vansmith
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To quickly answer my title post, probably nothing. This doesn’t mean though that it can’t hurt to understand what it means for you. For the sake of brevity, I will not be discussing the differences between 32-bit and 64-bit simply because that is irrelevant to the purpose of this post. The purpose here is to explain the "usefulness" of 64-bit to the daily usage of your Mac. In case you’re interested, I quote Apple’s description of what increased 64-bit support means: "Today’s Mac computers can hold up to 32GB of physical memory, but the 32-bit applications that run on them can address only 4GB of RAM at a time. 64-bit computing shatters that barrier by enabling applications to address a theoretical 16 billion gigabytes of memory, or 16 exabytes. It can also enable computers to crunch twice the data per clock cycle, which can dramatically speed up numeric calculations and other tasks."
First off, this is not the first release of OS X to include 64-bit support. What is important to note is that the pervasiveness of 64-bit support is now at a point where it affects the core of the machine should you choose to utilize it. Secondly, just because there is increased 64-bit support doesn’t mean that you should or need to utilize it. Many of us will work with 32-bit software most of the time or, even if you do use 64-bit software (which encompasses most of the system software now), you probably won’t be using features that are unique to 64-bit. Nonetheless, here are some questions that I have seen popping up and my best attempts to answer them.
Q: Does my Mac support 64-bit?
A: I’m only going to answer this in regard to those who use Intel Macs simply because of the dropped support of PPC Macs in Snow Leopard. For those who use Intel Macs, the quickest way to determine if you are using a 64-bit Mac is to see what Intel processor you are using. Simply put, if you are using an Intel Core Duo, you are using a 32-bit processor. If you are using an Intel Core 2 Duo on the other hand, you are using a 64-bit processor. To check the type of processor you are using, simply go to > About This Mac > Processor. On my machine for example, I am using a "2.1 GHz Intel Core 2 Duo" and therefore, I have a 64-bit capable processor.
Q: If I don’t have a 64-bit capable processor, can I still use Snow Leopard?
A: Yes but you won’t get any of the arguable benefits that come with 64-bit computing. This does not render Snow Leopard useless as many of the great enhancements and improvements are independent of the increased 64-bit support such as Grand Central Dispatch and OpenCL. For descriptions of these technologies, go here. In fact, for the near future at least, those who boot into a 64-bit kernel will likely experience more problems than those who stick with the default 32-bit kernel.
Q: I have heard that I can boot into a 64-bit kernel. Should I?
A: While for some the idea of booting into a 64-bit kernel is nice, it isn’t advisable (for now). The reason this is the case is because of particular software that depends on 32-bit kernel extensions. I won’t go into great detail here as to what kernel extensions are but 32-bit kernel extensions depend on a 32-bit kernel and 64-bit kernel extensions depend on a 64-bit kernel. While this may seem irrelevant to the average user, using the proper kernel is imperative to the proper operation of particular pieces of software.
As an example, here is the status of the three major virtualization options and their 64-bit kernel support. As you can see here, Parallels is not supported on a “Snow Leopard 64bit Host”. The VMWare "Team Fusion" has also stated that, "While VMware Fusion 2.0.5 offers experimental support for the 32-bit version of Snow Leopard, VMware Fusion 2.0.5 is NOT compatible with the 64-bit version of Snow Leopard." I'm still unsure as to the status of VirtualBox under a 64-bit kernel (I have read conflicting things) but I will get back to you once I try. The important thing to get from this is that you shouuld check the status of software you use frequently before you boot into a 64-bit kernel. This should not be much of an issue though for most people as Snow Leopard defaults to a 32-bit kernel.
Q: I understand the problems that may come with booting into a 64-bit kernel but I still want to try it. How do I do this?
A: Should you wish to boot into a 64-bit kernel, you can hold down the 6 and 4 buttons during boot. It is strongly advised that you test all critical applications first before you start using them for important projects, work, etc. If in doubt, don't boot into a 64-bit kernel until you hear from the software maker that either the application is known to work with a 64-bit kernel or a software update is made available.
