need help updating GRUB -ubuntu 20.04 LTS

[oldfred]

Did you say what brand/model system?

Some other users have posted that system seems to be UEFI only. Not sure if then user could not find setting, as some seem to hide it or not.
Lenovo announced all 2020 products will be UEFI only (UEFI Class 3 or no CSM).
https://support.lenovo.com/us/en/sol...-2020-products

But if you were able to boot installer in BIOS mode, I would think you could boot an install in BIOS mode.

[unknowable]

Once they are both in proper booting order "UEFI" they both will show up>>>Windows&Buntu in grub.
I would now>> if i were you is just install eOS in UEFI mode.

Hm. I checked my iso of eOS, and it's just named "elementaryos-6.0-stable.20211005.iso". I was sure it was x64, but the boot partitions I'm sure are MBR only. It looks like that's my answer. I guess now I have to figure out how to do that.

Oh, now that I look at the eOS install page, it specifically tells you how to install in EFI mode. Looks like I have some work ahead of me. Good thing I've kept good notes on everything I've done. Thanks for your help!

[unknowable]

....

But if you were able to boot installer in BIOS mode, I would think you could boot an install in BIOS mode.

I just used the Boot Menu to boot from the USB thumb drive that I had installed the installation OS to. Hm. Lots of reading to do....

[unknowable]

Did you say what brand/model system?

Oh sorry, no I didn't. I'm using an HP/Compaq Elite 8300. According to System Settings, it's a "Quad-Core Intel® Core™ i5-3470 CPU @ 3.20GHz". Does that help at all?

[oldfred]

Conversion from MBR to gpt will erase drive, so if you have any other data on drive, be sure to have good backups.
There are tools to convert MBR to gpt without erasing data (backups still required). But full reinstall of grub and edit of anyplace like fstab with UUIDs has to be manually edited as change creates new UUIDs. Conversion better for data only drives. New install often easier.

How you boot install media from UEFI boot menu is then how it installs.
So your UEFI boot menu for the USB flash drive should have two entries.
But some tools like Rufus make either UEFI only or BIOS only installers.

[1fallen]

But if you were able to boot installer in BIOS mode, I would think you could boot an install in BIOS mode.

GRUB can't switch between these two boot modes, at least to my knowledge.
OP can boot to both windows and eOS, just wants grub to pick them both up.

[unknowable]

Conversion from MBR to gpt will erase drive, so if you have any other data on drive, be sure to have good backups.
There are tools to convert MBR to gpt without erasing data (backups still required). But full reinstall of grub and edit of anyplace like fstab with UUIDs has to be manually edited as change creates new UUIDs. Conversion better for data only drives. New install often easier.

Hm. Well I image the entire drive every night using Clonezilla, so I have some decent backups. I don't know if I can just reinstall one partition though, my home directory. I have some research to do...

How you boot install media from UEFI boot menu is then how it installs.
So your UEFI boot menu for the USB flash drive should have two entries.
But some tools like Rufus make either UEFI only or BIOS only installers.

Yah, I think I was trying out Kubuntu when I installed elementary OS, so I was able to use Etcher. I don't know what it does. Looks like I should just boot the Clonezilla USB iso and see if it will reinstall just one partition. If it does, then I can reinstall eOS as EFI, and use Clonezilla to rebuild just the home directory's partition. Hmm.

[unknowable]

GRUB can't switch between these two boot modes, at least to my knowledge.
OP can boot to both windows and eOS, just wants grub to pick them both up.

Yes, that's basically correct. If I don't do anything on bootup, it goes straight into windows with no choices. If I hit the Boot Menu key, it gives me lots of choices, like for every drive I have. Because of what you say - GRUB can't switch between two boot modes - I need to reinstall eOS as EFI, according to the way they instruct on the eOS website.

[1fallen]

If it does, then I can reinstall eOS as EFI, and use Clonezilla to rebuild just the home directory's partition. Hmm.

That's quite advanced, probably easier and less stressful to just re-install in UEFI, the learning curve is beneficial. IMHO
missed the part "Home Only" very do-able.

[unknowable]

That's quite advanced, probably easier and less stressful to just re-install in UEFI, the learning curve is beneficial. IMHO
missed the part "Home Only" very do-able.

Ok then that should be as easy as it sounds, assuming Clonezilla will let me reinstall only selected partitions. I'm sure it will do that, I just need to research it. Great! Does that mean that if I reinstall eOS as EFI, then use Clonezilla (if it will do this) to reimage just the home directory, that all my programs and settings and things will still be in place? Boy, that would be awesome! That's just like an hour of work, and that's nothing. If it works that way. If it might be able to do that, I really need to back up one more time, which will take 3 hours, but it will save me a lot of trouble as compared to reinstalling everything. Yes, research. Thank you.