GPT as default?

Dag-Erling Smørgrav des at
Fri Apr 20 17:15:24 UTC 2007

Ivan Voras <ivoras at> writes:
> Many systems (including MacOS X and Solaris) are moving to GPT
> partitions (, mostly
> because they don't have the above limitations. My proposal is that we
> deprecate BSD labels and move to GPT in 7.0 (or more correctly, if the
> stars were to be benevolent on us, on the new systems that are
> installed by the new GPT-aware installer :) ).

Not unless geom_gpt receives considerable attention.

Currently, it is not even possible to list the GPT, let alone create
new partitions, if one of the partitions is open.  GPT can not be the
default partitioning scheme until this is addressed.

> The second is more serious: FreeBSD boot code cannot boot from a GPT
> partition.
> Part of the problem is that GPT uses GUIDs for distinguishing
> partition types, so the current code that recognizes various partition
> types (Linux, FreeBSD, NTFS - the famous "F1" prompt) may need to be
> thrown out since each GUID is 16 bytes long and AFAIK there's only
> about 300 bytes in the MBR for the boot code.

DOS partitions normally start on a cylinder boundary, even though
cylinders no longer mean anything.  This means there is plenty of
space for code and data between the MBR and the first partition.

I don't know if this is also the case with GPT.

> Now, the problem is - is someone with enough assembler knowledge
> interested in implementing a GPT-aware boot loader? :)

Capable, yes.  Interested, perhaps.

Dag-Erling Smørgrav - des at

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