Road to Mac OS X Snow Leopard: 64-bit to the Kernel

Build notes leaked on the web of a prerelease version of Mac OS X 10.6 Snow Leopard indicate that the software only supports enabling its new 64-bit kernel on certain machines, including the Xserve, Mac Pro, and MacBook Pro, but this does not mean Snow Leopard's kernel will be limited to 32-bit operation on consumer machines.

A 64-bit kernel requires all of its extensions to also be 64-bit. Kernel extensions or KEXTs include drivers for audio hardware, graphics adapters, networking, certain printing components, and other devices on the logic board or attached as peripherals. Until Apple delivers 64-bit versions of the nearly 300 extensions it ships with Mac OS X (not all of which will need to be supported on 64-bit Macs; many are legacy), it is limiting official 64-bit kernel support to a subset of Macs in prerelease builds of the new operating system.

Snow Leopard will deliver the first 64-bit kernel for Mac OS X. Earlier versions of the operating system, including today's Leopard, can run 64-bit software but do so using a 32-bit kernel. More accurately, whether running on 32 and 64-bit CPUs, Mac OS X loads the same kernel image and run it as a 32-bit process, although when run on 64-bit hardware, the 32-bit kernel switches into "long mode compatibility mode."

read more | digg story

Road to Mac OS X Snow Leopard 64-Bit: Santa Rosa PC Swindle

Snow Leopard's across-the-board leap to 64-bits, from the kernel to all of its bundled apps, will do more than just make more memory available. It also exposes a great PC swindle and highlights Apple's lead in 64-bit computing. Here's why. "Microsoft even changed the way the OS reports the amount of RAM available; rumor is, due to pressure from OEMs," the developer told us. "In Vista and prior, it reported usable RAM, while in SP1 they changed it to report installed RAM ignoring the fact that much of the RAM was unusable due to overlap with video memory." And so many PC users are installing 4GB of RAM in their PCs and thinking that it is being used by the system, when in fact it is no more beneficial than if the RAM were simply poked halfway into the CD slot.

read more | digg story