Is it safe to try out the 64-bit kernel?

Discussion in 'macOS' started by hajime, Jun 4, 2010.

  1. hajime macrumors 601

    Jul 23, 2007
    Hello. I am using a MacBook Pro 2010 (i7, OS 10.6.3). I sometime use Fusion 3.1 to access to Windows Vista 64-bit partition under BootCamp. I read that Snow Leopard is defaulted to 32-bit. 64-bit can be enabled by pressing 6 and 4 during startup. Is it safe to try out the 64-bit kernel? I worry that if there is a compatibility issue such as problems with drivers or softwares, my system may get messed up even when the system returns to 32-bit kernel next time it boots. Also, is it safe to use Time Machine to back up the system during the trial period? So far, TM has been backing up my laptop running 32-bit. I wonder if switching the 32-64 bit kernel back and forth will mess up the TM backups. Thanks.
  2. larkost macrumors 6502a

    Oct 13, 2007
    The first thing to emphasize is that this only affects whether your kernel is running in 32bit mode or 64bit mode. User-space applications run in 64bit mode (assuming you have a 64bit processor and they were compiled for 64bit) by default even on a 32bit kenel. Note that this is not the case on Windows, where they have made things much more complicated (two versions of the registry running at the same time, etc).

    So the only things that are really impacted by this are drivers (as you mentioned), and things that use a lot of memory (and I really mean a lot... like more than 4 Gigs). There are some other things that the 64 bit kernel can do better, but most of them only come into play when you are running a server (with the timing tweaks that 'server brings to play).

    All this being said, unless you have a VPN installed (usually involves a kernel extension), then you are probably good to try holding down 6-and-4. You are probably not going to notice any difference unless you are in a very special case. And the chances of messing up anything where a reboot is not going to solve them are almost 0.
  3. lewis82 macrumors 68000


    Aug 26, 2009
    Totalitarian Republic of Northlandia
    I use it daily since september, and have no problems.

    You can use it :)
  4. scaredpoet macrumors 604


    Apr 6, 2007

    Just to clarify on this point: OpenVPN isn't affected, since it is a userspace implementation and doesn't require a kernel extension. Other types (PPTP, IPSec, Cisco) ARE affected though.

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