[SeaBIOS] GPT disks in a BIOS world

[Fred .]

On Tue, Jun 5, 2012 at 5:21 AM, Kevin O'Connor <kevin at koconnor.net> wrote:
> 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.

But does GPT disks even have a MBR?
Isn't the GPT a replacement for MBR?
If the disk doesn't have any MBR, does the BIOS load the first sector of GPT?

>
> 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
>
> _______________________________________________
> SeaBIOS mailing list
> SeaBIOS at seabios.org
> http://www.seabios.org/mailman/listinfo/seabios