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Issue: installer/grub when using separate /boot (noformat)

PostPosted: Jul 28th, '21, 01:22
by zeebra
Issues with Mageia installer/grub when using an existing and seperate /boot partition and not formating it during installation.
Howdy, this will sound idiotic, because I don't remember HOW it failed exactly and with what error message, but I'm fairly confident this problem can be reproduced consistently (hopefully not just by me). It affects Mageia 7 and Mageia 8 AT LEAST (maybe6?).. If my memory serves me right, this issue was introduced with the new Mageia installer (UEFI/Mageia6?)..

Issue: A new installation of Mageia will fail to boot after installation if you install it with a previously used /boot partition without formatting it.
Note on boot settings: legacy BIOS/traditional using a separate /boot partition

This issue is the same if /boot partition is only used by Mageia or by several distroes. Installing Mageia and using a seperate and previously used /boot partition will create conditions where a new and fresh installation of Mageia will fail to boot. If you during Mageia installation format the separate /boot partition booting the newly installed Mageia will succeed.

Just a guess.. As far as I remember Grub fails to find the Kernel and can't boot. Edit. I think perhaps Grub fails to install at all and the old grub remains

So, I can't fairly remember when I first had this issue, but I did have it with Mageia 7. I didn't understand this isse back then or how I "solved" it, but I had it several times (yes, I installed Mageia 7 several times). This issue came back to me when I moved from Mageia 7 to Mageia 8. Installing Mageia 8, it failed to boot, but then I by instinct remember that if I format the /boot partition, it should boot. And guess what, it did! This leads me to think this issue is not just me, but an issue with the installer in Mageia 7 and Mageia 8, for people who use a separate /boot partition. Not many people do that these days, sure, but some do.

Steps to reproduce:
- Use a laptop with lagacy BIOS option set in UEFI
- Install Mageia with /boot and encrypted / (and /home), this installation will work!
- Install Mageia again with the same partition setup, but only format / --- this installation should fail to boot

Not sure the encrypted part is relevant, but I added it just in case. You could probably reproduce it without using encrypted / as well.

Re: Issue: installer/grub when using separate /boot (noforma

PostPosted: Jul 28th, '21, 18:13
by doktor5000
Can you mention any use case where it would make sense to reinstall, format / but not a separate /boot partition? Sorry but that doesn't make sense to me.

Re: Issue: installer/grub when using separate /boot (noforma

PostPosted: Jul 29th, '21, 01:31
by zeebra
doktor5000 wrote:Can you mention any use case where it would make sense to reinstall, format / but not a separate /boot partition? Sorry but that doesn't make sense to me.


That's just an example to reproduce the issue.

But this issue would show up for example if you have Mageia 7 installed, then procede to install Mageia 8 without formating /boot, for those who install from cd/usb instead of using the upgrade path. Or any reinstall of Mageia 7/7, 7/8, 8/8 to / for whatever reason.

Or did you mean /boot? Is it abnormal to not format /boot if you use a seperate /boot partition?

Re: Issue: installer/grub when using separate /boot (noforma

PostPosted: Jul 29th, '21, 18:42
by doktor5000
zeebra wrote:Is it abnormal to not format /boot if you use a seperate /boot partition?

Yes. How do you ensure that what's in the /boot partition matches what you install afterwards?

Re: Issue: installer/grub when using separate /boot (noforma

PostPosted: Jul 30th, '21, 05:03
by zeebra
Can you further explain your reasoning? I'm not exactly sure what you mean. What about matching?

I've not had problems using a separate and persistent /boot partition before and sharing this between several distroes. What tends to happen is that the distro just adds the Kernel image and files and replace/update the grub files/folders. Not sure how that is an issue. For Mageia, is it not basically the same thing to do regular updates (with kernel) = add a new kernel and update grub in an existing setup and /boot? Is that not what one should expect to happen during an installation as well?

What exactly is Mageia doing with /boot during an installation? Is it doing some unexpected magic?

Re: Issue: installer/grub when using separate /boot (noforma

PostPosted: Jul 30th, '21, 16:44
by doktor5000
For one, sharing a /boot partition between distros is not a good idea in the first place. How do you "share" bootloader configuration among distros? Sorry but that's a recipe for disaster and not a valid use case.

Feel free to go ahead with that and raise a bug report if you wish, but it still doesn't make sense.

Re: Issue: installer/grub when using separate /boot (noforma

PostPosted: Jul 30th, '21, 23:45
by zeebra
Well, the bootloader can be a bit impractical, especially with distroes that insist on installing one. But generally you let one distro control the bootloader.
But, are you saying that /boot always has to be formatted && that it cannot be shared between distroes (which it can't if it has to be formatted)? I don't see how that is so when it just bascally contains a bunch of Kernel images and the bootloader files. It's not a magic partition that does something special. Not counting the bootloader files it's entirely static.

I've never had any disasters with such a setup, in fact, it has rather helped me avoid disasters and get me out of some other disasters. I'm not going to file a bug report if you don't think it's a valid use case. But I would add that this kind of setup always worked prior to the new installer (that was with Mageia 6 if I remember right).

A seperate /boot is a bit abnormal in the first place, ok. And I don't depend on it or have to have it, but.. Are you saying if you have 2 or 3 distroes with a seperate /boot, that you should create 3 partitions just for /boot, one for each of them? That seems like more potential for disaster as far as I am concerned.

I'm aways interested in your take on things, so please let's go into details if you don't mind.

Re: Issue: installer/grub when using separate /boot (noforma

PostPosted: Jul 31st, '21, 17:58
by doktor5000
zeebra wrote:Are you saying if you have 2 or 3 distroes with a seperate /boot, that you should create 3 partitions just for /boot, one for each of them?

Why do you use a separate /boot partition in the first place ? And in general if you use multiple distros, have the bootloader for each of those installed in their / partition, and keep only one "master" bootloader which chainloads the others, that way you don't mix up bootloader configuration.
BTW you also use separate / partitions for multiple distros, and there's also no potential for disaster from that.

But if you need or want to use a separate /boot partition, then yes you should have one for each of them. Keep in mind that generated bootloader configuration is also stored below /boot and you cannot share those.
Each distro has specific kernel / boot options or quirks, and keeping only one /boot for several distros can break of lot of stuff and introduce additional issues.