Booting a GUID disk on PowerPC Macs

Discussion in 'PowerPC Macs' started by LightBulbFun, Apr 5, 2018.

  1. LightBulbFun macrumors 68000

    LightBulbFun

    Joined:
    Nov 17, 2013
    Location:
    London UK
    #1
    I Just made a very cool discovery while playing around in OpenFirmware on my G5 Quad that I think is worth sharing

    which is that its OpenFirmware implementation can read disks with GUID partition schemes!

    after discovering this I quickly cloned Leopard onto a GUID disk and I was able to boot from it :D (so much for people saying PowerPC macs can only boot from Apple partition Map! :p )

    this is very good news especially for anyone who has a larger then 2.2TB drive that they wish to use in their PowerPC Mac as their startup disk (as APM only works properly with drives bellow 2.2TB)

    however I suspect that this functionality is only available on the very last (Late?) 2005 PowerPC Macs, ill be testing more of my PPC systems for GUID boot-ability and updating this thread as I do :)
    upload_2018-4-5_18-20-40.png
     
  2. Eriamjh1138@DAN macrumors 6502a

    Eriamjh1138@DAN

    Joined:
    Sep 16, 2007
    Location:
    BFE, MI
    #2
    So how is this useful to us? It’s cool, but... ?
     
  3. G4fanboy macrumors regular

    Joined:
    Mar 9, 2013
    Location:
    Andalucia Spain
    #3
    Your next goal could be achieve that on Tiger. :D

    It would be great if it works also for G4.
     
  4. LightBulbFun thread starter macrumors 68000

    LightBulbFun

    Joined:
    Nov 17, 2013
    Location:
    London UK
    #4
    but what?... :confused:

    Biggest thing this enables someone to do is allow them to use Drives bigger then 2.2TB as their boot drive (Apple partition Map does not work properly on volumes bigger then 2TiB/2.2TB), it also means if you have say Leopard on a broken intel Mac/on a HDD from an intel mac that you need to boot up for some reason and all you have is a 2005 PowerPC mac then you can do so :) )

    this is a Low Level Firmware thing the OS does not really come into play much here as long as it supports GUID/GPT it will be fine (which 10.4.11 does so I suspect tiger would boot up just fine, But I will test tiger at some point to be sure)

    as for G4s I tested it on my Late 2004 iBook G4 which does not read GUID volumes so that machine is out, but My 15 inch PowerBook G4 DLSD happily read the GUID volume and booted from it, I still need to test my 17 inch DLSD for GUID/GPT compatibility (I also Have a Early 2005 PowerMac G5 7,3 that I will test GUID compatibility on, so I can figure out exactly when Apple added GUID support to PPC macs/OpenFirmware so far it seems to be 2005 PowerPC macs only, I want to figure out if early 2005 PowerPC macs support GUID/GPT or if just the very last Late 05 PPC macs like the DLSD/PCIe G5s support GPT/GUID)
     
  5. eyoungren macrumors Core

    eyoungren

    Joined:
    Aug 31, 2011
    Location:
    ten-zero-eleven-zero-zero by zero-two
    #5
    ????

    It would be useful to me. It would allow me to use my 4TB GUID formatted secondary drive as a boot drive. Right now I have to stick with a 1TB APM formatted hard drive.

    That's how it's useful. :)
     
  6. Eriamjh1138@DAN macrumors 6502a

    Eriamjh1138@DAN

    Joined:
    Sep 16, 2007
    Location:
    BFE, MI
    #6
    So if I have a partitioned drive, all of the volumes are formatted as GUID. Then I can boot intel and others can boot PPC.

    That’s useful.
     
  7. weckart macrumors 601

    Joined:
    Nov 7, 2004
    #7
    Indeed, it is only the latter PPC models that had that ability. This was discovered at the time but somehow stayed under the radar. I checked out this discussion when seeing if I could resize/create/delete an APM volume on the fly and found this (see reply sphns on April 10, 2006 - 8:46pm )

    http://web.archive.org/web/20070509...om/tips/cli/nondestructively_resizing_volumes

    I think there might also have been something on it on MacOSXhints but my memory is a bit fuzzy.

    As for the resizing thing, two applications VolumeWorks and iPartition both do the job but nothing via diskutil, sadly.
     
  8. LightBulbFun thread starter macrumors 68000

    LightBulbFun

    Joined:
    Nov 17, 2013
    Location:
    London UK
    #8
    Very cool :)

    as for the Resizing thing Late versions of DU in Tiger (I know 10.4.11 can) and leopard+ can non destructively repartition/resize APM HFS volumes as long as they dont have Mac OS 9 Drivers installed :) (if you have Mac OS 9 drivers installed then it gets a bit tricker and I just use linux if i have to resize/partition a Volume with Mac OS 9 drivers installed)
     
  9. weckart macrumors 601

    Joined:
    Nov 7, 2004
    #9
    Yes, I knew this. Sadly, when I need to resize/move/delete there are always classic MacOS volumes involved. FWB Toolkit will resize volumes but only HFS volumes.
     
  10. vddrnnr macrumors member

    vddrnnr

    Joined:
    Jan 23, 2017
    #10
    Hi all,

    Using GUID also has another benefit you can create different partition types
    not only HFS because APM does not support the others, and modern OSs support GUID
    for sure.
    This way you can create EXT3/4 and FAT32 volumes without limitations which helps to store data
    in other partition types and make them accessible on OSs which do not support HFS.
    This will also help dual booting... I think.

    Best regards,
    voidRunner
     

Share This Page