aarch64-variant-provider

This is a plugin for the proposed wheel variants implementation that provides properties specific to AArch64 CPUs.

Usage

Namespace: aarch64

Plugin API: aarch64_variant_provider (the default)

Example use in pyproject.toml:

[variant.providers.aarch64]
requires = ["aarch64-variant-provider"]

Provided properties

To obtain the full list of properties supported by a given plugin version, install it, then use:

variantlib plugins get-configs -a -n aarch64

To obtain the full list of properties compatible with your system, use:

variantlib plugins get-configs -s -n aarch64

aarch64 :: version

Values: 8.1a, 8.2a...

Specifies the targeted microarchitecture version. The plugin automatically adds appropriate -march= value to CFLAGS. The resulting wheel will be incompatible with CPUs below the specified microarchitecture version.

Please note that many extensions (such as SVE) are technically optional for multiple microarchitecture versions, so this optional may have limited usefulness.

aarch64 :: <extension>

Feature names: asimdhp, sha3, sve...

Values: on

Specifies that the built wheel uses the specific CPU extension. The plugin does not emit any compiler flags at the moment. The resulting wheel will be incompatible with CPUs that do not implement the specific extension.

These properties should only be used when the relevant intrinsics are used unconditionally. If the code using them uses runtime detection, they should not be specified, as they will prevent installing the wheel on systems where the extension is not available (yet the code would work fine, disabling the code in question).

Detection

Detection is backed by archspec and shared between provider-variant-x86-64 and aarch64-variant-provider. The output from each command is mapped against the archspec microarchitecture database to emit the actual feature.

OS	Detection method
Linux	Read CPU implementer, CPU part, and Features from the first CPU entry in /proc/cpuinfo. The part number narrows the matching models when a compatible match exists.
macOS	Run sysctl in a subprocess, read machdep.cpu.brand_string, and infer features from the database’s Apple model entries.
Windows	Not implemented, instead it returns a generic Armv8-A baseline 8a baseline (aarch64 :: version :: 8a).