Comment on: 64-bit Snow Leopard defaults to 32-bit kernel

[TheForestFloor]

I think there's a technical disconnect here.

If you boot into a 64bit kernel, none of your 32bit device drivers will work, so people who are upgrading will struggle. Drivers built for snow leopard will have both 32 & 64 bit code, but until that happens, booting into 64bit by default isn't the right way to go.

That said, 'booting into 64bit' only refers to the kernel. All of the other libraries that apps depend on, AppKit, FoundationKit, libc, etc are all 64 bit, and will load if a 64 bit processor is accessible. Also, any program that was compiled with 64bit code will run in 64bits period, giving you that (2x) improvement.

The biggest problem for users will be that their software (Photoshop, Logic, etc) will be 64 bit, but their plugins might not be. If any program has plugins or extensions that are not 64 bit, it will have to be relaunched into 32bit mode to use them. Contrary to contentcreator's comments, OSX does not 'grind a bit' when loading 64 bit code, nor does it load BOTH 32 and 64 bit. It loads 64bit code if it's dependent libraries and the processor support it. If not, it degrades gracefully (and speedily) to 32bit code.

That said, nearly all programs 32/64/ppc continue to run well on SL, and all of them get to take advantage of GCD when they run, so they run a bit faster as well.

In the pre-release versions of SL, all of the Macbook Pros, Mac Pros and XServes could be set to boot in 64bit by default (without 32bit device drivers), and the others (with the exception of the MBA and Mini) could be booted with the '64' keys held down. I guess they removed it to keep users from getting confused if their devices stopped working. My guess it will be the default for all machines once the driver community has moved all of their code over.

[ballmerisanape]

You should have written this article. Thanks for that very clear explanation... i'd like to believe that this is just another "hit piece" article.. but im guessing.. in this case.. the author just didn' t know what the heck they were talking about.

[myles taylor]

Thank you for that. People are going to flip about this and they don't even understand what it means.

[darkxeno]

Dear God some one here Knows what they are talking about. Once I heard about this I started digging around. To me this make total sense that they did this. I don't care if your PC or Mac 80% of the users of the system don't understand what goes on under the pretty pictures they see on the screen. So in order to save some headaches they did it this way. Im sure within two or three updates they will change over to total 64bit once software makers have gotten onto the wagon more then they are now.

[krushyou]

Wait a minute...If Apple discontinued PPC support how is a ppc program going to run? I am confused...

[krushyou]

Crap, nevermind someone else answered it below...

[Vegaman_Dan]

A thoughtful response that is logical, well put together, and doesn't have any agenda pro or con.

Please post more often.

[martin1212]

"Also, any program that was compiled with 64bit code will run in 64bits period, giving you that (2x) improvement."

Er, 64 bit does not give 2x improvement. I can't believe people are still saying that. Makes it hard for me to take anything else you wrote seriously...

[Endbringer]

Nice post, except for the 64-bit being twice as fast as 32-bit.