Leopard on MBR DualBoot

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(for burning issues see tips at end)

note: test the Knoppix and see if you can boot up a console with external storage support. You'll need to be able to backup your MBR record(just 512 bytes) In this case check out knoppix, a linux live-cd known to support external drives(notably usb, usbsticks, floppy disks etc, you can even do network storage as knoppix automates dhcp but i dont cover this)


[edit] What Linux commands will be done with Knoppix CD

just 3 commands and should take no more than a minute: fdisk, cfdisk, dd ?What these commands will be used for: Backing up 512 bytes (the MBR sector), be it a floppydisk, usb drive.. and the same Mbr record. (this means before the pre installation and post installation)

note:If you do the Mactel MBR install on an AF type partition(primary or logical), you won't lose your other partitions(&the filesystems on them), but you may lose the harddrive's 0-446 bootcode and is easily restorable with the backup.

[edit] How safe is this?

You tell me! give me feedbacks. I believe this is very safe if you carefully follow its instructions. (but always make a backup anyways)

[edit] How easy is this?

If you can boot your system with one of those disks(kalyway's, toh's, Uphuck's,idebene, and able to type a few linux commands and follow instructions you should be on your way. You must know at least a few basics: how the first sector of your ata drive is organized, and if any bootflags need to be addressed(I'm assuming you know this since Dualboot geeks have this culture that you must know at least this)

[edit] What are the limits?

Knowing if your hardware works with your Mactel dvd's kernel as well as the default Harddrive kernel(mac install)(if dvd boots into installer, doesnt mean the installed kernel on HD will be able to at boot into gui even after using the boot_v8 fix described below), and if any kernel driver patches may be an issue with the particular HD kernel in use. .

I dont cover on how much disk space you should have. I believe 5-6 gigs should be minimum set aside. I also dont cover on how you can shrink any current filesystems and partitions in order to make space for a mactel install. .

[edit] The MBR format


Short summary.. 512 bytes (the entire first sector of the drive is the MBR, a sector is 512 bytes of course) Partition table resides at offset from sector 0 of drive- this offset is 446.

note: dont let this short summary scare you dont need to know anything more complicating than this: that to address this little 512 bytes from your knoppix livecd would be just to restore the first 0-445 (inclusive) bytes your Mactel DVD installer touch. Your Mactel DVD installer will touch your partition table(sector bytes 446-512) (I guess the mactel people are trying to find ways to fix this and is probably difficult to track down where in the installer is doing this)

[edit] What's the purpose of the Knoppix CD?

To create the AF type partition into the partition table. (I'm not sure how your Mactel installer may touch the partition table). This does not make a filesystem on the harddrive. You will do that using DiskUtil from Mactel installer.

The Knoppix CD will also be used because the MacTel DVD installer touches bytes 0-445 of the MBR. (I do not think yet any Mactel installer has fixed or prevent their install from tarnishing this part of the drive on MBR installs, it would be great if this can be prevented)

[edit] Pre-Install: Setup your bootmanager with boot_v8

Download the boot_v8 efi package on your current system (~250kb), extract package and copy the boot_v8 file for your boot manager

Linux+grub scenario eg: On Linux machines, grub is very popular, here's how it can be done -copy boot_v8 to /boot

-Add to grub.conf file

  • if hd0,0 is seen by grub as your harddrive's partition containing your /boot/grub.conf file and /boot is a directory on that partition

(hd0,0 is grub's form of expressing the first partition on the first harddrive it detects) (the harddrive expression for boot_v8 in grub.conf should be same as your other kernels)

title Darwin
kernel (hd0,0)/boot/boot_v8
  • to see your mountpoints on linux use mount cmd

-If /boot is a mountpoint for your first partition on your first harddrive your entry to grub.conf file may need to be like this

title Darwin
kernel (hd0,0)/boot_v8

Windows scenario

*Feel free to add.. ntldr.ini 

- I dont know the full instructions but boot_v8 can be loaded from xp's boot loader, as well as vista's i believe

*<feel free to add tips here for syslinux/etc for other scenarios linux-distro types etc..>

[edit] Mactel Install

Mactel Installs can be done using the following scenarios.

ATA drive: 2 Primary partitions (MBR paritition table) + 1 Primary Partition for 'Mactel'

(note: GUID-partition tables HD's do not apply!) (this works)

ATA drive: x Primary partitions+<1>Logical for 'Mactel' (if you're stuck to this setup I **""know"" for a fact that Logical AF partition setups can boot with a cd-rom using rd=disk<a #>s<a #> on mach_kernel bootline.)) (get back to me if you're able to bootstrap mach_kernel without cd-rom rd= if mactel goes on logical partition type)

*Feel free to add other scenarios here, eg: if this boot_v8 works on your internal SATA or SCSI drive which I do not have..

