
Even though Apple has been hyping up the 64bit nature of its ucpoming Snow Leopard operating system, stating it will be the first Mac OS X release to be 64bit top-to-bottom, reality turns out to be a little bit different so far. With the current Snow Leopard seed, only Xserve users get the 64bit kernel and drivers - all other Macs default to 32bit. By holding down the '6' and '4' keys during boot, you can to boot into full 64bit mode - that is, if your Mac supports it. As it turns out, some Macs with 64bit processors cannot use the 64bit kernel because the EFI is 32bit.
Note: I should have included in the article that 64bit applications will run just fine (including benefits) on a 32bit kernel in Mac OS X. Since this was already possible in Leopard, I assumed people were well aware of that. Turns out some were not, so my apologies for that.
Member since:
2006-07-14
The obvious question, is what impact does that mode of operating have on operating system performance? Does it limit the number of threads the kernel can handle? Or the memory it can address? How does a 32 bit OSX kernel manage more than 4 gb of memory, or is the memory management 64 bit? What parts of the kernel stay in 32bit mode? Anything other than device drivers?
If there is no difference, then why the different behavior with the Macs' listed in the chart? Is there a good technical reason for booting in 32 bit mode over 64 bit?