Resolved Partition and bootloader questions

Discussion in 'PowerPC Macs' started by GameX, May 27, 2014.

  1. GameX, May 27, 2014
    Last edited: May 29, 2014

    GameX macrumors newbie

    May 27, 2014

    I had a PowerPC in my shed, it was there for about 8 years, and probably was never used much. It's a 1999 model, a PowerPC G3, slot-loading. It has 512MB of RAM (One empty slot), and a 120GB hard-drive, pretty sure it was upgraded! Also has a 400 MHz CPU.

    I did used Mountain Lion for about a year, for school iOS development, I'm used to it, but never had the possibility of testing an actual PowerPC. I quickly find out that I was really limited with this low-end machine, and the PowerPC architecture.

    I have a first question about partionning, I did this often on PC, with GParted; had trouble to partition my G3, using Disk Utility, it came with Tiger on it.
    For some reason, I cannot split a partition without erasing their content (and without warning!). That's no big deal, because there's nothing important on this drive, I just experiment.
    I believe that the problem is related to "Live partionning", which Tiger does not support. To partition the boot volume, I had to boot from the Tiger DVD, then partition, which wipe the chosen partitions... How can I avoid this? Which software would allow me to do it on PowerPC without this limitation?

    Next question, is related to the OS X bootloader. I believe it's called "BootX", but please correct me if I'm wrong.
    I've broke and fixed Windows/Linux bootloaders multiples times, and wish to understand more about the OS X bootloader, which I find a little confusing for now (I tried to install Lubuntu on the G3 - I succeeded by using all the disk space, but did not managed to install it next to OS X - couldn't install Yaboot).
    On my PowerPC, I notice when I hold the Option key, I have the disk selection screen, with a purple background and square boxes. When I first booted the Mac, I wasn't sure if I would saw this one instead:

    What's the bootloader shown above is, actually? Is this one exclusive to the Intel Macs, and is there anyway to get it on PowerPC (I would doubt it) ? What's the version of this bootloader? Additionally, what version of the bootloader (with the purple background, very similar to OS 9) do I have?
    On Windows there are NT Loader and BCD, what are the names for the OS X bootloader, is this always the same? I wondered if it was related to Darwin at all (I have Darwin 7 is believe), or it's unrelated and Darwin pretty much is the hybrid Mach/BCD kernel.

    Is the OS X bootloader breakable in first place? I wonder - NT Loader can easilly wipe GRUB bootloader for Linux (Which is easy to fix), can something similar happen to OS X, which would prevent the system from booting? How would you fix this? Like, if I installed Windows manually without BootCamp (on an Intel Mac of course), wouldn't the OS X bootloader get wiped, or without any consequence?

    I confuse a little the bootloader (BootX ?) and the OpenFirmware, which would be an equivalent to the BIOS...
    Not sure to quite understand this aspect, and I would love to.

    Sorry, that makes a lot of questions in one post.

    EDIT: I guess the answer is related to the partition scheme, the Apple Partion Map or GUID partitionning which Intel Macs use... They natively don't use MBR, so... ?

    Thanks for the explanation!
  2. Intell macrumors P6


    Jan 24, 2010
    Later versions of Tiger can preform a live non-destructive disk partitioning. However, if your disc has the OS 9 drivers installed on it, you cannot partition it without erasing all data on it.

    Mac OS X doesn't really have a bootloader. Everything is done through OpenFirmware or EFI, depending on the CPU architecture. Because it doesn't have a bootloader of sorts, it can't be broken. But you can break and even brick a PowerPC machine with the wrong OpenFirmware command.
  3. GameX thread starter macrumors newbie

    May 27, 2014
    Thank you for the very fast reply.

    As for the OS 9 drivers, are you referring to the checkbox, during the installation "Support for OS9", something similar?
    I did tested OS 9 on this machine (This was the only occasion I managed to try it, never had a PowerPC before), and it worked. I don't know how to verify it, but I would assume I have the OS 9 drivers (Because OS 9 work). Can I delete these (Wipe OS 9 ?), so that I could use live partitionning ?

