32bitonly

32bitonly is a term used in software development and distribution to indicate that a program, library, or firmware is built and intended to run only on 32-bit architectures. Software labeled 32bitonly does not provide native 64-bit binaries, and may rely on 32-bit data models, calling conventions, and libraries. The label appears in release notes, packaging metadata, and project documentation.

In the evolution from 32-bit to 64-bit computing, many projects eventually dropped 32-bit support. Some applications, especially legacy or resource-constrained ones, remain 32bitonly to support older hardware or embedded devices. On modern systems, 32-bit binaries can often be executed via compatibility layers or multiarch support, but nativity of 32-bit builds remains a barrier to portability.

Technical implications include the use of a 32-bit address space (in architectures like x86 and ARMv7), potential dependencies on 32-bit libraries, and differences in ABI. Packaging with a 32bitonly flag helps users identify that no 64-bit counterpart exists, guiding installation decisions on 64-bit systems.

Examples of usage include legacy Linux distributions maintaining i386 packages, or embedded firmware whose toolchains were never ported to 64-bit. The term is descriptive rather than a formal standard, and its exact meaning can vary by project.

See also 64-bit, IA-32, x86-64, multilib, compatibility layer.