[SeaBIOS] GPT disks in a BIOS world

[Kevin O'Connor]

On Mon, Jun 04, 2012 at 07:11:30PM -0700, Ralf A. Quint wrote:
> At 03:36 PM 6/4/2012, Kevin O'Connor wrote:
> >On Mon, Jun 04, 2012 at 03:33:05PM +0200, Fred . wrote:
> >> http://mjg59.dreamwidth.org/8035.html
> >>
> >> Does SeaBIOS support GPT disk labels?
> >> Does SeaBIOS understand GPT disk labels? Is it aware of GPT?
> >
> >This is a common misunderstanding of the BIOS.  The BIOS doesn't do
> >anything with partition tables at all (at least according to the
> >available specs).  Thus, the BIOS doesn't care if it's a legacy
> >partition table or a GPT partition table.
> 
> Excuse me, but isn't it the BIOS that after POST is initiating the
> boot process from the active partition?

Not quite.  The BIOS loads the first sector of the hard drive (ie, the
MBR) into memory and runs the code found there.  It cares nothing
about the partition table.  It's quite common for the executable code
in that first sector to analyze the partition table, load yet other
code, and then jump to that code - but that activity is outside the
BIOS and is easily upgradable.

At least, that's what SeaBIOS does and what the available BIOS specs
call for (and what every boot loader I've seen expects the bios to
do).  But, who knows what crazy things various comercial BIOSes do.

-Kevin