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Apple Silicon#

Starting with certain models introduced in late 2020, Apple began the transition from Intel processors to Apple silicon in Mac computers.

Software is created with specific hardware in mind. In the past, software was made for Macs with Intel processors, which use the x86 instruction set. Now, software needs to be created for both Intel and Apple silicon (which uses the ARM instruction set) in order for the software to work efficiently and properly for each platform.

Rosetta#

For some apps that aren’t re-made for Apple’s silicon, Apple's Rosetta2 software will take apps made for Intel processors and translate them to run on Apple’s own ARM-based processors.

Install Rosetta 2

softwareupdate --install-rosetta --agree-to-license

In addition to configuring Homebrew for M1, add a second Homebrew installation for the x86_64 architecture.

arch -x86_64 /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

By default, simply use the brew command when installing any brew packages, but add an alias to your startup files for the x86 version of Homebrew, such as the following. This will allow you to easily install dependencies that are only supported on the x86_64 architecture. You can add the following line to your ~/.zshrc or similar file:

alias xbrew="arch -x86_64 /usr/local/bin/brew"

Python#

One of the largest incompatibilities for Python and Apple Silicon machines is the availability of wheels for compiled packages. Compiled packages are typically python modules with components written in other programming languages: like numpy, pandas, pytorch, etc.

When maintainers upload a compiled package to PyPI they also will typically upload compiled wheel (binary) files which come with variants for your exact system: MacOS x ARM x Python 3.11. However for older versions of the packages and python versions it is common for these wheels to be missing for our MacOS x ARM machines.

To fix this issue of wheel compatibility of our systems we will use Rosetta to install and use an x86 version of Python instead. This way we can use x86 versions of the wheels for packages which can be much more widely available.

dotfiles

If you're using the dotfiles from this project, this process can be streamlined as long as you have the x86 version of Homebrew installed (described above). The xbrew and xpython aliases are already included in the dotfiles - and there is an XBrewfile in the macos directory that can be used to install all the current Python versions:

xbrew bundle --file ~/.dotfiles/macos/XBrewfile
xpython3.8 -m venv .venv
source .venv/bin/activate

  1. Install your base x86 Version of Python

    • The example above is for Python 3.8 but it’s good to have one installed for all major versions.
    xbrew install "[email protected]"

  2. Create a Virtual Environment in your repository’s .venv directory using that x86 Python

    "$(xbrew --prefix [email protected])/bin/python3.8" -m venv .venv

  3. Activate the x86 Python Virtual Environment you just created.

    source .venv/bin/activate

  4. Install any tools or requirements you might need

    • Using x86 python versions to run tools like tox, which creates its own virtual environments, can be especially important as the underlying virtual environments managed by these tools will also be x86
    python -m pip install "tox<4"
python -m tox