I successfully installed a 32-bit copy of 16.04 on my old 2006 MacBook Core Duo from a USB stick with help from rEFInd. Now I've mucked around a bit and want to reinstall a fresh copy of Ubuntu. The problem is when I formatted my hard drive during the first Ubuntu install, it looks like I destroyed the boot manager, and definitely the rEFInd functionality. It does not boot into a USB drive now, either with the original USB stick I used or with a newly formatted USB stick made with the Ubuntu Startup Disk Creator.

Normal boot procedure now flashes a folder icon with a question mark for a half of a second before booting to the current Ubuntu. When the USB stick is inserted, holding down the Option key shows only one partition called "Windows", which is the Ubuntu volume. Any thoughts about how to regain the ability to boot from a USB device?

  • Please run the Boot Repair utility and select the "Create BootInfo Summary" option. (DO NOT click "Recommended Repair," at least not yet!) When asked whether to upload the report, click "Yes," and then post the URL provided here. This will give us more details about your configuration, which is required to base an answer on more than guesswork. – Rod Smith May 29 '17 at 1:10
  • So the pastebin url was blank. I just copied and pasted the txt output into my own pastebin link. Here – Michael Jun 1 '17 at 2:00

You've got a GPT disk with a hybrid MBR, an Ubuntu installation, and nothing else that I can see. This is a very weird setup. You're better off with one of two other configurations:

  • Pure BIOS/CSM/legacy -- Treating the computer like an old BIOS-based computer works well. Wipe the partition table and create a regular MBR configuration with no GPT data, then install with a BIOS-mode version of GRUB. If you want to preserve your data, you can use gdisk to convert from GPT to MBR.
  • Pure EFI-mode -- You can wipe the hybrid MBR and install in EFI mode. If the computer has a 32-bit EFI, you'd need to install a 32-bit Ubuntu, but the usual Ubuntu installation media don't support EFI-mode booting, so you'll need to jump through some hoops to do so. This page of mine describes one way to do this.
  • Thanks Rod. Because this computer is 11 years old, I'm not too worried about having to install MacOS on this ever again - using this as an opportunity to experiment. I think I'll try the first option and do a BIOS/Grub install. Do you have more resources on how to do this? How big should the MBR partition be? When I wipe the partition table, is this done in the current Ubuntu terminal with gdisk? Was there anything special about the original Mac boot partition that I need to properly utilize all the hardware on the Macbook? Thanks again. – Michael Jun 3 '17 at 21:43
  • The MBR is not a partition; it's a partition table -- that is, a data structure that defines all the partitions on a disk. You'd convert the disk to MBR form using GParted, parted, fdisk, gdisk (only if you want to preserve the existing partitions in MBR form), or some other tool. – Rod Smith Jun 4 '17 at 0:52
  • I see thank you. How do I erase the GPT partition map and make a MBR in gparted while the disk is mounted? Sorry if these questions are very basic. – Michael Jun 4 '17 at 1:29
  • You should not attempt to do that while the disk is in use. If you're installing a new OS, do it from that OS's installation medium. – Rod Smith Jun 4 '17 at 2:04
  • Great that's what I thought. But this is part of my problem: I can't see the live USB image either when I "option" into the remnant of the MacOS booting procedure, or when I "Shift" into the GRUB. I can't initialize the new OS install. Doesn't see it. – Michael Jun 4 '17 at 13:42

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