GPT - (last) call for action

Marcel Moolenaar xcllnt at
Sun Jun 10 18:09:05 UTC 2007

On Jun 10, 2007, at 10:52 AM, Matthew Dillon wrote:

> :Technically speaking, the MBR can only have a single partition of
> :type 0xEE that covers the whole disk. This is to protect the GPT
> :from MBR-specific tools that do not know about the GPT. This is
> :not a bootable slice by definition.
> :
> :Practice is different. To support bootcamp on Intel-based Macs,
> :the MBR will have real partitions that mirror GPT partitions or
> :otherwise describe partitions outside the GPT controlled area.
> :These can be bootable partitions and the protective partition
> :(the one with type 0xEE) will not cover the whole disk anymore.
> :
> :The nasty part is keeping MBR and GPT partitions in sync, so it
> :may be better to have the MBR partition fall outside the GPT
> :controlled area. This can be done because the GPT header contains
> :the LBA of the first and last sectors on the disk that can be
> :assigned to a partition. You can free up space for MBR partitions
> :after the primary GPT table by adjusting the first LBA. In the
> :MBR partition you can put a GPT aware boot loader that uses the
> :GPT to find the real partitions...
> :
> :--
> :Marcel Moolenaar
>     In the bootcamp approach, is the GPT (0xEE) slice the first slice,
>     and the bootcamp slice the second slice?  I'm assuming it is.  Do
>     they mirror a GPT partition or do they use the uncontrolled area
>     approach?

I seem to recall that the 0xEE partition is not the first, but rather
the second or third. It would make sense, because it has no function
other than to have the disk appear used. Bootcamp uses the mirroring

Marcel Moolenaar
xcllnt at

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