32-bit or 64-bit Apple Boot Screen

[MacMan]

Just to clarify. When choosing this option, does this acutaly force OSX to use 32-bit Mode or 64-bit Mode? Or is this boot screen used just for booting into OSX and then a mode is configured?
Thanks.

It sets the default kernel to boot. You can always override at boot time.

 

[MacMan]

Well what i am confused about is for instance, If i install a 5850HD and use the ATY_int i am foced to use 32-bit Apple Boot Screen (Ge=no) does this option force OSX to run in 32-bit mode? Or will it still run 64bit applications after booting with the above mentioned option?
Thanks.

No, it forces a 32-bit kernel just like 32-bit Apple Boot Screen.

There are experimental solutions to run the HD5850 in 64-bit mode. Once there is a stable solution we will provide a guide and an updated MultiBeast to go along with it.

 

[MacMan]

So i have to ask, why does the kernal have to be booted in 32bit but the os can run 64bit applications? (Ex. You cant run 64bit apps in say windows 32bit.)

Thanks MacMan, your the Bomb!

The reason is that ATY_Init kext is 32-bit only, once the alternative solutions are stable, we won't need to use it and can run a 64-bit kernel.

Anyway the only limitation of the 32-bit kernel is that any single application can only address 4GB of memory. Probably less than 1% of the Mac applications can do this.

 

[cybertron3000]

I set mine to 64-Bit Apple Boot Screen, the result is, that my hackintosh doesn#t boot. After Chimera the gray apple comes up and the litte wheel under it starts to spin. that is it. it spins till i manualy reset my computer.

what to do?

 

[ghorwith]

I set mine to 64-Bit Apple Boot Screen, the result is, that my hackintosh doesn#t boot. After Chimera the gray apple comes up and the litte wheel under it starts to spin. that is it. it spins till i manualy reset my computer.

what to do?

First, confirm that you can boot in 32-bit by using -v arch=i386 switch at boot (-v for verbose so you can what's happening, and arch=i386 to force the 32-bit kernel). If it boots ok, boot with just -v to see where it hangs. Most of the issues / solutions involve replacing IOPCIFAMILY.kext, IOUSBFAMILY.kext (these can be done from Multibeast), and / or AppleRTC.kext.

22Aug Update - The AppleRTC.kext was the culprit. After replacing this, I was able to go back to the IOPCIFAMILY and IOUSBFAMILY kexts that ship with Lion and it boots 64-bit with no problem.

 

[TheSmartGuy]

So i have to ask, why does the kernal have to be booted in 32bit but the os can run 64bit applications? (Ex. You cant run 64bit apps in say windows 32bit.)

Thanks MacMan, your the Bomb!

The reason is that ATY_Init kext is 32-bit only, once the alternative solutions are stable, we won't need to use it and can run a 64-bit kernel.

Anyway the only limitation of the 32-bit kernel is that any single application can only address 4GB of memory. Probably less than 1% of the Mac applications can do this.

Thanks for the info. I've only been able to boot into 32-bit on my Hackintosh (64-bit causes kernel panic), so I was confused as hell when my Hackintosh was still able to use my 8 GB of RAM. I don't do heavy video editing or whatever, so I guess the 4 GB limit for a single application isn't a problem.

 

[Going Bald]

Thanks for the info. I've only been able to boot into 32-bit on my Hackintosh (64-bit causes kernel panic), so I was confused as hell when my Hackintosh was still able to use my 8 GB of RAM. I don't do heavy video editing or whatever, so I guess the 4 GB limit for a single application isn't a problem.

32 bit kernel can see and use up to 128GB of ram. The restriction comes in with the apps - each app can only use 4GB for itself. So, to use all of your 128GB of ram, you would have to have 31 apps running at once using the max ram they were capable of using (=4GB each). I say 31 apps because the system needs a little and so the 32 app wouldn't get a full 4GB.
With the 64 bit kernel this restriction goes away and the ram amount goes way up. Each app, if written for 64 bit, will use as much as it needs of what you have available. Your limit then becomes how much ram your board can have installed.

 

[cowfodder]

Thanks for the info. I've only been able to boot into 32-bit on my Hackintosh (64-bit causes kernel panic), so I was confused as hell when my Hackintosh was still able to use my 8 GB of RAM. I don't do heavy video editing or whatever, so I guess the 4 GB limit for a single application isn't a problem.

32 bit kernel can see and use up to 128GB of ram. The restriction comes in with the apps - each app can only use 4GB for itself. So, to use all of your 128GB of ram, you would have to have 31 apps running at once using the max ram they were capable of using (=4GB each). I say 31 apps because the system needs a little and so the 32 app wouldn't get a full 4GB.
With the 64 bit kernel this restriction goes away and the ram amount goes way up. Each app, if written for 64 bit, will use as much as it needs of what you have available. Your limit then becomes how much ram your board can have installed.

That is one of the best explanations of OS X 32bit vs 64bit I've seen.

 

[lankemo]

Second that,
Thanks, that was a very well formed explanation.
There's next to no easy to read info about this on the web