    My goal would be to find a partionning or backup software, so that I could install Linux on it, without wiping the whole disk.

    Oh, so I would guess OpenFirmware is used for PowerPC (I did tried to boot in it with Cmd-Alt-O-F, it worked), and EFI, for Intel Macs if I'm correct. I don't know the use of OpenFirmware, and what it can do, however.

    Do you have an example on how to break the firmware, I'm curious (Mostly, I wonder this, so I could fix these problems later, if they occur. Bricked, it's bricked and sometimes not fixable).
    So what was I referring to, when I talk about "BootX" ? Will do a Google Search in first place. ;P

    Thank you!
  4. Intell macrumors P6


    Jan 24, 2010
    You can check if the OS 9 drivers are installed by looking in Disk Utility. Go to the Partition tab, you'll see a greyed out check box for them. If it's checked, they're installed. You cannot remove them without completely wiping the drive.

    A good backup program is Carbon Copy Cloner. It's powered by rsync and can make a mirror of the drive or a disk image of it.

    I'd rather not post a few commands that bricks a PowerPC Mac via OpenFirmware. Once it's bricked, it will chime, then do nothing. Not startup, not reset the PRAM, not go into OpenFirmware. Nothing. Only way to fix it is to replace the logicboard or the bootrom chip. Neat party trick.

    BootX or boot.efi on an Intell Mac is the thing that gets loaded by the firmware. That in turn loads and runs the kernel. Deleting or altering the BootX or boot.efi file makes a Mac not bootable until it is replaced or repaired.
  5. GameX, May 27, 2014
    Last edited: May 27, 2014

    GameX thread starter macrumors newbie

    May 27, 2014
    Cool, I will check that;

    I also heard about CarbonCopyCloner, I was about to try it, when I noticed it probably doesn't have a boot DVD (So that I could boot CCC from a DVD). But as long as I can edit the boot volume, that will be OK.

    I know about Rsync as well, although I never used it much, it's really powerful.

    I don't know about the use of the OpenFirmware command-line (it look like it doesn't have a lot of usable commands), but I guess I'll just Google it. I used Single-User mode several times however, so I'm familiar with UNIX.
    As for bricking, thanks for the info - I once bricked my Android phone when I was a novice, managed to recover it, then I became more advanced and used to flashing ROMs and stuff. But sometimes as you said, bricking is permanent.

    I will try CarbonCopyCloner, and will tell you how it goes!
  6. GameX, May 28, 2014
    Last edited: May 28, 2014

    GameX thread starter macrumors newbie

    May 27, 2014

    I successfully installed Linux next to OS X, althought I partionned my disk before I even installed Tiger, so nothing was wiped.
    I figured out that the Bootloader "Yaboot" had to use his own 10MB partition, this is different from GRUB (I would assume that it's simply because of the partionning scheme that's for PowerPC and not MBR).

    Tried CarbonCopyCloner, it look great - I took a full DMG image of my OS9 partition for testing, I will later format it on purporse, and try to restore it.

    I have a few more questions, still related to the partitions and "bootloader"; I opened Gparted from Linux, to observe the partition map of the drive. I was a little confused when I installed Linux, because it saw partitions that weren't listed in Disk Utility. When I started up Gparted, this is what I saw (Yeah, there's a lot of unused space, apparently, Disk Utility did that, would be interesting to know why):

    Why on Earth are there EIGHT partitions on the drive listed as unknow? :confused:
    I would really like to know what are they, actually. I suspect one of them is the OpenFirmware itself (If that's possible, if it's not on the motherboard instead. I honnestly know pretty much nothing about OpenFirmware yet, except that it's the BIOS equivalent on PPC) ?

