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I have successfully installed Ubuntu pangolin 64 bit on a mac mini 2011 5,3 ( server version ). I have used the Ubuntu iso which I then converted to .dmg and dd'ed into an usb stick. I didn't want to keep OS X installed so I deleted the current partition and reformatted the drive as ext4 for / + a small swap partition.

Everything seems to work nicely, but I have now a question since I read lots of reviews/howto when you people installed rEfit on Mac OS X. Did you use rEfit to be able to have a dual boot or there are other advantages by doing that ( apart that you will be able to download updated firmware for your hardware in the future via Mac OS ) like BIOS emulation and the like ?

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Is everything that you used legal? Are you actually aloud to install Ubuntu on a Mac? If not, do know that the Askubuntu community doesn't welcome questions relative to illegal use of software/hardware. –  Farid Nov 23 '12 at 16:54
    
There's no law against installing Ubuntu on a Mac. AFAIK, that's 100% legal in every country. (Installing OS X on a non-Apple PC, OTOH, is legally dubious in some countries.) –  Rod Smith Nov 23 '12 at 18:59

2 Answers 2

By doing some research I found that I am definitely using legacy boot ( MBR ) on my Ubuntu Linux

root@nas1:~# dmesg | grep 'EFI: mem' >/dev/null && echo "Installed in EFI mode" || echo "Installed in Legacy mode" Installed in Legacy mode root@nas1:~# [ -d /sys/firmware/efi ] && echo "EFI boot on HDD" || echo "Legacy boot on HDD"
Legacy boot on HDD

I think I will give GPT a go. So not only I have to convert to GPT table but I also have to convert/reinstall Ubuntu in EFI mode. That's ok, no problem.

what I might need to ask you still is how to find out whether my mac would support efi boot, because as far as I know it uses an hybrid efi ( not bios & not efi )

Thanks

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Intel-based Macs all use EFI 1.x implementations. They also all provide a BIOS compatibility layer (as do most UEFI-based PCs) so that they can boot BIOS-based OSes. This doesn't detract from their status as EFI-based computers. "Hybrid EFI" is a name that Gigabyte uses for some of its firmware; it doesn't apply to any Apple product, despite the fact that Macs use a hybrid MBR on the disk to trigger their BIOS compatibility layers. –  Rod Smith Nov 27 '12 at 5:11

rEFIt's primary purpose is as a boot manager -- it enables you to select which OS to run. As such, it has little or no utility on a Mac that runs nothing but Linux.

That said, your configuration is likely to have some sub-optimal aspects:

  • Chances are you've got a hybrid MBR setup. This is unnecessary in a Linux-only configuration, and since hybrid MBRs are flaky and trouble-prone, it's probably best to convert it to a straight-GPT or straight-MBR configuration. (Which works best depends on how you're booting -- use a straight-GPT setup for EFI booting and straight-MBR for BIOS booting.) You can use gdisk to either convert the hybrid MBR to a plain GPT setup or convert to a true MBR configuration.
  • Completely removing OS X means you won't be able to update your firmware, and adjusting boot loader options can be tricky. OTOH, note that if you keep OS X, you may need to keep that ugly hybrid MBR, depending on your model's capabilities.

If you convert to a plain MBR setup, rEFIt is likely to stop working. (I've never done this on a Mac, though, so I'm not 100% sure how it reacts. I have heard of people running with such configurations, though.) In such a setup, you can treat the Mac as being pretty much like a normal BIOS-based computer.

Converting to a straight-GPT setup means that the Apple's BIOS compatibility layer won't load, so you'll need to boot Linux in EFI mode. Chances are you don't now have an EFI boot loader for Linux installed, so you'll need to do some reconfiguration if you go this route. I've written a Web page on this topic, so consult it if you're interested. If you go this route, you'll probably want to replace rEFIt with rEFInd and a 3.3.0 or later kernel with EFI stub loader support, GRUB, or some other Linux EFI boot loader.


Edit/addition:

To see whether you've got a GPT, MBR, or hybrid MBR disk, install gdisk and then use it to view your partition table, as in:

$ sudo gdisk -l /dev/sda
Password: 
GPT fdisk (gdisk) version 0.8.5

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Of interest here are the MBR and GPT lines in the Partition table scan area. If you see MBR: protective and GPT: present (as in this example), it's a plain GPT disk. If it reads MBR: hybrid and GPT: present, you've got a hybrid MBR. If it reads MBR: MBR only and GPT: not present, then it's a conventional MBR disk.

Alternatively, you can view the disk with Linux's fdisk. If you see nothing but a single type-0xEE partition, it's a plain GPT disk. If you see such a partition and other partitions, it's a hybrid MBR disk. If you see one or more partitions but none of them are of type 0xEE, then it's a plain MBR disk.

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Thanks for your reply Rod, is there any step which I can perform to diagnose whether I have a hybrid MBR setup ? –  Thomas Nov 24 '12 at 13:45
    
See my additional information, above. –  Rod Smith Nov 25 '12 at 0:46

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