Multibooting Windows/OSX on guid.

Long waited solution 😀

To make it , need to use gptsync, i found binary for linux (from apt-get isntall refit)

Good luck with finding out binary for osx.

Ok, so, u need to sync your gpt table to mbr table, the only limitation – mbr can have only 4 entry for partitions,

and first entry will be used for guid protective entry (partition with type 0xEE)

So, u will have three partitions to install windows.

However installing windows will overwrite mbr boot sector (where u installed boot0),

so need to reinstall boot0 after it

So, u can have up to 128 guid partitions, but only first three (excluding efi partition)

will be windows-compatible

If windows knows about gpt (not xp, 2003sp1 knows guid e.g., or 64-bit xp, or vista),

then u can use other gpt partitions

for data,  u still can’t boot windows of it(diskXs2-4 – bootable for windows, diskXs5+ – not bootable).

pc_efi is able to boot windows bootloader from partition (chainloading).

Good luck.

Users posted gptsync for OSX in comments.

P.S. binary gptsync for linux I found – gptsync
P.P.S OSX will see drive ad guid still, after any changes to guid partition table, u need to resync it again.


  1. kocoman
    December 1st, 2007 | 11:59 am

    A lot of piggybacking between gpt/mbr. but its cool.

    Can you resize GPT’ed NTFS/FAT partition with disk utility etc? Also Disk Utility doesn’t support Moving partitions once resized.

    Next is RAID booting on GPT??

  2. December 1st, 2007 | 1:40 pm


    u know this error?

    using efi 7.1

    greetz =)


  3. Brywalker
    December 1st, 2007 | 3:07 pm

    I do like this, but I am wondering if this should be a separate project. IE: PC_EFI that strives to be IDENTICAL to the actual Mac hardware, and one with chainloading, etc. Personally, I would love to see PC_EFI that will allow hardware profiles to be added so there doesn’t have to be any kext modification, IE: the x1600 v6 EFI.

  4. kbe
    December 1st, 2007 | 3:36 pm

    Dear netkas! What about 200M EFI partition – now it’s only useless waste of a disk space… 😉 Have you any plans for it in future?
    Проще говоря, не предполагается ли вынести часть EFI модулей туда, чтобы они занимались своим делом, а не лежали в папке Extentions?.. 😎

  5. sweec
    December 1st, 2007 | 3:44 pm

    No way to enable BOOT CAMP by PC_EFI? That’s what make you approaching MAC, I guess.

  6. SA22C
    December 1st, 2007 | 4:17 pm

    f41qu3 :

    That error occurs on my machine every so often, but goes away after a restart. It has to do with the EFI loader properly detecting the system clock, but I don’t know what the fix is if it’s happening all the time.

    December 2nd, 2007 | 10:01 am

    i dont really understand what we need??

    So we have to install refit?
    Sync it
    install windows
    redo boot0 and we are good?

  8. phnix
    December 3rd, 2007 | 6:22 am

    I’ve compiled an os x binary of gptsync from the refit project. Seemed to work from the Leopard install DVD (can’t sync the partition map on the drive you’re booted from).

    Currently testing/installing, seems to have worked.

    RS Link:

    gptsync and showpart in there. should at least work on leopard, unsure about earlier.

    December 4th, 2007 | 12:13 am

    i didnt need to use gptsync. vista works fine now

  10. netkas
    December 4th, 2007 | 12:21 am

    how ?

  11. phnix
    December 4th, 2007 | 10:31 pm

    Just as an FYI using gptsync from the leopard install disk (the one I’ve posted) has worked for me, and I’ve got dual-booting WinXP 32 & Mac OS X.

    Is there any way to have the list of volumes show up for a brief time before booting without having to mash the F8 button? Would also be nice to be able to decide under OS X or other operating systems which OS to boot next.

    That said, I’m not complaining. What you’ve done netkas is quite awesome.

    Re netkas on i am…me: I think he’s using 64-bit versions of Windows, or other ones that are GPT aware. There’s a thread on forum.insanelymac where he describes what he’s using.

  12. sponkemonke
    December 14th, 2007 | 4:20 am

    gptsync cant detect GUID and MBR partition tables even when booting off a DVD. Is it because the harddrive is a SATA?

  13. b8man
    January 23rd, 2008 | 7:06 pm

    Hi gents,

    I ‘v got succes by tripplebooting OS: Leopard, windows XP, Linux.
    I will share my “how to” as soon as it will be ready,

    see you mate

  14. el último danzarín rostro
    January 24th, 2008 | 11:53 pm

    can i setup a dual boot using ubuntu instead windoze using this solution?

  15. alvin777
    October 18th, 2008 | 3:42 am

    Hi. Netkas. Pystar has setteled with Apple, you must at least try to settle with both Apple and/or Pystar. I think they’ll be making a software product out of this mess, look at their codes that’ll surely defeat the hackintosh for good or for a long time.

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