64-bit Snow Leopard defaults to 32-bit kernel

[dexterboygenius]

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64-bit Snow Leopard defaults to 32-bit kernel

Apple's OS X 10.6 operating system Snow Leopard, released today, by default loads with a 32-bit kernel, despite running 64-bit applications.

While it ships with a number of 64-bit native applications, Apple's kernel itself defaults to 32-bit, unless the user holds down the "6" and "4" keys during boot time, at which point the 64-bit kernel is loaded. Only Apple's X-Serve products, using Snow Leopard Server, boot into a 64-bit kernel by default.

"For the most part, everything that they experience on the Mac, from the 64-bit point of view, the applications, the operating system, is all going to be 64-bit," Stuart Harris, software product marketing manager at Apple Australia said.

Harris said that at this stage there were very few things, such as device drivers, that required 64-bit mode at the kernel level but the option was available.There appears to be no way within the GUI to make this change permanent, requiring the editing of the com.apple.Boot.plist file to make the change — a text-based configuration file. Users have already released applications to address this issue.

This raises another problem — if equipped with 4GB RAM, those with a 32-bit EFI chip are not capable of making use of the full amount, our mid-2007 MacBook only showed 3GB available for system use through Activity Monitor despite having 4GB installed, not delivering the true 64-bit experience. Newer machines equipped with a 64-bit EFI chip running a 32-bit kernel seemed capable, with Activity Monitor reporting 3.75GB RAM available, as 256MB was put aside for the GeForce 9400M graphics chip.

It is unknown at this stage what sort of performance implications running 64-bit applications on a 32-bit kernel will have compared to a 64-bit kernel.While a large portion of the OS has been optimized and updated, some applications, such as DVD player, Front Row, Grapher and iTunes are still 32-bit only, and some extensions are still run as a Universal Binary, despite the PPC architecture no longer being supported.


Source: ZDnet News

[Ad1tya]

True for older gen Mac's.

Currect iMac's, Mac Pro's, Macbooks and Macbook Pro's load the 64-bit kernel.

[KiD0M4N]

Originally Posted by Ad1tya True for older gen Mac's. Currect iMac's, Mac Pro's, Macbooks and Macbook Pro's load the 64-bit kernel.

Sorry, thats incorrect.

My super recent MacBook Pro 'defaults' to the 32 bit kernel, but is capable of running 64 bit applications. Infact, all the default applications are 64 bit by default.

The 64 bit kernel would required 64 bit drivers (aka kexts).. which isn't a problem though.

You can switch over to 64 bit kernel by holding down '6' and '4' during bootup.

[Ad1tya]

^^ Oh ok. So do you do that?

Any compatibility issues?

[initpidzero]

62 bit application on 32 bit kernel? is that some sort of emulation? because i dont see any performance gain in such scenario?

[vijayninel]

Peculiar behavior......not making much sense to me.

[KiD0M4N]

Originally Posted by initpidzero 64 bit application on 32 bit kernel? is that some sort of emulation? because i dont see any performance gain in such scenario?

What seems to be the confusion The OS design is different from that of Windows.

The CPU can operate in 64 bit mode when running user mode applications in MAC OS X (unlike Windows.)

@Ad1: I cannot run VMWare Fusion if I run the 64 bit mode kernel as VMWare has not released 64 bit kexts yet.

Regards,
Karan Misra

[ManISinJpr]

^^ Thanks god-of-the-underworld, now it made more sense.

[ManISinJpr]

^^ LMAO.....ROTF there Kid0. you really are creatiive editor.......hats OFF !