OpenCore - Giving vintage Macs a whole new life

OpenCore has been around for a while - the core of most of the different versions around now are from this GitHub repo, which was uploaded in 2019. Lots of different packages and extensions end up bundled with OpenCore (Lilu, WhateverGreen, dozens of patches for all kinds of Macs) but they're all really built off of the same platform and are attemtping to do the same thing - make older Macs more useable and provide an experience as close to new as possible.

What OpenCore does isn't magic. In fact given that the whole project is maintained by volunteers, most of whom have full time jobs anyway, it would probably be something that a software company (dare I say even a computer manufacturer) could accomplish with only one or two paid staff. It's an amalgamation of small software patches and kernel extensions that solve bugs or other incompatibilities brought about by Apple's changes to each version of macOS. Does the newest version not include the drivers for an older Mac's keyboard/WiFi/webcam? OpenCore adds those files back in. Does the new macOS version expect that the computer its running on has access to the Metal graphics API? OpenCore patches the system to allow for other graphics APIs to run instead. Does the new macOS version include your Mac in it's Blacklist of systems it won't install on? OpenCore sidesteps the check to let the installer run.

It might seem that running an 'unsupported' version on older hardware is risky, but an operating systems isn't a black box that can't be understood. It's software just like any other, and any bugs can be solved just like with anything else. Microsoft of course is fine with this - have an old Pentium PC from 2004? Sure, try installing Windows 10, it'll probably work. The things that won't work (the speakers, the WiFi, the trackpad), well that's just because the makers of those parts haven't written drivers for Windows 10 yet. If you get those drivers, everything works great! That's the role OpenCore plays - it takes the place of the 'hardware manufacturer' (Apple) and writes bits of code or firmware to make sure it all works.

What about OS features, like Sidecar, or Stage Manager? Well again, like Windows, the OS doesn't really care what hardware its running on. It will run as well as it can, with the provided power of the CPU and GPU. If however, the software provider blacklists certain devices and prevents a feature from operating just because of the name of the device, then that's just an arbitrary lock.

This is how OpenCore works. It patches incompatibilities, re-adds drivers or kexts for older hardware to operate again, and can even remove arbitrary blacklists to enable features that can run perfectly well otherwise. It can also enable the system to phone-home to Apple and request regular software updates like security patches, and Apple will helpfully provide them just like if it was running on a newer system!

But there are a lot of different ways to get OpenCore running. You could grab it from the source GitHub repo and get it going from scratch, find a build of someone else's and try using that, or use something like OpenCore Legacy Patcher to create a bespoke installation for the hardware of your choice. Which is best?

The first 'distribution' of OpenCore I used was for the classic Mac Pro. Martin Lo on macrumors posted in a thread that was focussed on graphics acceleration, but now that single post has become practiclly the epicentre for all Mac Pro users trying to update their 5,1's past 10.14 Mojave and onto versions like Big Sur, Monterey and Ventura. All of which run absolutely flawlessly on Xeon and the beefy graphics cards that can run inside the full sized PCIe slots available in those machines. Martin Lo's package collates all the most asked-for features for Mac Pro users - GPU hardware accleration, support for the Thunderbolt PCIe cards and 256 Gigabytes of RAM (which is now more than any computer Apple offers now that the ARM-based Mac Pro tops out at 192GB). We use Martin Lo's package for our Mac Pros - it's the best option, and battle tested by hundreds of power users.

The problem comes of course if you try to use Martin's package on any other Mac. The patches that the Pro needs are completely different to what a Macbook need, or an iMac, or even a model from the same range but one year older (or newer). That's why Legacy Patcher shines. It's a program that utilises a database of all the various Mac models, and which patches and modifications that each one needs to run new macOS versions to their best potential. Every Mac is different, with different hardware and quirks of working, and Legacy Patcher will build exactly what each one needs. Tools made by a community of volunteers accomplish great things! If only manufacturers decided to do similar...