Grub2 problem - can only boot to 2 of 3 OS's

[jim]

On 5/29/20 6:51 AM, Liam Proven wrote:
> On Fri, 29 May 2020 at 04:48, jim <jf_byrnes at comcast.net> wrote:
>>
>> I had a system with Mint18.3 and Ubuntu18 installed. I had 100GB of free
>> space at the end of the disk. I decided I wanted to install mint19.3 in
>> the free space. I booted from the Mint19.3 install dvd. I used gparted
>> to shrink the Ubuntu partition so I ended up with about 195GB of free
>> space. I then had gparted create a new partition in the free space and
>> installed Mint19.3.
>>
>> This is my configuration:
>>
>> Partition 1 = sda1 - Ubuntu18
>>
>> Partition 2 (extended) = sda6 - Mint18.3
>>                            sda5 - swap
>>
>> Partition 3 = sda3 - Mint19.3
> 
> 2 questions.
> 
> [1] Presumably you have an MBR-format disk, if you have an extended partition.


> So, if it's there, why not just make another logical partition for
> Mint 19.3? It would be easier and cleaner.

I haven't done this in a while and did not think it would cause any 
problems.
> 
> [2] When you installed the new distro, where did you tell it to
> install its bootloader, do you know?

I'm not sure the installation "asked me", but when I partitioned I chose 
/. Frankly I was sort of on autopilot, I made the choices I remember 
making other times.

> I think you may now have 2 or 3 copies of GRUB. 1 for Ubuntu, one for
> Mint 18.3, one for Mint 19.3.
> 
> If you pick one to be the "master" -- i.e. the main one, for the OS
> you use the most -- you can move the others by telling them to install
> GRUB into their root partition(s), not into the MBR.
> 
> Boot the relevant non-master OS, say off /dev/sda5, and run
> 
> $ sudo grub-install /dev/sda5
> 
> or if off /dev/sda3:
> 
> $ sudo grub-install /dev/sda3

I tried this from both sda1 - Ubuntu 18.4 and sda3 - Mint18.3 and got 
this result both times:

~$ sudo grub-install /dev/sda1
[sudo] password for jfb:
Installing for i386-pc platform.
grub-install: warning: File system `ext2' doesn't support embedding.
grub-install: warning: Embedding is not possible.  GRUB can only be 
installed in this setup by using blocklists.  However, blocklists are 
UNRELIABLE and their use is discouraged..
grub-install: error: will not proceed with blocklists.

This error puzzles me because using the Disks utility all of them are 
reported as Ext4(Version 1.0).

> This means that they won't fight over the MBR.
> 
> On the main OS, boot it up as normal, _check you have mounted the root
> drives of *all* OSes_ then run
> 
> $ sudo update-grub
> 
> It _should_ detect the others and add them to its menu.
> 
> You need to do this every time you update any of the OSes.
> 
> So if you boot Mint 19, update Mint 19, then to use the new kernel, you need to
> 
> #1 Reboot into Ubuntu
> #2 Mount all partitions
> #3 Update Ubuntu's copy of Grub
> #4 Reboot _again_
> #5 Now you can reboot into updated Mint

Doing this still donsn't work. I can see where it says it detects 
Mint18.3 but it never shows up in the grub menu. My goal is to boot to 
Mint18.3 that is my main OS, the move to Mint19.3 was to be gradual as I 
moved stuff over to it.

> Yes it is a minor PITA but it's easier than switching to a whole new
> boot manager, IMHO.
> 
> rEFInd won't work on a BIOS machine, AFAIK. I have only tried it on
> Macs and although it worked, I found it a pain to deal with.
> 

Thanks,  Jim