Why won't Mountain Lion run on some MacBook Pros?

pcaulfield

I have an older MacBook Pro and was looking forward to upgrading the OS to Mountain Lion. I was at the local Apple store last week and while talking to one of the staff, I was told that there was a chance Mountain Lion wouldn't work with my MacBook, but she couldn't give me a clear answer as to why. I though that the main limitation was that since Mountain Lion is 64 bit, you just needed a Core 2 or later 64 bit processor. Well, my Mac is 64 bit and would seem to meet that requirement. What would keep Mountain Lion from running on some 64 bit Macs and not others?

Answer this Question

Answers

3 total
bcastle
Vote Up (22)

I agree.  Some of the early 64-bit Macs sometimes have 32-bit graphics drivers and that is causing the compatibility issue.  If you can figure out whether you have a 32-bit or 64-bit EFI, you should be able to tell whether you are good to go or not.  This is the command to run in Terminal that will tell you - if it returns "EFI32" you will have a problem running Mountain Lion:  ioreg -l -p IODeviceTree | grep firmware-abi

jimlynch
Vote Up (19)

Here's an article that might contain some answers for you.

Confirmed: Mountain Lion sends some 64-bit Macs gently into that good night
http://arstechnica.com/apple/2012/07/confirmed-mountain-lion-sends-some-...

"Apple declined to tell us the reasoning behind leaving some of these models out of potential Mountain Lion upgrades, but we suspected it is related to an updated graphics architecture that is designed to improve OS X's graphics subsystem going forward. Our own Andrew Cunningham suspects the issue is more specifically related to graphics drivers, since the GPUs not supported under Mountain Lion have drivers that were written before 64-bit support was common.

Information included with the first Mountain Lion GM now corroborates the connection to 32-bit graphics drivers as the culprit. While Mountain Lion is compatible with any Mac capable of running a 64-bit kernel, the kernel does not support loading 32-bit kernel extensions (KEXTs). Furthermore, Macs with older EFI versions that are not 64-bit clean won't load Mountain Lion's 64-bit only kernel.

As you might have already guessed, graphics drivers are KEXTs under OS X. And the GPUs in some of those early 64-bit Macs were deprecated before 64-bit KEXTs became common. Since those older drivers are 32-bit, Mountain Lion won't load them. We believe Apple decided it was better to draw the line in the sand for some older machines rather than invest the resources into updating the drivers for these older GPUs."

Lansing_22
Vote Up (14)

I have a 2007 MacBook. The old plastic white one and I am currently running Mountain Lion. As far as I can tell its all about the hard drive in the older models. I recently replaced the one in my 2007 with a 1TB and not only does Mountain Lion work, it now reads as a late model 2009 in the "about this Mac" section. I upgraded the ram too but I doubt that has anything to do with it. Even if you replace your current hard drive with the same size, just newer, that should do you. Hope this helps.

Ask a question

Join Now or Sign In to ask a question.
Microsoft issued invitations on Monday for a Sept. 30 event where it will unveil the next version of Windows, according to multiple online reports.
Microsoft's digital assistant, Cortana, is a mainstay of Windows Phone. For Windows 9, however, she'll be "just" an app.
A couple more Windows Phone features are apparently headed to Windows 9, with signs of Wi-Fi Sense and Storage Sense showing up in the latest leaked preview builds.
The new Windows is coming, and it looks a lot more like Windows.
Linux Mint 17 offers long-term support; emerges as open source alternative for Windows XP users.
A free Windows 9 'Threshold' would allow Microsoft to push more than half of all Windows 8 users to the upgrade within months, share data shows.
Apple's not-yet-shipped OS X Yosemite has gotten a jump on grabbing users, thanks to the company's free beta program, data released Monday showed.
iOS 8 has several features that business users will love and use. Here are the ones to look forward to the most.
You don't need an electrical engineering degree to build a robot army. With the $35 Raspberry Pi B+, you can create robots and connected devices on the cheap, with little more than an Internet connection and a bunch of spare time.
Join us:
Facebook

Twitter

Pinterest

Tumblr

LinkedIn

Google+

randomness