Installing Big Sur on a 2010 MacBook Air Core 2 Duo

Screenshot, macOS 11.6.5 running on Late 2010 MacBook Air

I have an old 1.86 GHz Core 2 Duo (Penryn, SL9400) “Late 2010” MacBook Air, with 4GB of RAM (fixed), the stock 128GB SSD, and GeForce 320M graphics. Officially, support for this machine stops at 2017’s MacOS 10.13 High Sierra. Unofficially, it runs macOS 11 Big Sur. Not without a few minor glitches, and it’s certainly not high performance, but it runs, and it runs well enough to run a web browser, watch videos on YouTube, edit documents in Microsoft Word or LibreOffice, etc.

Note that this method basically requires you to create the patched install media on the machine you’re going to be installing Big Sur onto, and the Big Sur createinstallmedia utility won’t run on anything older than High Sierra (AFAIK).

First I used the USB restore drive it came with to setup a 20GB partition for Snow Leopard. It’s the last MacOS version that can run PowerPC binaries through Rosetta, so it’s something to keep around.

I downloaded the 11.6.5 installer package from Apple using a link on Mr. Macintosh’s page. Running InstallAssistant.pkg created /Applications/Install macOS Big Sur.app. I used that to create an installer using a handy 32GB USB drive.

$ sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/UNTITLED

Once that was done, I used OpenCore Legacy Patcher 4.3 to setup the USB drive’s EFI partition suitably. The app (I used the TUI version) was smart enough to know this machine was pre-Metal and couldn’t have System Integrity Protection (SIP) or Secure Boot enabled. By default, the picker was enabled.

I used option 1 to Build OpenCore, then option 2 to Install OpenCore to USB/internal drive, in my case, disk2s1 was the EFI partition.

Rebooted holding down the option key, picked EFI Boot, then booted Install macOS Big Sur.

Several reboots (selecting macOS Big Sur Installer, or something like that - will update this when I do it again) later, I had a working Big Sur install. I used OpenCore Legacy Patcher TUI again to (option 1) Build OpenCore and then (option 2) install it to the EFI partition on the internal SSD, and finally (option __?__) Post Install Root Patch the system to support hardware acceleration on my decidedly non-Metal GeForce 320M GPU. I’ve noticed a bit of color-flickering in some dialog boxes and on the side bar in Finder windows, but overall, it runs very well.

The first time it boots up, it will take forever building a Spotlight database etc., and will be basically unusable. Once it settles in, however, I’ve found it usable for light general purpose computing, and expect to get another couple of years of useful life out of it before it gets recycled or turned into a Linux workstation.