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I don't know what happened to cause this.

I have Snow Leopard, Ubuntu 11.04 Natty Narwhal and Windows XP SP3 on my early 2006 MacBook Pro. It is a Core Duo unit, NOT Core 2 Duo, so it is 32-bit only - Model Identifier MacBookPro1,1. I use rEFIt 0.14 for my boot menu.

For some reason neither XP nor Ubuntu would boot anymore. I'd just get a black screen with a rapidly flashing underscore in the top-left corner.

Having both those OSes failing to boot suggested a problem with the boot loader in my MBR. The rEFIT partition tool verified that my MBR partitions were still synced with my GPT partitions, so I rewrote my MBR partition table with fdisk while booted from Parted Magic:

# fdisk /dev/sda

(fdisk warns about the disk having a GPT. I press on anyway.)


(Print the existing partition table to make sure it's OK.)


(Write the old partition table back to disk. This also writes a new MBR boot loader.)

After this XP would boot but Ubuntu would not, with the same symptom. Now I used update-grub while chrooted into Ubuntu from Parted Magic:

# mount /dev/sda3 /mnt
# mount --bind /dev /mnt/dev
# mount --bind /sys /mnt/sys
# mount --bind /proc /mnt/proc
# chroot /mnt

Chroot issues some warnings about not being able to identify some group IDs. I don't know why that happens, or whether it is a problem.

At this point while I am still booted off of Parted Magic's kernel, I am running from Natty's filesystem.

# update-grub

Update-grub detects each of my operating systems then claims to complete successfully, but still won't boot.

I asked this same question over at rEFIt's Sourceforge support forum but there have been no replies yet. I also Googled quite a bit, and see many who have the same black screen problem, but none of their situations seem quite like mine.

Thanks for any help you can give me. -- Don Quixote

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up vote 2 down vote accepted

Ah, I need to run grub-install rather than update-grub.

Some googling around for documentation yielded the insight that update-grub just writes a new configuration file. What I've been trying to do is to put a new boot loader into the beginning of my Ubuntu partition.

I have the following partitions:

/dev/sda1 EFI FAt (Empty; required by UEFI Spec)
/dev/sda2 HFS+ Mac OS X Snow Leopard
/dev/sda3 ext4 Ubuntu 11.04 
/dev/sda4 NTFS Windows XP

The following would run to completion and report success when I booted from the Parted Magic Live CD:

# mount /dev/sda3 /mnt
# mount --bind /proc /mnt/proc
# mount --bind /sys /mnt/sys
# mount --bind /dev /mnt/dev
# chroot /mnt
# /usr/sbin/update-grub /dev/sda3     ### THIS IS INCORRECT

The correct command seems at first to be:

# /usr/sbin/grub-install /dev/sda3

However, grub warns about installing onto a partition with blocklists, which it does not want to do. I give it the "--force" option:

# /usr/sbin/grub-install --force /dev/sda3

After this, Ubuntu 11.04 boots just fine; I am running it now.

GNU Grub Manual 1.99

Installing Grub Using grub-install

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Immediately after offering the bounty I managed to answer my own question. Can I either undo the bounty, or award it to myself? – Michael Crawford Oct 10 '11 at 20:58
not normally (…) - however flag the answer and ask the moderators. – fossfreedom Oct 12 '11 at 20:10

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