Is Lion true 64-bit OS?

Discussion in 'Mac OS X Lion (10.7)' started by ApplesAOranges, Jun 8, 2011.

  1. macrumors 6502

    Jan 7, 2011
    Or will it still run 32-bit software?
  2. Moderator emeritus


    Dec 10, 2008
    64-bit kernel can run 32-bit apps, so support for 32-bit is still there.
  3. thread starter macrumors 6502

    Jan 7, 2011

    Thanks for the answer though.
  4. macrumors 68000


    Dec 19, 2008
    London Ontario
    Bummer? I don't understand.:confused:
    It is a true 64bit OS. doesn't get any more 64 bit. Just because it is backwards compatible is not a bummer. It is a huge feature.
  5. macrumors 6502a

    Apr 1, 2007
    Honestly I think most of the people touting on about 64 bit being awesome in this forum have absolutely no idea what it means...
  6. macrumors 65816

    Feb 15, 2011
    Haha i've been guilty of that:) but know i know;)
  7. Riemann Zeta, Jun 8, 2011
    Last edited: Jun 8, 2011

    macrumors 6502a

    Feb 12, 2008
    It is as 64bit as x64 gets. As is Snow Leopard if you change the boot flag so that it uses the real x64 kernel. The whole point of the AMD64 architecture is that all programs compiled for the regular i386 (x32) Intel architecture run without modification--there is no performance loss or emulation "danger" when running x32 programs on an x64 chip. In fact, I think that all x86 processors--no matter how advanced or altered from the original 80186 architecture they are--still have to spend the first few microseconds after initial power-on in 80186 "Real Mode" (the legacy 16bit mode) before they can switch to the modern standard "Protected/Long Mode."
  8. macrumors P6


    Jan 24, 2010
    By your definition, even 64-bit Windows is a "true" 64-bit OS either.
  9. macrumors 65816


    Aug 6, 2008
    St. Louis
    I'm pretty sure OS X went "true" x64 with 10.6.
  10. macrumors 6502a


    Jul 15, 2010
    Only two of all my processes are not 64-bits. Dropbox and FlashPlayer safari plugin
  11. Atarikid, Jun 8, 2011
    Last edited by a moderator: Jun 8, 2011

    macrumors regular

    May 14, 2011
    Thats because you do not understand what 64bit really is.

    Anyway, did you know that most apps run slower within 64bit (even 64bit compiled apps)? Uses more memory? Have bigger memoryleaks when not properly coded?
    The only advantage that 64bit brings is, it can address more memory compared to 32bit. This can be a advantage but also a disadvantage.

    Very true!
    As a developer I wish 64bit never did see the light of day. 32bit is much easier to program without issues. Memoryleaks are a pain with 64bit. :-/

    It is a hype created by Intel. Period.
  12. macrumors newbie

    Jun 5, 2011
    Folsom, Ca
    I'm sorry but I have to disagree. A properly written 64 bit app and OS more efficiently use CPU cycles by reducing the number of loads into the various registers in the CPU core to handle large data sets. This means that the CPU can crunch more data every clock cycle. This may not make launching Firefox all that much faster, but crunching on a video transcode is. Or doing physics calculations for a video game. Or rendering an image out of its compressed format for displaying on the screen. (Before you mention MMX/SSE, I must remind you that one is still oft limited by the general purpose registers for a number of operations that MMX/SSE are not suited for)

    Any time you are dealing with large pieces of data where repetitive instructions are necessary (basically all of modern computing) you see the benefits of 64 bit. Not to mention PAE is significantly slower than a direct page/memory address for +4gb of memory that 64 bit CPU's and OS's offer.

    Like any new way of programming methods and techniques need to be augmented or changed, but in general it provides a not so insignificant performance boost.
  13. macrumors regular

    May 14, 2011
    Floating point calculations are about 20% slower in 64bit compared to 32bit.
    Most video and audio has floating point calculations. That is why for example Handbrake 64bit is about 10-15% slower then Handbrake 32bit (especially noticeable when converting to H264).
    Anyway, as you said, bigger amount of memory can be addressed but this not always makes up for the slower FP lag.
  14. macrumors 6502a


    Aug 14, 2006
    I'm just hoping the next iLife suite is 64bit, mainly for iMovie.
  15. macrumors 601

    Mr. Retrofire

    Mar 2, 2010
    You sound like Libertyforall1776 on macupdate dot com. But Apple can help you.
  16. macrumors P6


    Jan 24, 2010
    I am not a fan of Libertyforall...
  17. macrumors newbie

    Jun 5, 2011
    Folsom, Ca
    When doing floating point you should be using MMX/SSE. FP calculations done by the general execution units are inaccurate and slow as all hell.
  18. macrumors 68040


    Feb 5, 2009
    I don't know when it went "true" x64, but I do know that the only computers Apple recommends booting into x64 mode are 2011 Macbook Pros, 2011 iMacs and Mac Pros dating a year or a few back.

    Other/previous models will, but it's not supported per say.

    From what I understand, 10.7 will always boot into 64 bit mode, hence the 64 bit CPU requirement.
  19. macrumors 6502a


    Sep 25, 2006
    According to an Apple support article I read yesterday, all iMacs from 2008 are capable so read the facts before you spread FUD.
  20. slb
    macrumors 6502

    Apr 15, 2005
    New Mexico
    What the...? Why is 32-bit support a bummer?

    The MacRumors forum is one of the most misinformed Mac communities I've seen when it comes to technical issues. Half the people don't even know what 64-bit means or that OS X's system frameworks were 64-bit back in 2007. The only thing changing for most users in Lion is that the kernel will be 64-bit, which will make no discernible difference to them anyway, yet for some reason people obsessively fret over whether or not they can boot the 64-bit kernel.

    You don't need the 64-bit kernel to run 64-bit applications, so it's bizarre that anyone is even thinking about it. You should only care if you're a driver developer.

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