Grub2 Arguments to Select GPT or MBR
Fedora Installation Settings
The purpose of this section is to provide a known workaround to the problem described in Red Hat Bugzilla – Bug 755232.
The problem is that of ending up at a Grub command line after upgrading, and not knowing what to enter to be able to continue and boot the newly upgraded machine. The cause is related to updated anaconda settings designed to stay current with advancing hard drive and BIOS or EFI technologies. Unfortunately, some older BIOS versions cannot boot to a GPT partitioned disk, but the new anaconda settings default to that configuration, thus making the machine unbootable after Fedora version upgrade.
The Workaround
1. Display the old grub config file with "cat (hd0,msdos1)/grub/grub.conf" command.
2. Enter the command "linux /vmlinuz-3.1... <arguments from the grub.conf>"
3.
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Essentially an older BIOS needing an MBR partitioned disk to recognize any of its partitions as bootable. These BIOS versions will not boot from with a GPT partitioned disk.