Snow Leopard and 64-Bit

Discussion in 'macOS' started by SAG3194, Aug 29, 2009.

  1. SAG3194 macrumors 6502

    SAG3194

    Joined:
    Jan 4, 2009
    #1
    Hi,

    I wanted to know how to enable 64-Bit on Snow Leopard. I noticed that it wasn't enabled by default.

    Thanks
     
  2. jmann macrumors 604

    jmann

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    #2
    It is for the apps, but not at kernel level. Hold the 6 and 4 key while booting up the computer. It is unnecessary though.
     
  3. gr8tfly macrumors 603

    gr8tfly

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    #3
    I assume you're talking about the kernel. Normally, you don't need the kernel to be in 64-bit mode (see other threads for more info on this).

    Snow Leopard runs 64-bit apps whether or not the kernel is in 64-bit mode.
     
  4. akutad macrumors regular

    akutad

    Joined:
    Jul 12, 2008
    Location:
    London, Ontario, Canada
    #4
    What is unnecessary. Perhaps a newbie question... What does the kernel do an what benefits are there if the kernel is 64 bit. Sorry about my ignorant technical knowledge.
     
  5. jmann macrumors 604

    jmann

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    #5
    I don't know specifically. I just read it somewhere that it wasn't really needed. ;)
     
  6. goMac macrumors 603

    Joined:
    Apr 15, 2004
    #6
    The 64 bit kernel lets you use more the 32 gigs of RAM if you have that much installed in your computer.

    I.E.: You don't need to be using it.
     
  7. gr8tfly macrumors 603

    gr8tfly

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    #7
    The main advantage of running the kernel in 64-bit mode is addressing large amounts of RAM (going past 4GB). The other advantages of 64-bit aren't really utilized in the kernel (more efficient code, to put it simply). 64-bit applications can take fully utilize 64-bit mode - independent of kernel mode.

    So, unless you have a specific need for the kernel to use that much RAM (or its kexts), there's no real gain by running it in 64-bit mode. In fact, since the kexts also need to be 64-bit, you will most likely run into compatibility issues with apps that don't have 64-bit kexts (Parallels Desktop, for example).
     
  8. goMac macrumors 603

    Joined:
    Apr 15, 2004
    #8
    To clarify:

    64 bit mode doesn't impact your computer addressing 4 gigs or more, only the kernel addressing 4 gigs or more.

    And if you don't know how much RAM your kernel is using, you probably don't need kernel 64.
     
  9. david803sc macrumors member

    david803sc

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    Jul 11, 2008
    Location:
    Lake Wylie, SC
    #9
    I have a iMac 3.06 GHZ 4 GB RAM, I run the kernel in 64bit mode, to me it feels a little bit more snappier in 64 than 32, though the difference is not great but I do not have any hardware compatibility issues in 64 bit mode, my printer drivers are working fine, everything except my VMWARE FUSION runs in 64 I do not use vmware very often so, when I need to use it I just reboot holding the 3 and 2 keys.

    Since I want to run in 64 bit mode even if there is little difference I modified the boot file as shown on the Apple Support Website to always boot in 64 unless holding the 3 and 2 keys down.

    For me this works best, each person has to find what works best for them as new hardware is released and more developers write software and drivers for 64 bit kernel Extensions this will eventually become the norm

    David
     
  10. david803sc macrumors member

    david803sc

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    #10
    gomac you posted while I was working on my post the other poster was correct though that a lot of the built on applications have code optimized for the 64 bit Kernel Extensions, they may run a little faster due to the code being optimized that way, although the difference is probably pretty minimal, what we need is benchmarks on two new mac one with 32 bit extensions and one with 64 bit extensions both with 4GB's of ram and do side by side comparisons.

    David
     
  11. goMac macrumors 603

    Joined:
    Apr 15, 2004
    #11
    As a software developer, I can tell you, you can't optimize applications for a 64 bit kernel. You can write 64 bit applications, that's it. There is no wave of upgrades coming for applications to take advantage of the 64 bit kernel.

    Your applications will be just as optimized whether you run them on the 32 bit or 64 bit kernel. Applications will still run in 64 bit mode on the 32 bit kernel.
     

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