PHP: rfc:drop_32bit_support

This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong.
====== PHP RFC: Drop 32-bit Builds ======
  * Version: 0.9
  * Date: 2025-06-18
  * Author: Marc Bennewitz, marc@mabe.berlin
  * Status: Draft
  * First Published at: https://wiki.php.net/rfc/drop_32bit_support

===== 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 maintaining 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 defined as signed integers and used very often all over the place resulting in a limited range of ''1901-12-13 20:45:52 UTC'' to ''2038-01-19 03:14:07 UTC''.

The only exception is the ''DateTime[Immutable]'' class, which internally uses ''int64_t'', which avoids this issue.
However, using them as a workaround is risky and error-prone, especially since not all timestamp-related methods (e.g., [[https://www.php.net/manual/en/datetime.gettimestamp.php|DateTimeInterface::[get|set]Timestamp()]]) support full 64-bit behavior on 32-bit builds.

Additionally, other extensions rely on the UNIX timestamps as well and as such will be not fully functional (e.g. timestamps in [[https://www.php.net/opcache-get-status|opcache_get_status()]]).

=== 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. Even on 32-bit builds on 64-bit systems resulting in ''mmap() failed: Cannot allocate memory'' + OOM Error.

=== Internal Bitfield Exhaustion ===

Internals like opcodes, flag fields, and handlers are constrained by 32-bit word sizes, making certain optimizations or future extensions infeasible or hacky.

=== Other Problems ===

  * [[https://www.php.net/crc32|crc32()]]: On 32-bit systems, many checksum results appear as negative integers. On 64-bit systems, all results are positive.
  * [[https://www.php.net/ip2long|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 =====
Links to any external patches and tests go here.

If there is no patch, make it clear who will create a patch, or whether a volunteer to help with implementation is needed.

Make it clear if the patch is intended to be the final patch, or is just a prototype.

For changes affecting the core language, you should also provide a patch for the language specification.

===== Implementation =====
After the project is implemented, this section should contain 
  - the version(s) it was merged into
  - a link to the git commit(s)
  - a link to the PHP manual entry for the feature
  - a link to the language specification section (if any)

===== References =====
Links to external references, discussions or RFCs

===== Rejected Features =====
Keep this updated with features that were discussed on the mail lists.
Page Tools
