Re: Initial Program Loader in Hybrid MBR/GPT

[Chris Murphy]

On Mar 1, 2013, at 10:37 PM, Knapper <address@hidden> wrote:
> 
> I understand how to convert the protective MBR to a hybrid MBR that BIOS 
> machines can read.

Unless the BIOS system firmware is buggy, and doesn't like GPT, then you won't 
need a hybrid MBR. Many Lenovo systems appear to dislike GPT disks, but there 
are others.



>  I am less clear about how to get a working Initial Program Loader installed 
> and configured to go on loading the rest of GRUB2.  Is this possible?  Does 
> the content of the IPL depend on the partition scheme/configuration?  If not, 
> can I create an MBR installation of GRUB2 and copy the IPL over to the 
> protective MBR?  If I have a /boot partition and a /boot/efi partition, the 
> MBR active flag should be set on the /boot partition while the GPT boot flag 
> should remain pointed at the /boot/efi partition, correct?

Use GPT only for starters, with a 200MB EFI System partition, and a 1MB BIOS 
Boot partition, and then additional partitions as needed for your systems.

When booted in BIOS mode, 'grub-install /dev/sdX' will place some code in the 
first 440 bytes of the PMBR, and the rest of core.img will automatically be 
placed in the BIOS Boot partition.

When booted in EFI mode, 'grub-install' will create a grubx64.efi file and 
install it on the ESP in /EFI/<distro>/.

At least the Fedora GRUB2 package, grub2-install will create a core.img with a 
prefix that shares the same location for additional modules and the grub.cfg so 
one grub.cfg should work with either boot method, although I haven't tested 
this.

Chris Murphy