On Apr 18, 2012, at 12:16 PM, John R Pierce wrote:
ah, I can't see anywhere in the BIOS for this SuperMicro X8DT6 mobo where to enable EFI, I guess its not supported.
There are other ways to get booting from GPT, involving shadow EFI bootloaders and a shadow MBR. Most of this was developed for the 'hackintosh' scene but it should would fine for booting CentOS from huge drives. Look for the Chameleon boot loader. You'll need to use gdisk to set the correct GPT GUID for the Linux partitions to make Chameleon boot. Since you're not necessarily wanting to boot XNU as well as CentOS, you wouldn't need the full Chameleon; the simpler PCEFI or something like that would work fine, and you wouldn't need (nor want) the whole /Extra thing that is used to boot XNU on generic PC hardware.
I haven't tried it, but single-booting CentOS 6 on one of those bootloaders should work as well as dual-booting XNU and Linux from Chameleon and similar fake EFI bootloaders works (many have done this; see the insanelymac and infinitemac sites for more info).