64-bit Mode Snow Leopard

Discussion in 'macOS' started by holden57, Aug 28, 2009.

  1. holden57 macrumors member

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    Jul 18, 2009
    #1
    I did a bit of reading on the internet, and it looks like most computers will not boot into 32-bit mode by default with 10.6. It appears that if while booting the user holds the 6 and 4 keys, the computer will boot into 64-bit mode.

    Does anyone know anything about this? Will the computer always boot into 64-bit mode if this is done once? Will it even make a difference? Will the average user want to do this?
     
  2. Krafty macrumors 601

    Krafty

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    #2
    No.

    And yes. Why they want to do this is beyond me, tbqh.
     
  3. Wraz macrumors regular

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    Jun 1, 2009
    #3
    i just did this. i thought it were suposed to say something but never did?
    i can't honestly feel any difference at all
     
  4. holden57 thread starter macrumors member

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    Jul 18, 2009
    #4
    Okay, that's what I saw from researching a bit on Google. I'm probably going to purchase Snow Leopard tonight, so I was merely curious. Also I read something about launching applications in 64-bit mode, is that something someone could do from 32-bit mode boot, and would they want to? Or is it just the same as before.
     
  5. Hellhammer Moderator

    Hellhammer

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    #5
    All apps that comes with your Mac (aka Apple apps) are 64-bit, no matter are you using 32-bit kernel or 64-bit. There's a thread about why not to use 64-bit kernel. It made it unstable and sluggish, plus only thing you get is that you can say you have 64-bit kernel
     
  6. holden57 thread starter macrumors member

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    #6
    Okay, thank you! :)
     
  7. Frosties macrumors 6502a

    Frosties

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    #7
    Just pointing out that other posts have had speed increase. So it not a final call if 32bit kernel is better or not.
     
  8. Hellhammer Moderator

    Hellhammer

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    #8
    I haven't heard about that. It's still not recommended because some drivers are 32-bit only and Apple would've make it a default kernel if they wanted so.
     
  9. Frosties macrumors 6502a

    Frosties

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    #9
    The issue with old drivers gives that it's often more compatible with 32bit kernel now but as many manufacturers on the pc side will start shipping windows 7 64bit as default instead of Vista 32bit I think we will have a shift to 64bit on both sides soon.
     
  10. krayziekray macrumors 6502

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    #10
    Assuming that 64bit works on your machine (holding the 6 and the 4 together works), can you set the default boot into the 64bit kernal?

    After some internet seraching i found a command that seems to work on mac servers, but will it work on Snow Leopard? Still waiting for my copy, so can't test it myself.

    Code:
    sudo systemsetup -setkernelbootarchitecture x86_64
    Also, are there any advantages/disadvantages of doing so? I know the 32bit apps will continue to run at 32bits, but other than that anything else? Battery life maybe? Shouldn't think so as 64bit in theory would save battery, right (fewer clock cycles)???

    :apple: KrayzieKray :apple:
     
  11. Hellhammer Moderator

    Hellhammer

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    #11
    http://www.macupdate.com/info.php/id/32252/32--or-64-bit-kernel-startup-mode-selector
     
  12. krayziekray macrumors 6502

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    #12
  13. Wraz macrumors regular

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    #13
  14. krayziekray macrumors 6502

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    #14
    Well after some more internet searching, I have read the following and not sure if its correct.

    So it doesn't matter if you boot into 32 or 64 bit kernel, apps will run in 64bit????

    Anyone care to comment?

    :apple: KrayzieKray :apple:
     
  15. bcaslis macrumors 68020

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    #15
    I've been testing SL for months (I was part of Apple's beta seeding program). This is correct, SL isn't windows. Apps will run as 64 bit as long as they are compiled for it. There is both a 32 bit and 64 bit kernel (unlike Windows which has separate installs depending on 32 or 64 bit).

    The reason for defaulting to 32 bit that everyone panicking over are missing are:

    1.) There's no current need for the kernel to need 64 bit support. Currently driver requirements don't need more than 4GB of memory. In the future with uber video cards with 128GB of video ram this may be needed. But it's not right now.
    2.) There will always be memory for the kernel. It's the very first thing that loads so needing space in the first 4GB isn't a problem.
    3.) This is the big one. Any kernel extension for the 64 bit kernel needs to be 64 bit. So things like Fusion and Parallels won't work at all until they produce 64 bit versions. They don't have them right now. A 64 bit kernel introduces compatibility problems. This was one of the big issues with Vista.

    Apple's approach really is brilliant if you look at OS history. They can run with kernel compatibility now, get full 64 bit app support, and later once more drivers are available can switch the kernel to 64 bit with a minor update. Developers can develop and test now for the 64 bit kernel without users suffering. It's an elegant approach that people complaining on forums like this are completing missing.
     
  16. krayziekray macrumors 6502

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    #16
    Thanks for clearing that up :D

    :apple: KrayzieKray :apple:
     
  17. NATO macrumors 68000

    NATO

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    #17
    According to Apple:

    "The 32-bit kernel fully supports 64-bit applications, all system libraries that 64-bit applications use are fully 64-bit, and 64-bit applications have a full 64-bit virtual address space of 16 exabytes available to them on Mac OS X. The primary benefit of a 64-bit kernel is to improve the efficiency of accessing over 32GB of RAM." - link

    I don't have anywhere near 32GB RAM so I'm happy enough since it doesn't really affect performance as everything else is 64-bit.
     
  18. genshi macrumors 6502a

    genshi

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    #18
    Just an FYI; I just finished installing Snow Leopard an hour ago on my late 2008 unibody MBP and when it restarted (I boot in verbose mode) the first couple of lines said something to the affect of "Pre Enabled default 64 Bit, Kernel version Darwin 10.0.0.0." so, at least in my case, it seems to have booted the 64 bit kernel by default (?) and so far, everything in terms of the Apple programs (Mail, Safari, etc.) is blazingly fast.

    No issues thus far, except Cyberduck wouldn't launch, but I downloaded their latest beta which seems to work fine in Snow Leopard.
     
  19. krayziekray macrumors 6502

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    #19
    Could you just not install Rosetta that comes with the Snow Leopard install disc. I tried running Photoshop, and it asked if i wanted to install Rosetta .... is this not advisable?

    :apple: KrayzieKray :apple:
     
  20. nick9191 macrumors 68040

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    Feb 17, 2008
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    Britain
    #20
    I've heard that the constant 32/64 bit translation between apps and the system is the reason some felt Leopard was slower than Tiger.

    Perhaps someone more knowledgeable than me could comment.
     

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