GPT as default?

John Baldwin jhb at
Thu Apr 26 22:37:16 UTC 2007

On Thursday 26 April 2007 06:16:03 pm Scott Long wrote:
> John Baldwin wrote:
> > On Friday 20 April 2007 04:55:35 pm Maxim Sobolev wrote:
> >> Scott Long wrote:
> >>> Poul-Henning Kamp wrote:
> >>>> In message <f0am4t$mmk$1 at>, Ivan Voras writes:
> >>>>
> >>>>> Currently, the FreeBSD default is classic BSD partitions on top of 
> >>>>> MSDOS partitions, and there are a couple of inconvenient things about 
> >>>>> this arrangement:
> >>>> The BSD partitioning should be discontinued as fast and firmly
> >>>> as possible.  By all means go GPT.
> >>>>
> >>> An i386/amd64 bootloader needs to be written that can understand GPT.
> >>> My understanding is that the ia64 EFI/GPT loader has very few reusable
> >>> bits.
> >> It probably crazy idea, but I wonder if it's feasible to have 
> >> "mini-GEOM" layer in loader, so that it's possible to use existing GEOM 
> >> classes codebase there with little or no modifications.
> > 
> > The loader is the easy part.  boot1/2 is the hard one. :(  You need both 
> > EFI loader, and a non-EFI bootstrap to load a non-EFI loader that can grok 
> > GPT for the non-EFI case where we still want to use GPT.
> > 
> Are there real-world PC BIOS's that understand GPT but aren't EFI-based?

GPT looks like an MBR for compat reasons, so probably any BIOS will see the 
AA55 at the end and boot it fine.  However, the rest of the bootstrap has to 
know to ignore the fake MBR and read the real GPT.

John Baldwin

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