GRUB doesn't boot all kernels

Ralf Mardorf silver.bullet at zoho.com
Thu Jul 14 10:30:54 UTC 2016


On Thu, 14 Jul 2016 17:49:18 +1000, blind Pete wrote:
>It is easy to lose track of which installation, and bootloader, has 
>control of the mbr.  Then you have to remember to rewrite the mbr 
>from the correct installation so that the expected binaries and 
>configuration files are found and acted upon.

No install has got a boot loader installed. I have a special partition
just for the boot loader that isn't related to any OS install I use. 

>Is the command to write to the mbr "grub-install"?

It is.

>Interesting partially working things happen when the last thing 
>that wrote to the mbr was not the thing that you thought was 
>the last thing to write to the mbr.

Nothing but Ubuntu could automatically write to the MBR.
All my installs are tailored minimalist installs. Arch Linux by default
is minimalist, KISS, e.g. no package ever would enable a service, an
ISO installs just core components, no Ubuntu install media provides
such a minimalist install. Anyway, I installed a most minimalist
Ubuntu and disabled auto-enabled services and removed software, e.g.
the bootloader, just the do-release-upgrade reinstalled it.

Btw. I'm using BIOS, nothing else is provided by my machine.

>I'm clutching at straws here.  Have you considered; file corruptions,
>a broken intrd, maybe the that version of grub does not know about the 
>very latest version of ext4?

Xenial's GRUB boots another kernel, from the same ext4 partition.
Actually there was an issue during the do-release-upgrade regarding
sda1 and the freebsd-ufs.

>Try writing something to the mbr of all of your drives, or unplug the
>drive(s) that you think are not involved.

I restored the MBR from a backup and run grub-install.
I purged the kerneal and delete the packages and will build a new
kernel soon.

>[snip]
>> [root at moonstudio weremouse]# grep Grub2 -A2 /tmp/boot.txt  
>>  => Grub2 (v1.99) is installed in the MBR of /dev/sda and looks at
>> sector 1 of
>>     the same hard drive for core.img. core.img is at this location
>> and looks in partition 97 for .  
>
>Partition 97?  

 1 /dev/sda1
 2 /dev/sda2
 3 /dev/sda5
 4 /dev/sda6
 5 /dev/sda7
 6 /dev/sda8
 7 /dev/sda9
 8 /dev/sda10
 9 /dev/sda11
10 /dev/sda12
11 /dev/sda13
12 /dev/sda14 
13 /dev/sdb1
14 /dev/sdb2
15 /dev/sdb5
16 /dev/sdb6
17 /dev/sdb7
18 /dev/sdb8
19 /dev/sdb9
20 /dev/sdb10
21 /dev/sdb11
22 /dev/sdb12
23 /dev/sdb13
24 /dev/sdb14
25 /dev/sdb15

We could close this thread. It's not solved, but not worth to waste
more time with it.

Regards,
Ralf




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