booting off GPT partitions

Andriy Gapon avg at
Wed Jan 27 17:18:07 UTC 2010

on 27/01/2010 18:45 Dan Naumov said the following:
> Hey
> I was under the impression that everyone and their dog is using GPT
> partitioning in FreeBSD these days, including for boot drives and that
> I was just being unlucky with my current NAS motherboard (Intel
> D945GCLF2) having supposedly shaky support for GPT boot. But right now
> I am having an email exchange with Supermicro support (whom I
> contacted since I am pondering their X7SPA-H board for a new system),
> who are telling me that booting off GPT requires UEFI BIOS, which is
> supposedly a very new thing and that for example NONE of their current
> motherboards have support for this.
> Am I misunderstanding something or is the Supermicro support tech misguided?

Perhaps both :-)
It depends on what booting capabilities you need from your BIOS.
With FreeBSD we currently typically don't use "pure" GPT and use Protective MBR
and install real boot code into a special boot partition.  Protective MBR looks
like a "normal" MBR to BIOS, and boot code in Protective MBR is smart to find the
boot partition and hand off boot process to code in it.
This way you can almost have the best of both worlds, but with some limitations
(like multibooting).  I don't know what other OSes do or expect in this area.

Obligatory wikipedia link:

Andriy Gapon

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