[edit] Step 1: Setup your 'AF' partition type and Backup MBR

Knoppix CD boot to Console (before booting, plug in any external usb drives or usb stick, etc you want to backup your MBR to)

issue- "knoppix 2" on bootline (this brings us to console, we dont need X loading)

once in console

stp- make partition type in mbr --

command: cfdisk <enter>


command: cfdisk <known device> <enter>

(cfdisk opens first default drive of system, if you dont want this, you need to know the device name of hard drive)

probing for unknown device name command: #fdisk -l 'lists drives on your system (if targetted partition is passed 4th primary partition, this means you're using logical partition type, I do not know if boot_v8 supports logical partitions at this point)


fdisk -l

can show /dev/hda1<filesystem type:linux ext2>, /dev/hda2<filesystem type: linux swap>, <empty space partition>

in this scenario /dev/hda3 doesnt show at this point until a partition table entry is made and can then be listed with fdisk

create partition on free space (cfdisk is now loaded should show empty space, making empty space is beyond this article) use program and create an 'AF' partition type for empty space (marking AF partition type does not create any HFS filesystem on partition but adds an entry in MBR, somewhere between bytes 446-512 on sector 0) -select 'write' in cfdisk menu by typing 'yes'<enter> -then quit program

stp- backup MBR onto external media By default Knoppix makes any usb drive partitions that it finds in its /etc/fstab mounting rule table, so it is convenient to mount your drive at a mountpoint by simplying typing..

mount /mnt/<relevant mountpointname>

The way to do it more fully on non-knoppix or generic linux is: make mountpoint (a directory)

mkdir /mnt/<a dirname>



mount -t <filesystem_type> /dev/<devicepartition_that contains filesystem> <mountpoint>


for ext3 filesystem residing on a usb device partition (3rd primary partition of drive) and /mnt/fbar as its mountpoint..

mount -t ext3 /dev/sdb3 /mnt/fbar

stp- backup mbr

dd if=/dev/<ata drive devicename> of=<mountpoint>/<some filename> bs=512 count=1

bs is for bytesize.. be sure to include count=1, you dont want need anything more than the MBR

eg:#dd if=/dev/hda of=/mnt/fbar/myhdaMBR.bin bs=512 count=1

now unmount mountpoint to be sure drive is synced

umount <mountpoint>  eg:#umount /mnt/fbar


umount /dev/<bakup devicename> eg:#umount /dev/sdb3

-stp shutdown system (knoppix should release dvd before shutting down power)

[edit] Step 2: Start up your Mactel Installer DVD

DiskUtility Once your installer boots into the gui, use any prompts and then to the top menu bar to open DiskUtility.

DiskUtility should list your partition map. (you may wish to take down the devicename of your AF partition at this point in case boot_v8 does not work for you and are stuck booting into your new Mac using rd= on cd's bootline)

-The AF partition would at first when DiskUtility is started be listed as if it was formatted but it isn't -We dont need to change any partition scheme since we do not want to touch the partition table and damage our other filesystems

format your 'AF' partition to Mac's HFS+ journaled case-sensitive (best one avail).

-Give it a Volumename if need be and apply any changes. Now exit Diskutility program. -Follow installation prompts, you should now be able to select that partition you formatted for installer. -Let installer do its copy part

  • Be on standby on your machine's reboot, otherwise any failure might cause your bios to go reset on many cycles which is not good for the machine's hardware(it has happened to me)
  • if you're preparing your disk to create a new spare partition on an already full drive, see my tips at end

[edit] Step 3: Post-install Intervention: Restore MBR and copy boot_v8 for Boot Manager

-Mactel installs may place poor bootcode at the head of the MBR, so we need to fix this. It's simple we'll restore our bootcode using Knoppix.

Use Knoppix CD' -type 'knoppix 2' on bootline (plug in your bakup external media before booting knoppix)

-mount bakup media filesystem and issue restore command

eg:#dd if=/mnt/fbar/myhdaMBR.bin of=/dev/hda

(note: for real geeks we can argue that we aren't restoring the partition tables as that would not have been touched by mactel installer ;-)

[edit] Final step

Ok reboot now, you should have your Boot Manager already setup and have Darwin selectable

Errs: if boot_v8 cannot work for you, perhaps some other tricks can.. feel free to add your workarounds here..

*bootv8 alternatives:

*feel free to add some if need be

? does anyone know if copying boot_v8 directly to the boot record (bytes 0-446) works? as a fix if someone just wants to have mactel on a single partition on the drive? (cat boot_v8 > /dev/hda ) . .

[edit] tips:

About burning some hfs+ hybrid images: if you're stuck on using windows, I've used transmac to burn my dvd isos,dmg files without issues. (the mactel installer images I dont believe pose this issue, but this info may be helful for other things for backup/restore from a windows station)

Preparing Disk for free partition space on a full Drive

<can add your link and title here> 

NTFSresize on Linux (do a defrag and scandisk on your Windows before)

resize2fs (you can shrink ext2/ ext3 MBR partitions with linux liveboot cds)

BootFlags? Anybody knows at this point if boot_v8 requires or if there are problems on running Mac system 'NOT to have bootflag set? . .

*Feel free to add more tips here, or references to other tips.. . . .

This page was last modified on 24 November 2010, at 03:36.
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