As of XNU 1228.15.4 (9.8.0), there is a modification in the kernel that prevents the computer from going to sleep without a registered power-management extension. However, the extension used on Apple computers to handle this (AppleIntelCPUPowerManagement.kext) can not be used on generic computers running a Darwin-based OS. This extension aims to provide a placeholder implementation to re-enable sleep with the latest version of the XNU kernel.

Currently updated to support up to Darwin 11.3.0 / Mac OS X 10.7.3 As well as Darwin 10.8.0 / Mac OS X 10.6.8