Q: How do I check if I am running a 64-bit kernel?
A: Instead of explaining it myself, I simply refer to the VMWare blog post mentioned earlier (see here) which has clear instructions on how to check whether or not you are running a 64-bit kernel.
If you have any questions that aren’t answered here, don’t hesitate to ask and we will do our best to answer them.
EDIT: Forgot links first time around.
First off, this is not the first release of OS X to include 64-bit support. What is important to note is that the pervasiveness of 64-bit support is now at a point where it affects the core of the machine should you choose to utilize it. Secondly, just because there is increased 64-bit support doesn’t mean that you should or need to utilize it. Many of us will work with 32-bit software most of the time or, even if you do use 64-bit software (which encompasses most of the system software now), you probably won’t be using features that are unique to 64-bit. Nonetheless, here are some questions that I have seen popping up and my best attempts to answer them.
Q: Does my Mac support 64-bit?
A: I’m only going to answer this in regard to those who use Intel Macs simply because of the dropped support of PPC Macs in Snow Leopard. For those who use Intel Macs, the quickest way to determine if you are using a 64-bit Mac is to see what Intel processor you are using. Simply put, if you are using an Intel Core Duo, you are using a 32-bit processor. If you are using an Intel Core 2 Duo on the other hand, you are using a 64-bit processor. To check the type of processor you are using, simply go to > About This Mac > Processor. On my machine for example, I am using a "2.1 GHz Intel Core 2 Duo" and therefore, I have a 64-bit capable processor.
Q: If I don’t have a 64-bit capable processor, can I still use Snow Leopard?
A: Yes but you won’t get any of the arguable benefits that come with 64-bit computing. This does not render Snow Leopard useless as many of the great enhancements and improvements are independent of the increased 64-bit support such as Grand Central Dispatch and OpenCL. For descriptions of these technologies, go here. In fact, for the near future at least, those who boot into a 64-bit kernel will likely experience more problems than those who stick with the default 32-bit kernel.
Q: I have heard that I can boot into a 64-bit kernel. Should I?
A: While for some the idea of booting into a 64-bit kernel is nice, it isn’t advisable (for now). The reason this is the case is because of particular software that depends on 32-bit kernel extensions. I won’t go into great detail here as to what kernel extensions are but 32-bit kernel extensions depend on a 32-bit kernel and 64-bit kernel extensions depend on a 64-bit kernel. While this may seem irrelevant to the average user, using the proper kernel is imperative to the proper operation of particular pieces of software.
As an example, here is the status of the three major virtualization options and their 64-bit kernel support. As you can see here, Parallels is not supported on a “Snow Leopard 64bit Host”. The VMWare "Team Fusion" has also stated that, "While VMware Fusion 2.0.5 offers experimental support for the 32-bit version of Snow Leopard, VMware Fusion 2.0.5 is NOT compatible with the 64-bit version of Snow Leopard." I'm still unsure as to the status of VirtualBox under a 64-bit kernel (I have read conflicting things) but I will get back to you once I try. The important thing to get from this is that you shouuld check the status of software you use frequently before you boot into a 64-bit kernel. This should not be much of an issue though for most people as Snow Leopard defaults to a 32-bit kernel.
Q: I understand the problems that may come with booting into a 64-bit kernel but I still want to try it. How do I do this?
A: Should you wish to boot into a 64-bit kernel, you can hold down the 6 and 4 buttons during boot. It is strongly advised that you test all critical applications first before you start using them for important projects, work, etc. If in doubt, don't boot into a 64-bit kernel until you hear from the software maker that either the application is known to work with a 64-bit kernel or a software update is made available.
Q: How do I check if I am running a 64-bit kernel?
A: Instead of explaining it myself, I simply refer to the VMWare blog post mentioned earlier (see here) which has clear instructions on how to check whether or not you are running a 64-bit kernel.
If you have any questions that aren’t answered here, don’t hesitate to ask and we will do our best to answer them.
EDIT: Forgot links first time around.