Upgrading a netbook EFI install of Mac OS to 10.5.7

I wrote this answer in response to an email, and thought it would probably be better to share it with everyone 😉

• Download the 10.5.7 Combo update from Apple (you can use the Delta update as downloaded from Software Update if you want – but I don’t use these even on real Macs: If you run Disk Utility’s ‘Repair Permissions‘ after a Delta Update, you’ll get lots of unfixable differences, but if you use the Combo Update there will be none of these);
• Download the 10.5.7 Updated Driver pack from this site;
• You will need to use either the ‘sudo‘ (assume the privileges of the root user with your password) or ‘su‘ (become the root user with the root user’s password) commands with a Terminal.app session, so ensure that you have a Mac OS user account with a password set (in the former case) or know the root password (in the latter);
• Do NOT reboot your computer until both of the following steps are complete:
  • Mount your EFI partition (if you’re not sure how to do this, then see here and read on below) and rename your current Extensions folder from /Volumes/EFI/Extensions (without Chameleon) or /Volumes/EFI/Extras/Extensions (with Chameleon) to be named “Extensions-10.5.6” (or similar). Do this by running the commands:
    

    	cd /Volumes/EFI/Extras
    	  - or -
    	cd /Volumes/EFI/
    
    	sudo mv Extensions Extensions-10.5.6
    	  - or -
    	su root -c mv Extensions Extensions-10.5.6
    

    Within this folder (/Volumes/EFI/ or /Volumes/EFI/Extras/ if it exists) extract the 10.5.7 update: the command to do this, assuming that you’ve downloaded the 10.5.7 updated drivers into your Downloads folder, is either:

    	sudo tar -xjvpPf ~/Downloads/Extensions-10.5.7.tar.bz2
    	  - or -
    	su root -c tar -xjvpPf ~/Downloads/Extensions-10.5.7.tar.bz2
    

    Finally, run /Volumes/EFI/update.sh in order to regenerate the Extensions.mkext to reflect the new drivers. This will simply be:

    	sudo /Volumes/EFI/update.sh
    	  - or -
    	su root -c /Volumes/EFI/update.sh
    

    … and then your drivers are fully updated! But don’t reboot until you’ve also completed the following step…

  • Now you can install the Apple Combo update, allow it to run, and reboot when prompted. The machine will restart, boot as far as the Apple logo, sit with a spinner for a while, and then reboot again: this is completely normal, and happens on real Macs too.
• You should now have a fully working 10.5.7 installation! The only regression that I’ve noticed is that OS X now thinks that the Atom’s processor speed is 4.1GHz! 😉

A quick note from above: The first comment which I posted on the original Installation article contains a script to mount your EFI partition easily. The easiest way to use this is to copy the text from the page, and then perform the following actions in a Terminal.app session:

	mkdir -p ~/bin
	cat >> ~/bin/mountefi.sh

… at this point press Apple+V to paste in the copied text, and then press Ctrl+D to signal that you’ve finished. Now make the script executable by typing:

	chmod 775 ~/bin/mountefi.sh

You can now mount the EFI partition at will by running “~/bin/mountefi.sh” from a Terminal.app session. Please remember to unmount it afterwards with ‘cd ; sudo umount /Volumes/EFI‘ or ‘cd ; su root -c umount /Volumes/EFI‘ once you’re finished.