OS X 10.8 (Mountain Lion) Won't Support 64-bit Macs with Older GPUs

Apple is pitching Mac OS X 10.8 (Mountain Lion) as the cat's meow with over 200 new features "that add up to an amazing Mac experience," but that only applies if you're rocking a compatible system. Some older Mac models, including ones that are 64-bit capable, aren't invited to the Mountain Lion party, and it's likely because of the GPU. First, let's look at which Mac models made the cut:
  • iMac (Mid 2007 or newer)
  • MacBook (Late 2008 Aluminum, or Early 2009 or newer)
  • MacBook Pro (Mid/Late 2007 or newer)
  • MacBook Air (Late 2008 or newer)
  • Mac Mini (Early 2009 or newer)
  • Mac Pro (Early 2008 or newer)
  • Xserver (Early 2009)

Apple Mac Systems

That covers all the recent systems, but for ones that are slightly older, it's being reported (unofficially) that an updated graphics architecture intended to smooth out performance in OS X's graphics subsystem is the underlying issue. It's no coincidence, then, that the unsupported GPUs happen to be ones that were fairly common back before 64-bit support became mainstream.

Mountain Lion apparently doesn't play nice with 32-bit GPU drivers, and while Apple could spend time and resources bringing older models up to par, the Cupertino company decided it was better off dropping support altogether. That's a tough pill to swallow for owners of Mac systems that are barely more than three years old.

Via:  Arstechnica
renderpipeline 2 years ago

There is not just the 32bit / 64bit driver issue. All Macs with a OpenGL 3.2 capable GPU will support 10.8 and no older machine. This might give Apple the advantage to ditch legacy OpenGL e.g. in there window manager (for there own apps and OS, not talking about removing 2.1 support for 3rd party apps!).

robogobo 2 years ago

Well, that reasoning applies to everything but the Mac Pro 1,1 and 2,1 which can easily support video cards running OpenGL 3.2. Still no reason to cut them off categorically.

HAliquis 2 years ago

It's Apple. They drop support frequently after a few versions. Nothing new here move along.

douglas_goodall 2 years ago

[quote user="robogobo"]

Well, that reasoning applies to everything but the Mac Pro 1,1 and 2,1 which can easily support video cards running OpenGL 3.2. Still no reason to cut them off categorically.


After some research, I discovered that the issue starts with the EFI ROM which in my machine (Mac Pro 2,1) is a 32-Bit EFI.

Because of this, my existing operating system, Lion could not load the 64-bit kernel, but could load the 32-bit kernel.

It appears the Mountain Lion OS does not have a 32-bit kernel, and therefore cannot load at all on machines with 32-bit EFI.

This 32-bit EFI ROM also means you cannot load Windows 7 64-bit version either, just the 32-bit version.

Apparently had I waited a few months to order the 8-core machine, it would have come with the newer 64-bit EFI ROM and I would not have to deal with these limitations.

I find it disturbing that Apple sold me an 8-core Xeon machine that couldn't load a 64-bit OS. What were they thinking. I spent seven thousand dollars on that machine with the expectation that I wouldn't outgrow it very soon.

The machine in all other respects should be highly upgradable, given the easy-pull CPU modules and such. I might have even considered buying a new motherboard if that was an option.

So the bottom line is that my super-machine will shortly have a down-level operating system, and applications written specifically for Mountain Lion will probably not run due to environmental dependence.

To the extent that I primarily write transportable code in GNU c++ and I can still do that with this machine for a while. However when Apple decides to no longer provide security updates, it will become more dangerous to use programs such as Safari that reach out beyond my firewall.


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