PHP RFC: Drop 32-bit Builds

• Version: 0.9
• Date: 2025-06-18
• Author: Marc Bennewitz, marc@mabe.berlin
• Status: Under Discussion
• First Published at: https://wiki.php.net/rfc/drop_32bit_support

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.

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:

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 ...

• date/time extension
  • most basic functions are effected like date() and time()
• calendar extension
• opcache_get_status()
• file time related functions
  • fileatime()
  • filectime()
  • filemtime()
  • stat()
  • lstat()
  • fstat()
  • touch()
  • getlastmod()
  • SplFileInfo::getATime() / SplFileInfo::getCTime() / SplFileInfo::getMTime()
    • PharFileInfo extends SplFileInfo
  • ZipArchive::setMtimeIndex()
  • ZipArchive::setMtimeName()
• memcache / memcached expiration time handling https://www.php.net/manual/en/memcached.expiration.php

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.

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

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

• 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.

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.

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.

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

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

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.

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?

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

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

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

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

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)

ML Year 2028 issue : https://discourse.thephp.foundation/t/php-dev-year-2038-issue/1904

ML Discussion : https://discourse.thephp.foundation/t/php-dev-rfc-drop-support-for-32bit-builds/1919

ML Vote : TBD

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