recent kernel upgrades damage mbr

Mikkel L. Ellertson mikkel at infinity-ltd.com
Tue Jun 17 18:49:36 UTC 2008


Gene Heskett wrote:
> On Tuesday 17 June 2008, M A Young wrote:
>> On Tue, 17 Jun 2008, Maurizio Marini wrote:
>>> I would advice any list member that it is in the wild a issue regarding
>>> grub and mbr.
>> I don't know if this is relevant, but F8 grub (unless the latest update
>> has been written to the boot sector) can't cope with filesystems created
>> on F9 because of the inode size change. So it is definitely a good idea to
>> upgrade grub if you are upgrading.
>>
>> 	Michael Young
> 
> Which may be a good idea, Michael, but does this require the silent re-writing 
> of the mbr to accomplish this?  For existing, already setup and working drives, 
> I don't think so.
> 
Yes, it does require re-writing the MBR. This is because Grub stage 
1 is in the MBR, and it needs to know where on the disk Grub stage 
1.5 is. When you upgrade Grub, the location changes. Stage 1.5 is 
the part of Grub that know how to read file systems, and can then 
load the rest of Grub. Remember, all stage 1 can do is load a chunk 
of code from a specific location on the disk, and the location is 
part of the code stored in the MBR when you install/upgrade Grub. 
Why would you think that upgrading the boot loader would not 
re-write the MBR?

Mikkel
-- 

   Do not meddle in the affairs of dragons,
for thou art crunchy and taste good with Ketchup!

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