64bit Not Enabled on Mac OSX Snow Leopard by Default

[Scorbing]

READ THIS

So if this is the case, then a Mac with 4GB of RAM is not using it's full memory capacity?

I am new at macs so can someone please explain. I still didn't understand the article much.

[zeta_immersion]

yes, you need to tell it to boot into 64bit kernel otherwise it defaults to 32bit ...

i read this here but in another thread ... what you need to do, is to look in your app folder and see if the programs you have will work fine in a 64bit environment ... and if so then make the switch (assuming you have >3gb ram and you want to utilize the entire amount)

[Guest]

So if this is the case, then a Mac with 4GB of RAM is not using it's full memory capacity?

It doesn't matter if its booting into the 32-bit kernal, you will still be able to use more than 3GB of RAM :). Apps that can run in 64-bit will do so.

Its different from the way Windows works :).

Edited November 22, 2009 by Guest

[richardsim7]

Yep, only Windows doesn't utilise the RAM in 32 bit mode ;)

-Rich-

[bobbba]

I thought the article you linked to explained it pretty well.

Mac OS X is not Windows, so the rules regarding 32bit/64bit are not the same. Apple chose a different strategy to MS to switch to 64bit. Apple have one OS version that features both 32bit and 64bit. The results are that Mac users are still not using 100% 64bit software just like Windows users aren't. Not having a 64bit kernel enabled has no bearing on your apps and the OS components which are true 64bit. The full 4GB will be used fully by the applications that you run regardless of the kernel.

[drshdw]

32bit boot up is for third party compatibility for drivers, etc. It still runs 64bit apps and utilizes 4GB+ just fine.

[hdood]

Not having a 64bit kernel enabled has no bearing on your apps and the OS components which are true 64bit. The full 4GB will be used fully by the applications that you run regardless of the kernel.

Only 64-bit though. 32-bit applications can only use 3GB automatically, as that is the size of the virtual address space. Same issue as on Windows.

[MasterC]

Yep, only Windows doesn't utilise the RAM in 32 bit mode ;)

-Rich-

Exactly my Mac Pro starts in 32bit, and I can use all 10GB of RAM I have. (Y)

[Rudy]

Exactly my Mac Pro starts in 32bit, and I can use all 10GB of RAM I have. (Y)

remember that individual processes are limited to 4GB of ram each though

[Elliott]

remember that individual processes are limited to 4GB of ram each though

Only 32-bit processes are. 64-bit processes can expand as far as they want, even if the kernel starts in 32-bit.

[Julius Caro]

Even Leopard (OS X 10.5) was able to fully use those 4GB+ of ram...

[cupertinian]

Everything - except for iStat Menu's is listed as (64-bit) on my Mid-2009 MacBook Pro.

So I guess I'm running 64-bit?

[Elliott]

Everything - except for iStat Menu's is listed as (64-bit) on my Mid-2009 MacBook Pro.

So I guess I'm running 64-bit?

No, your kernel is probably running 32-bit (check kernel_task in Activity Monitor). However, most of the applications in Snow Leopard are 64-bit now, so they run in 64-bit even if your kernel is limited.