Kexts, or kernel extensions are drivers that are installed to /System/Library/Extensions/.Kext files often have the “.kext” extension and allow for extra hardware support and and in the case of OSx86, to replace Appleʼs original drivers with ones that are optimized for use on PCs. Leopard holds kext files/folders in the /System/Library/Extensions folder, at boot time the relevant kext are uploaded from Extensions.mkext this is a cache folder that contains kext related to the installed hardware. If you loves your hackintosh then take a full backup of your kexts because some kexts may disappear after the update procedure.
For making backup of your Kexts open Terminal and type in these commands:
cp -r /System/Library/Extensions /System/Library/Extensions.backup
cp -r /mach_kernel /mach_kernel.backup
For restoring your Kexts open Terminal and type in these commands:
cp -r /System/Library/Extensions.backup /System/Library/Extensions
cp -r /mach_kernel.backup /mach_kernel