Linux kernel developers are renewing efforts to retire the x32 application binary interface (ABI), a little-used compatibility feature that attempted to combine the advantages of 64-bit processors with the smaller memory footprint of 32-bit applications. A revised patch series submitted on October 8, 2026, proposes the first steps toward disabling the interface, potentially ending support for an architecture experiment introduced more than 14 years ago.

The latest proposal comes from Sebastian Andrzej Siewior, a Linux kernel developer at Linutronix who has been working on the removal effort throughout 2026. Rather than immediately deleting every component associated with x32, the proposed approach would first prevent the feature from being enabled through normal kernel configuration. This would give remaining users and distribution maintainers an opportunity to respond before the underlying implementation is removed.

The effort reflects a broader challenge in Linux development: maintaining compatibility with older or rarely used technologies while keeping the kernel manageable, secure, and efficient. Although x32 offered theoretical performance and memory advantages, it never achieved widespread adoption. With conventional x86_64 software dominating modern Linux systems, developers are increasingly questioning whether the additional maintenance burden remains justified.

Understanding the Linux x32 ABI

The x32 ABI was introduced with Linux kernel 3.4 in 2012 as an alternative to conventional 32-bit and 64-bit application environments. Its goal was to provide applications with access to the architectural improvements of x86_64 processors while retaining smaller data types and pointers associated with 32-bit software.

Traditional 32-bit x86 applications use the i386 ABI, which operates with a more limited register set and 32-bit execution conventions. Standard x86_64 applications, meanwhile, benefit from additional general-purpose registers, wider registers, and modern calling conventions, but they normally use 64-bit pointers. Those larger pointers can increase memory consumption in applications that maintain large numbers of pointer-heavy data structures.

The x32 ABI attempted to offer a compromise. Applications would execute using the x86_64 instruction set and its larger register file while retaining 32-bit integers, long values, and pointers. This programming model is commonly described as ILP32, meaning that integers, long integers, and pointers are all 32 bits wide.

The distinction can be illustrated by comparing the expected sizes of common C data types:

Google is exploring a new approach to Linux kernel security that could significantly change how device drivers interact with the operating system. The experimental project, known as Kage, uses compiler-based sandboxing to isolate drivers inside the kernel, potentially limiting the damage caused by memory corruption, programming errors, and exploitable vulnerabilities without requiring drivers to run as separate user-space processes.

The research was presented at the Linux Plumbers Conference 2026, held October 5–7, with Stanford University and Google researcher Zachary Yedidia discussing how LLVM’s Lightweight Fault Isolation (LFI) technology can create restricted execution environments for native kernel code. Unlike conventional isolation techniques, which often depend on separate processes or virtual machines, Kage attempts to preserve the performance advantages of kernel-space execution while reducing the amount of memory individual drivers can access.

Early prototypes have already demonstrated the concept using NVMe storage, networking, and Wi-Fi drivers. However, Kage remains an experimental research project rather than a feature available in mainstream Linux distributions. Its developers are still investigating performance, hardware access, and compatibility with more complicated drivers, including graphics hardware.

Why Device Drivers Remain a Major Linux Security Challenge

Linux device drivers are responsible for connecting the operating system to hardware components, including graphics cards, network adapters, storage controllers, USB devices, and wireless chipsets. Most traditional Linux drivers execute in kernel space, giving them privileged access to system resources and the ability to interact directly with hardware. This architecture is one reason Linux can deliver high performance across such a broad range of devices, but it also creates a significant security challenge.

When an ordinary application encounters a memory error, the operating system can often terminate that process without affecting the rest of the system. Kernel drivers operate under different conditions. Because they typically share the kernel’s address space and privileges, an invalid memory access or exploitable vulnerability can affect unrelated kernel components, potentially resulting in a system crash, privilege escalation, or complete compromise of the operating system.

The challenge becomes more complicated when considering the enormous number of drivers supported by Linux. Some are maintained by large organizations with extensive testing infrastructure, while others receive contributions from smaller development teams or individual maintainers. Even carefully reviewed drivers can contain bugs, particularly when they interact with complicated hardware, asynchronous operations, and memory-management mechanisms.