    What would happen if I delete/format one of these? =P
    (No worries, I won't. If one of these really is OpenFirmware, or anything critical to the boot process, which I suspect, I could do serious damage - or even brick?)

    Second question, would be the drive selection screen that shows up when holding the Option key. For me, I have the screen with a purple background with square listing the drives.. Does this screen have a specific OS X name I should know?
    Can I change the background color (Doubt it...) ?
    Maybe changing the disks images (I ask this, because my Linux drive has a Tux next to it, so)?
    I'm a Linux guy, so I try to customize as much a possible, although for sure it is limited/a LOT more difficult on Mac. :p

    Third question:
    I noticed, mostly on a Linux desktop, that the iMac is something beeping, probably unrelated to system volume. These are short beep, high-pitched. 2 beeps per seconds, during 5 to 10 seconds. They come and go.
    What do they mean? Overheating? I've read this may be a RAM problem as well (It's a 1999 Mac, so maybe).

    Thank you, I appreciate it!
  7. Intell macrumors P6


    Jan 24, 2010
    Those extra, small partitions at the start of the drive are the OS 9 drivers. You can remove them, but then OS 9 won't be able to boot from that disc until they are reinstalled by Disk Utility. OpenFirmware lives on a 1MB chip on the logicboard. You cannot change the boot disk selection screen. Slot-loading iMacs generally don't overheat. When they do, they freeze and stop working. If the system boots and is stable, then the ram is likely good.
  8. GameX thread starter macrumors newbie

    May 27, 2014
    Nice, that was really helpful.

    I think I will attempt to delete them, and try to restore the OS9 drivers from Disk Utility, I'm still experimenting.
    I might as well try and resize a few partitions from GParted (Which always was my partionning tool of choice), and see what that does, I don't have important stuff on the drive (Using another utility is probably a bad idea, but let's see if the partitions survive the shrinking at all through GParted rather than Disk Utility =P ).

    I find it akwards to store the drivers on 8 different partitions, but anyways. =P
    (Why 8 and not just 1)

    I wonder, about the boot disk screen, the Linux drive does have a Tux as it's picture, was it added by Linux itself during the install (So in some way, the Tux icon would be changeable :/ ), or might a well be planned from the start, hardcoded in the firmware. If you say so. ;)

    About the RAM, the system does have difficulty multi-tasking smoothly, mostly when iTunes is open. Web browsing, even with TenFourFox optimized for G3 is "OK" but long.
    I would assume it's OK, guess it's just the low 512MB, or the G3 that obviously show his age.

    Thank you again.
  9. Intell macrumors P6


    Jan 24, 2010
    Tux, the blue X, and the orange 9 all come from the blessed boot file. Tux is stored in the yaboot bootloader, the X is in BootX, and the 9 is in the System file. I do not know of any way to alter that image.
  10. GameX thread starter macrumors newbie

    May 27, 2014

    You obviously really know what you're talking about. :)
  11. GameX thread starter macrumors newbie

    May 27, 2014
    Final question, booting related, before marking the thread as solved ? =)

    I already used "BootXChanger" on a Intel Mac to change the boot logo, it worked - did not tested it yet on PowerPC, but seems there's an older version that would work.
    If you know about it, I would like to know what BootXChanger actually does, to change the boot image - if it's changeable manually, without the use of a software?

    Might be a complicated process.

    Thanks for all your answers, that really helped. ;)
  12. Intell macrumors P6


    Jan 24, 2010
    The older version of that software does work on PowerPC Macs. But due to limitations of OpenFirmware, it can only be 256 (I think 256 or maybe 16/32) colours and cannot be very big. It also cannot change the colour of the grey background. I read about how that works, it can be done manually. But it requires great knowledge of a hex editor and the inner workings of bit image manipulation. One last thing with it, if you set an image on a partition, then boot from any other drive or partition, the partition with the set image will revert back to the default Apple logo. It does not stick like it does on Intell Macs.

Share This Page