Install OS X Mountain Lion Developer Preview on Old Unsupported Macs
If you read the OS X Mountain Lion system requirements and got discouraged that the next version of OS X won’t support your computer, don’t give up hope for that old Mac quite yet!
A crafty MacRumors Forums member has managed to get OS X Mountain Lion Developer Preview working on an officially unsupported mid-2007 white MacBook, a model with the unsupported Intel GMA 950 GPU, 2GHz Core 2 Duo CPU, and just 1GB of RAM. Not only does OS X 10.8 run on the old MacBook, it reportedly works very well and with full graphics acceleration.
The method has reportedly been tested on MacBook 2007 MacBook2,1 and MacBook 2008 MacBook3,1 but presumably will work on other unsupported Macs as well. If you want to try this yourself, be prepared to get your hands dirty, and backup your Mac before beginning. You’ll need access to the Dev Preview, an officially supported Mac in addition to the unsupported Mac to copy some files over, the guide calls for switching hard drives but you could do the same with target disk mode. Regardless, you’ll need a fair amount of patience.
Here are the full instructions according to hackerwayne on MacRumors forums:
1. Get a copy of Mountain Lion, I got mine from Apple. If you’re not a dev, maybe you can get it at “the bay full of pirates”
2. Make sure you have a Mountain Lion compatible Mac, Im using a MacBook 2.4GHz Aluminum 2008
3. I have no FireWire to do target disk mode, so i removed the HDD from the MacBook White, pop it into the ML compatible Mac and install Mountain Lion like normal.
4. Get everything set up, until you reach the desktop
5. Now, remove the HDD from the compatible Mac, pop it into the MacBook White. Restart the MB White and hold down “CMD + V”. It should say “Incompatible Mac detected. Reason: Mac-F4208EC8” the “Mac-F4208EC8” is a unique ID for your Mac, so copy that down.
6. Remove the HDD from the MacBook White, and again, pop it into the compatible Mac, reboot back into Mountain Lion. U Now, navigate to ‘/System/Library/CoreServices’ on the Mountain Lion partition. Unlike 10.7 Lion, users delete PlatformSupport.plist. In ML 10.8 add that unique ID that you copied just now to PlatformSupport.plist. If you try to delete that Plist file, a Kernal panic will greet you during boot.
7. In PlatformSupport.plist, remember to add your model identifier, if you are using a MacBook White like me, add MacBook2,1 right above MacBook6,1. This step is important as the EFI reads this by sequence.
For MacBook 07 and 08 add this line right above MacBook6,1
For 07: MacBook2,1
For 08: MacBook3,1
For Mac Pro 06 and 07 add this line right above MacPro4,1
For 06: MacPro1,1
For 07: MacPro2,1
8. Now, boot it back using the MacBook White and confirm that the ML is booting. If you did everything right, you should be able to reach the desktop, but have no accelerated graphics whatsoever, only framebuffer. (for MacPro1,1 and 2,1 with upgraded graphics card, you should get a perfectly working ML)
9. 2 ways to perform this step:
a) Manually copy and install the right kext.
b) Use kexthelper (skip 10 – 13)
MacBook2,1 - AppleIntelGMA950.kext, AppleIntelGMA950VADriver.bundle, AppleIntelGMA950VLDriver.bundle
MacBook3,1 - AppleIntelGMAX3100.kext, AppleIntelGMAX3100VADriver.bundle, AppleIntelGMAX3100FB.kext, AppleIntelGMAX3100VLDriver.bundle
MacPro1,1/2,1 - upgrade graphics card to GT210 or HD 5770 No kext required. 7300GT untested!
MacMini2,1;3,1 iMac4,1;5,1 untested. Please try using above method depending on which graphics card you have and report back results! Thanks!
For ATI graphics card, i do not have a Mac to test them, I believe its the same, try ATIRadeonX1000.kext, ATIRadeonX1000GL.bundle, ATIRadeonX1000VA.bundle, ATI- yliadxos.bundle and report back.
10. Back to the MB white, install the kext using KextHelper and reboot.
11. After it reboots, you should be able to see a pop up message saying that the kext isnt compatible. If yes, reboot.
12. Boot into Single User Mode (Command+S ) and type the following:
chmod -R 755/Volumes/~MLPartitionName/System/Library/Extensions/AppleIntelGMA950.kext
chown -R root:wheel /Volumes/~MLPartitionName/System/Library/Extensions/AppleIntelGMA950.kext
Then remove cache and rebuilt:
rm -rf /Volumes/~MLPartitionName/System/Library/Extensions.mkext
kextcache -k /Volumes/~MLPartitionName/System/Library/Extensions
14. Working Mountain Lion on not supported system.
The whole process is pretty similar to getting a Hackintosh running on unsupported Mac hardware, and assuming Apple doesn’t change anything it could be theoretically possible for custom third party OS X 10.8 installers to be created down the road specifically for the unsupported Macs. Maybe even with an easy USB installer? Who knows, but it’s also possible that Apple will bring support to these Macs in the final OS X Mountain Lion build, and it’s equally as possible that the next Developer Preview build will remove the ability for the above method to work at all. Ultimately we just won’t know until OS X 10.8 is finalized from Apple.
We don’t have a Mac to test this with, so if you run into any problems the best place to troubleshoot is probably the origin Forums thread on the matter at MacRumors.com.
If you try this, let us know! yliadxos
Update: Have a Mac Pro instead? Here’s a guide on how to install it on Mac Pro 1,1 and Mac Pro 2,1