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: