Ubuntu
grub package

grub error 18 after upgrade to 8.04

Asked by LouiseR

I have been running both 7.04 and XP (dual-boot) happily on my laptop pretty much since 7.04 came out. I finally took the decision to upgrade the ubuntu bit to the latest version (8.04) so went through the upgrade manager process to get to 7.10 (no problems, went remarkably smoothly) and then took the next step to upgrade to 8.04.

The upgrade process appeared to go fine. However, after the obligatory reboot at the end of the upgrade, I get a grub error 18 before getting to the point of choosing to boot into ubuntu or XP.

Is there anything I can do to resolve this or am I going to have to rebuild the machine?

Thanks and Regards,
Louise.

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Bhavani Shankar (bhavi) said : 		#1

Hello Lousie

Below is a link with more details on the same

http://wiki.linuxquestions.org/wiki/GRUB#Error_18

Regards

Bhavani Shankar.

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LouiseR (louise-renwick) said : 		#2

I don't understand why this should be an issue now when I haven't changed anything other than upgrading the OS. I never saw this issue with earlier versions of Ubuntu.

Is it fixable?

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Bhavani Shankar (bhavi) said : 		#3

hello yes

http://episteme.arstechnica.com/eve/forums/a/tpc/f/96509133/m/385000954831

http://episteme.arstechnica.com/eve/forums/a/tpc/f/96509133/m/305004889731

Hope it helps

Bhavani Shankar.

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LouiseR (louise-renwick) said : 		#4

thanks for the links, they explain what the issue is, but don't tell me why this is suddenly an issue now when this moring it was fine. I haven't changed any partition sizes - does the upgrade to 8.04 do that?

Now for the daft follow-up question...

How do I create a new boot partition if I can't get at my machine cos it won't boot?

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LouiseR (louise-renwick) said : 		#5

I changed a BIOS setting as per the following I got from the forums after much searching:

"It turns out the Thinkpad bios has an option to protect the special 4.5G setup non-partition at the end of the disk (Accessed under "Security" options). When set to "normal" this hides the last 4.5G of the disk. It seems Linux is not tricked by this, and sees the whole disk, so LILO and grub get installed with the whole disk geometry. However, when booting, LILO and grub use the BIOS, which reports the fake geometry minus the 4.5G, causing both LILO and grub to barf.

Setting the bios setting to "disabled" makes the bios geometry match the real geometry, allowing LILO or grub to boot..."

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Brendan (chexstix) said : 		#6

Can either of you explain to a very unsophisticated convert to Linux how I set the BIOS to 'disabled?'

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Brendan (chexstix) said : 		#7

Can either of you explain to a very unsophisticated convert to Linux how I set the BIOS to 'disabled?'

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Brendan (chexstix) said : 		#8

Can either of you explain to a very unsophisticated convert to Linux how I set the BIOS to 'disabled?'

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marcobra (Marco Braida) (marcobra) said : 		#9

We can try to helps with your BIOS if you tell us model and brand of your pc...?

Thank you

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Brendan (chexstix) said : 		#10

I reloaded version 8.04 and the problem hasn't surfaced. But, I have an IBM T41 ThinkPad.

And for what it's worth, this is a huge improvement over Windows 2000!