I have a Macbook Pro 5,2 and I've had a sporadic problem with having to reinstall GRUB after a system update. This has happened with several of the recent versions of Ubuntu, although I don't have an exact record of which ones.
Every once in a while, after a system update with the update manager, I can no longer boot into Ubuntu unless I repair the GRUB installation manually. To do that I follow this procedure:
by following the instructions under ChRoot. That always works to reinstall things, but as you can imagine, it's not my favorite thing to do and takes about a half hour each time.
One problem I run into when trying to follow those instructions is that when I get to step #11 where I am supposed to run
grub-install /dev/sda, it always tells me that I cannot execute that command because it would have to use "blocklists" which are inherently unstable, and the the only way to proceed is to use the
--force option on grub-install. So I use the
--force option and it does install it, but the fact that it does not go according to the instructions has me concerned that perhaps that is the source of the instability that the warning is telling me about. But it won't let me reinstall it any other way.
As background information I might mention as background that I have Refit installed on the Mac side, in case that is a source of the problem because it's conflicting with or fighting with Grub over the boot sector or something like that. I also have not been able to boot into OS/X from Grub even though it's on the Grub startup menu. It just hangs and does nothing if I select that. In order to boot into OS/X I have to use the hardware support on the Mac by pressing the option key while it's booting and then selecting the OS/X partition, which then boots via Refit. Conversely I cannot boot into Ubuntu via Refit even though that partition shows up on the Refit menu (as a Windows partition because I think Refit assumes anything that isn't OS/X is "Windows"). Finally here is the output of
sudo fdisk -l for my system:
WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util fdisk doesn't support GPT. Use GNU Parted. Disk /dev/sda: 500.1 GB, 500107862016 bytes 255 heads, 63 sectors/track, 60801 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000001 Device Boot Start End Blocks Id System /dev/sda1 1 26 204819+ ee GPT /dev/sda2 * 26 12972 103986412 af HFS / HFS+ /dev/sda3 12972 25767 102782192 83 Linux /dev/sda4 25768 59272 269128912 83 Linux
OSX is installed on sda2. The linux root is installed on sda3 and my /home folder is on sda4. The entire Macbook Pro dual boot process is a bit of a mystery to me, so I am including as much information as I can in case some of it is useful. Thanks in advance for any help.