, and no-MMU i.MX chips
- LPC18xx and Axxia
- STM32F4, F7, and H7 microcontrollers
- Versatile MPS2
- AT91 SAMV7
It’s crucial to clarify that existing devices on these platforms won’t suddenly cease to function. Instead, they will simply be unable to run newer mainline kernels, as the necessary booting code will be deleted. For users of these systems, continuing with an older, stable kernel version (preferably an LTS release) or exploring custom kernel modifications will be necessary.
The Balancing Act: Old vs. New Hardware
The removal of legacy hardware support isn’t arbitrary; it reflects the continuously shifting priorities of Linux kernel development. The same 7.3 cycle that deprecates older Arm platforms has simultaneously gained support for a host of cutting-edge Arm-powered chips. Recent additions include Apple’s M3 Pro, Max, and Ultra, Samsung’s Exynos 1580, and Qualcomm’s Shikra. This illustrates the kernel’s dynamic nature: it must regularly adapt to emerging technologies while also strategically retiring support for hardware no longer widely used or maintained. This ensures the kernel remains efficient, secure, and performant for the vast majority of its user base.
Linus Torvalds’ Stance on Code Pruning
Linus Torvalds, the creator of Linux, has historically been a strong advocate for removing outdated code. His proactive approach was evident in 2022 when he questioned the continued support for i486 CPUs, recalling the earlier removal of i386 support in 2012. By 2025, Torvalds asserted there was no compelling reason for developers to expend efforts on these platforms. Given this precedent, it’s highly probable he will greenlight these Arm platform removals, provided there are no unforeseen issues. This foresight keeps the kernel lean and focused on future innovations.
Your Voice Matters: Advocating for Legacy Systems
Despite the clear direction towards code removal, the Linux kernel community remains open to discussion. Arnd Bergmann has explicitly left a window open for anyone wishing to argue against the removal of specific drivers or legacy hardware support. This highlights the community-driven nature of Linux development, where even deeply technical decisions can be influenced by strong, data-backed advocacy. If you rely on one of the listed legacy Arm devices for a critical application, now is the time to engage with the kernel mailing lists.