When I hold the C key on startup on OSX Yosemite 10.10.5 (macbook pro retina 2015 with force touch), it doesn't boot to the USB. Holding alt/option doesn't show the USB drive, and changing boot order in system preferences doesn't work either, as the USB doesn't show up. Upon plugging the USB into my macbook while it's on and running OSX, I get the error message "The disk you inserted was not readable by this computer.", which should indicate that linux is indeed installed correctly onto the USB.

I'm able to boot to this USB using a windows (10) system.

Used the commands in this video to install to the USB: https://www.youtube.com/watch?v=sDq1oaYRgeg

Using Grub bootloader. Installed "archlinux-2015.11.01-dual.iso". Booted i686. Formatted both partitions of the USB to ext4.

My question here is, what's a possible reason for me not being able to boot to the drive, and how would I fix it?


Best guess, based on the instructions to create the USB media, is that it's formatted MBR/ExtFS or FAT32. Mac will only boot from GUID/HFS+ without using something like rEFInd to manage the loading process.

  • Thanks! I formatted the USB to ext4. Can I change the formatting to GUID/HFS+ and reinstall Arch on that and have it work on most machines, or must I use rEFInd? – underscore Nov 25 '15 at 9:33
  • A bit above my pay grade, I'm afraid - maybe wait & see if you get a smarter answer from someone else. Nothing else will boot it if it's HFS, but idk whether rEFInd would allow you to work from ext4 – Tetsujin Nov 25 '15 at 9:40
  • 1
    You were right for the most part. The fact that I wasn't following instructions for UEFI made problems start. The partition label needed to be gpt (guid partition table), and the boot drive to fat32. – underscore Nov 30 '15 at 8:56

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