How to check if Python is running on an M1 mac, even under Rosetta?

Question

I have python 3.10 code that launches a process but it needs to run a different process if it is running on an M1 Mac.

Is there a way to reliably detect if you are on an M1 Mac even if the python process is running in Rosetta?

I've tried this:

print(sys.platform)

# On Intel silicon:
darwin

# On M1 silicon:
darwin

but it always prints "darwin".

I tried sniffing around in the os.* and sys.* libraries and the best I found was this:

print(os.uname())

# On Intel silicon:
posix.uname_result(sysname='Darwin', nodename='XXX', release='21.5.0', version='Darwin Kernel Version 21.5.0: Tue Apr 26 21:08:22 PDT 2022; root:xnu-8020.121.3~4/RELEASE_X86_64', machine='x86_64')

# On M1 silicon:
posix.uname_result(sysname='Darwin', nodename='XXX', release='21.4.0', version='Darwin Kernel Version 21.4.0: Fri Mar 18 00:47:26 PDT 2022; root:xnu-8020.101.4~15/RELEASE_ARM64_T8101', machine='x86_64')

I assume it returns machine= 'x86_64' on the M1 machine because Python is running in Rosetta? The version field does appear different:

# Intel
version='Darwin Kernel Version 21.5.0: Tue Apr 26 21:08:22 PDT 2022; root:xnu-8020.121.3~4/RELEASE_X86_64'

# M1
version='Darwin Kernel Version 21.4.0: Fri Mar 18 00:47:26 PDT 2022; root:xnu-8020.101.4~15/RELEASE_ARM64_T8101'

Is parsing uname() and looking for "ARM" in the version field the best way to check for M1 silicon if you are running under Rosetta?

Sitton

What about platform.processor() ? Which gives me arm on M1 (haven't checked using Rosetta) – Grizzled

Answer 1

Use Python's built-in platform library to determine if a Mac is M1/M2:

import platform

print(platform.processor())

On an M1/M2 Mac --> arm

On an older Mac --> i386

Gorgon

i386 build of Python running on m1 reports i386 for me – Jagatai

This is wrong. I am on an M1 mac and platform.processor() returns i386. – Repel

But doesn't i386 return value just mean that you are running python through rosetta emulation on your M1 cpu? My M1 reports arm just as this post describes. – Intrauterine

Here's how I tested it: On my 2015 Intel MacBook Pro, I installed Python, and platform.processor() returned i386. On my 2022 M2 MacBook Pro, I installed Python, and platform.processor() returned arm. If that's what people are looking for, there it is. – Gorgon

Answer 2

The only way I was able to do it from Python was to call out to sysctl. This is taken from cmake-macos-rosetta:

Non-Rosetta Python on M1:

>>> import platform, subprocess
>>> platform.processor()
'arm'

# Rosetta would not report arm.

>>> subprocess.run(["sysctl", "-n", "sysctl.proc_translated"])
0

Rosetta Python on M1:

>>> import platform, subprocess
>>> platform.processor()
'i386'

# Rosetta fakes the processor.

>>> subprocess.run(["sysctl", "-n", "sysctl.proc_translated"])
1
CompletedProcess(args=['sysctl', '-n', 'sysctl.proc_translated'], returncode=0)

Birt

Answer 3

You could just check for the Processor Name, and check it that way. The easiest way to get it is by using the cpuinfo module. cpuinfo.get_cpu_info()['brand_raw'] returns a string with the processor brand and name, for example "Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz". If you only want to have "i5-6500", you can just take the 3rd word from the string.

import cpuinfo
cpudata = cpuinfo.get_cpu_info()['brand_raw']
cpuname = cpudata.split(" ")[1]

If you then would print(cpuname), it should only output the processor "name", so in this case i5-6500.

Atombomb