Re: GRUB2 (packaged with Ubuntu 12.10) won't boot OS X

[Alex Kanavin]

2012/11/8 Chris Murphy <address@hidden>:

> Well that's debatable, because it's inherently fragile to depend on NVRAM for 
> this. "Zapping the PRAM" is a common (if not sometimes mystical)
> troubleshooting technique on Macs, and the instant you do this your computer 
> cannot be made to revert to the behavior you now have. So it's not only
> fragile, but it's obscured, and also it's basically broken your ability to 
> boot the primary OS: OS X.

Why can't it be reverted? If Ubuntu's installation used efibootmgr to
write to NVRAM, so can I, via some recovery USB stick:
address@hidden:~$ sudo efibootmgr -v
BootCurrent: 0000
BootOrder: 0000,0080
Boot0000* ubuntu
HD(1,28,64000,00003a7c-4c02-0000-e14b-00002d290000)File(\EFI\ubuntu\grubx64.efi)
Boot0080* Mac OS X
ACPI(a0341d0,0)PCI(b,0)03120a00000000000000HD(2,64028,2538aa60,00001f31-428b-0000-880b-0000d21d0000)
BootFFFF*     MM(b,ffcb4000,ffffbfff)H.D...

Oh and I'm able to boot OS X just fine via pressing option and then
choosing OS X from rEFInd (and if I didn't have rEFInd, I'm sure OS X
would then boot directly). What I'm trying to troubleshoot here is
GRUB's inability to boot OS X either through the generated script
(that does some magic with OS X kernel) or through chainloading, which
does seem like a GRUB's bug.

> Weird. The Windows option is hard wired and requires three things to be true: 
> the first 440 bytes of the MBR contain boot loader code, the MBR contains 
> more than one entry, one of the entries other than the first entry in the MBR 
> has an active flag set.
>
> So something has done those three things. The Windows options is the gateway 
> to the Apple EFI activating the CSM-BIOS, so that would seem to indicate 
> you're booting CSM-BIOS, but the fact it's a dead end with "no operating 
> system" rather than going to GRUB possibly means you're booting EFI, in which 
> case why do you have a hybrid MBR, and code in the MBR bootloader region.
>
> What do you get for:
>
> dmesg | grep -i efi

That is attached.

Alexander

dmesg-efi.txt
Description: Text document