Linked by moondevil on Wed 11th Jul 2012 22:49 UTC
Mac OS X Ars Technica is reporting that certain 64bit Mac models won't be able to run Mountain Lion. The problem is the graphic card drivers; these are still 32bit, and Apple is unwilling to update them to 64bit. A 64bit kernel can't load 32bit drivers, so that's that. Apple has a list of supported models on their Mountain Lion upgrade page, so you can easily check if your computer is capable of running Mountain Lion.
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RE[2]: No biggie
by lucas_maximus on Thu 12th Jul 2012 09:47 UTC in reply to "RE: No biggie"
lucas_maximus
Member since:
2009-08-18

It isn't kept secret, they simply don't support it.

Reply Parent Score: 1

RE[3]: No biggie
by phoudoin on Thu 12th Jul 2012 10:07 in reply to "RE[2]: No biggie"
phoudoin Member since:
2006-06-09

Not since Macs are intel machines, indeed.
Because they can't anymore.

But they were up to latest MacPro G5.

Reply Parent Score: 3

RE[4]: No biggie
by henderson101 on Thu 12th Jul 2012 11:34 in reply to "RE[3]: No biggie"
henderson101 Member since:
2006-05-30

Not since New World Macs too. The New World had no ROM in silicon and making them boot was just down to OpenFirmware and the right bootloader (of which there were several.)

Reply Parent Score: 2

RE[3]: No biggie
by Neolander on Thu 12th Jul 2012 13:13 in reply to "RE[2]: No biggie"
Neolander Member since:
2010-03-08

Well, it can be considered a secret, since what Apple calls "EFI" only remotely complies with the EFI and UEFI specs and keeps doing weird undocumented stuff (such as overwriting kernels after boot) all the time.

Here are some examples :
http://mjg59.livejournal.com/132477.html
http://mjg59.dreamwidth.org/12037.html

Reply Parent Score: 5

RE[4]: No biggie
by Alfman on Thu 12th Jul 2012 14:41 in reply to "RE[3]: No biggie"
Alfman Member since:
2011-01-28

Neolander,

Your links were a good read. The second one about the MAC boot process was eye-opening, wow are there a lot of dependencies. I'm not sure why apple would stray from a vanilla EFI implementation.

One parenthesised comment came up though and I think it's particularly relevant to a discussion of running 32/64bit OSes together.

"So then we have runtime services. EFI is, depending on how you want to look at it, either saner or much less sane than traditional BIOS access. The firmware gives you a bunch of function pointers and you then simply call them with native calling convention (this, incidentally, is why it's pretty much impossible to run a 32-bit OS on 64-bit EFI, or a 64-bit OS on a 64-bit system that happens to have 32-bit EFI)."

In theory, it shouldn't be too difficult to build a shim between 32bit and 64bit calling conventions. It might not be the most efficient solution, but I see no reason this shim couldn't be generated automatically from EFI function call prototypes.


A 64bit EFI should be able to handle zero padded 32bit OS pointers. The main question I have is whether the EFI data structures themselves change between 32bit and 64bit interfaces, because if they do then that rules out this simple trampoline approach.

Reply Parent Score: 4

RE[4]: No biggie
by lucas_maximus on Thu 12th Jul 2012 17:28 in reply to "RE[3]: No biggie"
lucas_maximus Member since:
2009-08-18

That is pretty shitty ... While I disagree with it I will have to point out when you buy an Apple Computer one buys it IMO for the integration between the hardware and the OS.

They support booting Windows because it is a common use case.

Reply Parent Score: 2

RE[4]: No biggie
by Delgarde on Fri 13th Jul 2012 00:13 in reply to "RE[3]: No biggie"
Delgarde Member since:
2008-08-19

Well, it can be considered a secret, since what Apple calls "EFI" only remotely complies with the EFI and UEFI specs and keeps doing weird undocumented stuff (such as overwriting kernels after boot) all the time.

Here are some examples :
http://mjg59.livejournal.com/132477.html
http://mjg59.dreamwidth.org/12037.html


To be fair, if you follow Matthew's posts, it's clear that *nobody* remotely complies with the standards.

Reply Parent Score: 2