rfc:drop_32bit_support

PHP RFC: Drop 32-bit Builds

Introduction

Historically, PHP has supported both 32-bit and 64-bit environments. However, the vast majority of production deployments now use 64-bit systems. Major operating systems and distributions have either already dropped support for 32-bit architectures or are in the process of doing so. Maintaining 32-bit compatibility incurs development, testing, and ongoing maintenance overhead.

Size Limit

32-bit environments have known limitations especially because PHP's int type being a platform-dependent signed integer. This restricts values to a range between -2,147,483,648 and 2,147,483,647. This constraint leads to several problems:

Year 2038 Problem

In PHP, UNIX timestamps are the number of seconds since 1970-01-01 UTC stored in a signed integer, which results in a valid range of 1901-12-13 20:45:52 UTC to 2038-01-19 03:14:07 UTC.

Knowing the correct current time is essential in many programming patterns including ...

  • Time-based caching
  • Timeout handling
  • Auditing and logging
  • Token Expiration (e.g. JWT exp field)

The following extensions / API functions are effected ...

The only exceptions are:

  • DateTime / DateTimeImmutable classes, which internally uses int64_t. However, using this as a workaround is risky and error-prone, especially since timestamp-related methods (e.g., DateTimeInterface::[get|set]Timestamp()) are using PHP's signed integer type.
  • IntlCalendar class, which is using floating point numbers in milliseconds.

File Size Limit

On 32-bit builds, PHP can handle files up-to 2g only. This includes file streams as well.

Memory Size Limit

On 32-bit builds, the PHP process is limited to 2g memory.

Other Problems

  • crc32(): On 32-bit systems, many checksum results appear as negative integers. On 64-bit systems, all results are positive.
  • ip2long()/long2ip(): many IP addresses will result in negative integers on 32-bit environments.

OS and Platform Support Status

Most major platforms and Linux distributions have already ended support for 32-bit installations, though some still allow building and running 32-bit applications on 64-bit kernels.

Distribution 32-bit Support Status
--------------------------- ------------------------------------------------------------------------------------
Ubuntu Dropped official 32-bit kernel and install media as of 19.10
Debian Dropped official 32-bit kernel and install media as of Debian 12 (Trixie)
Fedora Dropped official 32-bit kernel and install media as of Fedora 31
Arch Linux Dropped i686 support in 2017
openSUSE Dropped 32-bit builds in Leap and Tumbleweed (Leap 15+ only supports 64-bit)
RHEL/CentOS/AlmaLinux/Rocky RHEL 7 was the last version to support 32-bit; all current releases are 64-bit only
Windows Dropped support for 32-bit systems as of Windows 11
macOS Dropped all 32-bit app support as of Catalina (10.15)
Apple Silicon 64-bit ARM only — cannot run 32-bit code at all

Proposal

Deprecate 32-bit support in the next minor release (PHP 8.x). Completely drop 32-bit support in the next major release (PHP 9.0).

Starting with PHP 9.0, it will no longer be possible to build or run PHP on 32-bit environments.

Backward Incompatible Changes

Beginning with PHP 9.0, PHP will no longer support 32-bit builds. Attempting to compile or run PHP in such environments will fail.

Proposed PHP Version(s)

  • PHP 8.x: Deprecate 32-bit support. Optionally warn users through deprecation notices.
  • PHP 9.0: Fully remove support for 32-bit environments.

RFC Impact

This RFC makes it impossible to build or run PHP on 32-bit-only platforms starting with PHP 9.0.

Also, it will not be possible to build PHP with 32-bit on 64-bit kernels.

Open Issues

Is it enough to inform users about this deprecation in the documentation or should the next minor release explicitly emit deprecation warnings when running or building on 32-bit builds?

Unaffected PHP Functionality

64-bit builds will remain fully supported and unaffected by this change.

Future Scope

This section details areas where the feature might be improved in future, but that are not currently proposed in this RFC.

Proposed Voting Choices

This requires a 2/3 majority. It is straight Yes/No vote to accepting the RFC.

Patches and Tests

PR to deprecate 32bit builds of PHP : https://github.com/php/php-src/pull/18876

Implementation

After the project is implemented, this section should contain

  1. the version(s) it was merged into
  2. a link to the git commit(s)
  3. a link to the PHP manual entry for the feature
  4. a link to the language specification section (if any)

References

Rejected Features

Keep this updated with features that were discussed on the mail lists.

rfc/drop_32bit_support.txt · Last modified: by mabe