I partitioned a USB flash drive as GUID and used it to install FreeBSD 10 for x86_64 off a DVD on a MacPro1,1. I was able to select the installation DVD as my startup disk in Mac OS X just by going to System Preferences > Startup Disk and selecting it. But OS X (I tried SL, ML, and Mavericks) can't read FreeBSD startup partition on the flash drive because it's formatted as FreeBSD_UFS. As a result, I can't select the FreeBSD partition as my startup disk.

I also tried this: sudo bless --device /dev/disk4s2 --setBoot --legacy followed by a restart (disk4s2 is the FreeBSD partition of course). It just booted back into OS X.

I tried holding the option key at startup. The FreeBSD partition was not an option. On a PPC Mac, it is an option, but of course I need the PPC version of FreeBSD to actually boot from it. On a PC with a BIOS, I can easily set the boot device to the flash drive in the BIOS settings. Unfortunately, it's not that simple on a Mac to change EFI settings.

I'd like a solution that doesn't involve permanent modification of the host machine. Maybe I can install a boot manager that can boot into FreeBSD that OS X will recognize as a startup disk on another partition on the flash drive. I don't know the best way to do that.

  • 1
    is unix.stackexchange.com/questions/151968/… any use to you?
    – Tetsujin
    Jan 9, 2015 at 8:39
  • @Tetsujin I tried that a long time ago and actually left a comment there because it wasn't working. Regardless, that would require installing stuff on OS X, which I don't want to do this time. I want a USB stick with FreeBSD that I can plug into any Mac and boot from, all in firmware and independent of the OS.
    – sudo
    Jan 9, 2015 at 8:57
  • I just now tried repartitioning the flash drive on my Mac to get the EFI partition back then reinstalled FreeBSD, this time leaving the EFI partition intact. Didn't work.
    – sudo
    Jan 9, 2015 at 8:58

1 Answer 1


It appears to be quite complicated to boot an OS other than Mac OS from USB. See this thread on Ask Ubuntu for discussion on someone trying to do similar.

I know you don't want to install anything on the host system, but installing rEFInd or the older rEFIt may get you there. In that aforementioned thread a few people mentioned that once they had it installed a non-Mac OS USB drive would be listed as bootable from the bootloader menu.

  • I think rEFInd sometimes working is the best we can do, unfortunately. Thanks.
    – sudo
    Jul 1, 2015 at 17:46

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