Any recent version of Ubuntu should not harm (or in any way modify) your Mac's EFI firmware. To give more details or absolute assurance about claims to the contrary, it would of course be necessary to detail and cite the claims (with a link if possible).

However, what you're probably thinking of is this. Fortunately, that only affected Ubuntu 11.04 (which is not even supported anymore), and has been fixed (and the fix shipped with every subsequent version's installation images, starting with 11.10). Therefore, there is almost certainly no need to be concerned anymore (unless you're trying to install from old 11.04 images for some reason).

There is one significant Mac EFI related issue with Ubuntu, but it is not dangerous and doesn't pose a threat to your computer. Often a Mac is unable to boot a CD/DVD or live USB created from the regular Ubuntu ISO image because Macs are incompatible with boot media that are set up to work with both BIOS and UEFI (multi-catalog media).

If that's the problem you're having, the solution is to use the special Ubuntu disk image made for Macs. Macs can boot Mac EFI or regular BIOS, so this image removes UEFI support, and can be booted on Macs.

That critical, dangerous, and fortunately fixed bug used to be one of the reasons to make sure to use the special Mac image. Now that it's fixed, the special Mac image is still more likely to work than the regular one, but the regular image is not dangerous.

See this excellent answer for a detailed explanation and technical information about the difference between the regular and Mac ISO images.

This applies only to 64-bit ISO images, so if you're using the 32-bit image, then your problem is different.

Assuming you're trying to install the 64-bit version of Ubuntu on your Mac, the special Mac ISO image for Ubuntu 12.04 LTS can be downloaded here.

• Specifically, here's a direct link to the ISO file.


• And if you want to download via bittorrent, here's a link to the .torrent file.

That page also contains links to download the text-based alternate CD image, if you want that. (It shouldn't be necessary though, unless you have highly specialized requirements.)

More generally, for people looking for other versions: The special 64-bit Mac ISO images are currently kept on the cdimage.ubuntu.com download server, categorized by version. (In particular, images for 13.04, the latest stable release as of the time of this writing, are here.)