[parted-devel] [PATCH] GPT & BIOS Boot partition

[Robert Millan]

On Fri, Feb 22, 2008 at 10:37:29AM -0800, H. Peter Anvin wrote:
> Robert Millan wrote:
> >On Thu, Feb 21, 2008 at 03:57:03PM -0800, H. Peter Anvin wrote:
> >>Is there any specification for this?
> >>
> >>This seems like a specific boot GUID, but is there any documentation as 
> >>to handover protocols, cross-OS support, etc; or is this a "Grub2-only 
> >>standard"?
> >
> >GRUB goes its own way, just like on DOS labels, and extends this with info
> >about which drive contains /boot/grub/, etc.  Otherwise, it can work the 
> >same
> >as on "standard" MBRs for DOS labels (same entry point, etc).
> >
> >You might be interested in:
> >
> >  http://aybabtu.com/mbr-gpt/
> >
> >So, setting the "boot_bios" flag on GPT is essentially the same thing as
> >setting the "bootable" flag on a DOS label.
> >
> 
> Yuck, this is a total mess.  It's not a "bootable" flag, then, it's a 
> "I'm Grub" flag.

Not really.  For example, you can do:

  grub-install /dev/sda3	# this won't touch your MBR!
  dd if=mbr-gpt of=/dev/sda

and it works.  There's nothing GRUB-specific in it;  the MBR just loads the
first sector of /dev/sda3 at 0x7c00, sets appropiate %dl register and jumps
to it.  As long as the code in /dev/sda3 knows what to do on GPT, everything
should be fine.

-- 
Robert Millan

<GPLv2> I know my rights; I want my phone call!
<DRM> What use is a phone call… if you are unable to speak?
(as seen on /.)