PureOS ISO (USB) unavailable for boot (EFI) on Mac OS X

Software PureOS
1

Goal

Replace OS X with PureOS on my old Mac. I essentially want to give PureOS a go and buy a Librem PC if it works out.

Issue

PureOS (pureos-8.0-live-amd64.hybrid.iso) doesn’t appear in the boot ‘drive’ choices when I restart my Mac, so I can’t boot from the ISO and run the installer.

Details

MacBook Pro specs

  • OS X Yosemite (10.10.5)
  • MacBook Pro (15-inch, Mid 2010)
  • Processor 2.53 GHz Intel Core i5
  • Memory 8 GB 1067 MHz DDR3
  • Graphics Intel HD Graphics 288 MB
  • Storage 256 GB Solid State SATA Drive

What I tried

  1. Downloaded pureos-8.0-live-amd64.hybrid.iso from https://www.pureos.net/download.html and checked the hash. All good.
  2. Flashed the ISO onto a 4GB USB using Etcher (on another Mac of mine).
  3. Unmounted and unplugged the USB.
  4. Inserted the USB into the older Mac specified above whilst it was off, then turned it on (with the Options key pressed), no PureOS boot option available. I expected to see a external media icon labelled EFI.

Just for comparison, I downloaded the Debain 9 live install ISO (debian-9.3.0-amd64-netinst.iso), and performed the same flashing process as listed above, and the older Mac successfully picked it up on boot. I know that PureOS is a derivative of Debian, so this has left me somewhat confused.

I also ran fdisk on the ISOs to compare with the Debian ISO (may or may not be useful):

$ fdisk  pureos-8.0-live-amd64.hybrid.iso 
Disk: pureos-8.0-live-amd64.hybrid.iso	geometry: 686/64/63 [2768960 sectors]
Signature: 0xAA55
         Starting       Ending
 #: id  cyl  hd sec -  cyl  hd sec [     start -       size]
------------------------------------------------------------------------
*1: 17    0   2   1 - 1017  84  32 [        64 -    2768896] OS/2 hidden 
 2: 00    0   0   0 -    0   0   0 [         0 -          0] unused      
 3: 00    0   0   0 -    0   0   0 [         0 -          0] unused      
 4: 00    0   0   0 -    0   0   0 [         0 -          0] unused 

$ fdisk debian-9.3.0-amd64-netinst.iso 
Disk: debian-9.3.0-amd64-netinst.iso	geometry: 589/16/63 [593920 sectors]
Signature: 0xAA55
         Starting       Ending
 #: id  cyl  hd sec -  cyl  hd sec [     start -       size]
------------------------------------------------------------------------
 1: 00    0   0   0 -    0   0   0 [         0 -          0] unused      
 2: EF 1023 254  63 - 1023 254  63 [      3760 -        832] <Unknown ID>
 3: 00    0   0   0 -    0   0   0 [         0 -          0] unused      
 4: 00    0   0   0 -    0   0   0 [         0 -          0] unused

I’m thinking that the PureOS ISO isn’t (U)EFI compatible, so this Mac hasn’t been able to pick it up on boot?

If anyone has any tips, please share and help me out - I’d love to get this working!

2

Hi,

I have been using PureOS on my Macbook Air 5.2 without any issues, everything works perfect. I have used dd command to create bootable usb drive in OS X and than boot with option key.

Indeed ISO is not (U)EFI compatible, it boots without EFI, I install OS without boot loader and later I install grub manually to efi partition.

3

Thanks sgomare :slightly_smiling_face:

I shall create a boot disk, in order to attempt booting from BIOS. I’ll post an update on here once I get around to it.

1 Like
4

Correction: I mean bootable USB drive

5

In order to wrap this up - I gratefully received a fantastically detailed response over on Super User, that helped me resolve this issue.

1 Like