Hi! You are obsolete now. Have a nice day!
A while ago I wrote about upgrading my 13-inch Aluminium Macbook (Late 2008) to Mavericks. This marvellous Mac has been supported by all releases of Apple's operating system for Macintosh computers since Mac OS X Tiger (10.4). Has it really? Well, with macOS Sierra
– Apple's latest incarnation of Mac OS X
– air is getting thin for Macs sold before 2009, although the core of the OS is not expected to have changed significantly from Mac OS X El Capitan (10.11). After reading about others having upgraded their officially unsupported Macs to macOS Sierra, I decided to grab my now obsolete Macbook and give it a go myself.
The Upgrade – How it's (going to be) done
I am going to tackle this as laid out below:
- Obtain the original macOS Sierra installer from Apple
- Modify installer to work with my officially unsupported but nevertheless adequate Mac
- Create a bootable usb pen drive or hard-drive with said installer
- Boot and install macOS Sierra from it
Lay Hands on the Installer
Luckily this is an easy one: since I have other Macs supported by macOS Sierra I already have downloaded the installer through the Apple App Store.
Tinkering Commences – Improved Support
Let's make the installer support more Macs. The application Install macOS Sierra
contains a disk image called InstallESD.dmg
which is stored away under Contents/SharedSupport. I mount this image which pops up as volume OS X Install ESD
: see, still ye good olde Mac OS X inside. On this volume I navigate to the Packages folder and copy InstallableMachines.plist to my Desktop for later editing. ioreg in Terminal helps me to find my Mac's board id:
$ ioreg -lp IOService | grep board-id
| "board-id" = <"Mac-F42D89C8">
I add a new string entry with my model’s board id Mac-F42D89C8
under SupportedBoardIds to my InstallableMachines.plist. That should do the trick.
Tinkering Continued – Image is nothing
After unmounting the original disk image I create a writeable disk image from it with Disk Utility
, which I then mount. I replace the image's original InstallableMachines.plist with my edited version and unmount the volume.
Now let us duplicate the entire Installer app on the Desktop and implant the new image (with the original file‘s name, of course). Now I should be able to create my own bootable usb pen drive with the installer on it. The command looks like this:
sudo ~/Desktop/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath ~/Desktop/Install\ macOS\ Sierra.apploading
Last-Minute Preparations
System Integrity Protection (SIP) needs to be disabled on the system one intends to install Sierra on. Which can be done by booting into the Macbook's 10.11 Recovery partition, opening Terminal, and running the command csrutil disable. SIP must remain disabled for as long as you run Sierra.