Testing shows that doing so is highly beneficial, even on Mac OS X Leopard.Ĭhecking whether 64-bit kernel is in use The configuration file approach for always booting into 64-bit PERMALINK Uncheck the “Open in 32 Bit Mode” option. The main problem being that there are only a handful of 64-bit applications available as of September 2009. This was/is possible even with Mac OS X 10.5 Leopard. You can still run 64-bit apps on a 32-bit kernel! PERMALINKĮven if you cannot or do not boot the Mac OS X Snow Leopard kernel into 64-bit mode, you can run your 64-bit apps as 64-bit, and they can take advantage of all the memory in the machine. Some machines do have a 64-bit EFI but are not able to boot into K64 (the iMac7,1 falls into that category).

If it reads EFI32, then your Mac cannot be booted into a 64-bit kernel.Ī 64-bit EFI is required to boot into K64 but is not always sufficient.

To determine if your Mac has 32-bit or 64-bit firmware, copy/paste the following command shown in red into Terminal (Terminal is found in the /Applications/Utilities folder): llcMP:~ lloyd$ ioreg -l -p IODeviceTree | grep firmware-abiĪs shown above, the firmware-abi has the value EFI64, indicating that my Mac Pro is 64-bit capable. With 32-bit firmware, you cannot boot into 64-bit kernel it’s not possible. See this Apple tech note for which machines can boot the 64-bit kernel You Mac might be a few years old and have 32-bit EFI firmware (the code that runs to boot the Mac). Does your Mac have 64-bit EFI firmware? PERMALINK You’ll want to verify if your software has any issues in 64-bit mode. Apple really can’t be faulted here, but you can make an intelligent choice for yourself. The reason not to boot into 64-bit mode is compatibility with software drivers of various kinds. But they won’t see full performance that way. Your 64-bit programs (if any) will run fine on a 32-bit kernel, gaining the benefits of 64-bit-ness. Why not get a good chunk of that for about $25? Tests of photographic applications show that the gains of booting with the 64-bit kernel can be substantial, keeping in mind that a 30% gain via hardware often costs several thousand dollars more. Update! The 2010 Mac Pro now boots the 64-bit kernel by default. Since page was written, over a year has passed. performance is still improved over Leopard.(I think Microsoft should change the name, it’s a perfect fit!). Known as Windows) turned off a lot of users. Like bad breath, bad press makes a lasting first impression. it keeps compatibility high with drivers and specialized software, which lowers hassles for users.But Apple defaulted to a 32-bit kernel for good reasons. Update: the install disk for the 2010 Mac Pro now defaults Mac OS X 10.6.4 to 64-bit mode.īy default in 2009, Snow Leopard boots into a 32-bit kernel, an odd proposition for an OS claiming to be 64-bit. Updated - Send Feedback Related: Apple macOS, Mac Pro, sudo

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