Installation of Ubuntu on a Windows desktop

[alan44zz]

Sorry, I don't understand anything

[alan44zz]

> GRUB_DISABLE_OS_PROBER=false

Ok

grub-update : OK, windows entry has been added.

Yes ubuntu is on gpt disk.

Then I put the Ubuntu disk to boot first.


Reboot = Neither Grub nor windows, but error message saying Windows is corrupted ?!

That means that now I cannot even boot to Ubuntu at all...

I put back the Windows disk first. Reboot.

When I try to enter Ubuntu (EasyBCD choice...) I got this as told yesterday:



So it seems there's something to fix in the grub ...

[tea for one]

Your disk arrangement is complicated and still using old-fashioned Legacy installations and extended partitions.
I hope that you would consider oldfred's comments in post 10.
In essence, back up your data, start from scratch using modern UEFI and GPT.
One disk for Windows 10/11 and a separate disk for Ubuntu 24.04.
Grub would manage both very easily if you wish.
Even easier if you only want Ubuntu (as you mentioned in post 5)
More robust and future proof.

[tea for one]

Yes ubuntu is on gpt disk.

According to the boot-repair report, Ubuntu is located at:-
Line 142 - OS#3: Ubuntu 24.04.1 LTS on sdb6
Line 166 - sdb : notGPT

[yancek]

The image you posted in post 12 clearly shows GRUB4DOS which is windows software and NOT Grub. Since you booted that after running EasyBCD I guess that would be expected.

Reboot = Neither Grub nor windows, but error message saying Windows is corrupted ?!

When you set the Ubuntu drive (sdb) to first boot priority this is what you get? Does that mean you do not see the Ubuntu Grub menu? I would not expect you to see the windows is corrupted message until you have selected windows from the boot menu. This drive is unusual as you have only one primary partition on it and that is used to hold logical partitions including a large windows partition before the Ubuntu partition. Note the last line in boot repair. I don't know if changing that would resolve the issue. I would expect that since you have Ubuntu Grub code in the MBR of sdb where Ubuntu is installed that you would at least be able to see and boot Ubuntu.

[alan44zz]

Well! First, thank you everybody for your replies.

Yesterday I decided to go UEFI, converted all disks to GPT. And began problems with the OS disk... Converted through Partition Master, ok. But impossible to boot in UEFI with this GPT disk... Reverted to MBR, LEGACY boot, and also impossible to boot ! The windows repair disk couldnt repair anything Well, finally I could repair manually, ok now Win is working. But Ubuntu isn't booting anymore.

As I am for sure not able to repair myself I will wipe the Ubuntu disk and install it again, as before. If dual boot doesn't work at once, I will not use it, will just change the BIOS details to boot Ubuntu or Win.

The question is: As I am stucked to LEGACY with my Windows (Win 10 LBTS), how must I prepare the disk for Ubuntu ? MBR ? GPT ? If GPT, will it boot with LEGACY BIOS ?

And in Rufus to create the install USB, must I select MBR or GPT ?

Thank you !

[oldfred]

Windows requires gpt partitioning for UEFI boot.
Windows requires the very old MBR(msdos) partitioning for BIOS boot.
Ubuntu does not care either partitioning works with either boot mode, but it really should require gpt for UEFI.

With UEFI you must have an ESP - efi system partition, FAT32 with boot,esp flags. Only one per drive is allowed by most UEFI implementations. Windows & Ubuntu will share if dual booting on one drive.
Often better with multiple drives to use ESP on same drive as install, but installer normally defaults to first drive's ESP and will give errors if no ESP on first drive.

With BIOS boot on gpt Linux requires a tiny 1 or 2MB unformatted partition with bios_grub flag.

I used Ubuntu in BIOS mode on gpt starting in 2010. When first converting to UEFI, I put both an ESP & bios_grub on new drives. Only difference with UEFI & BIOS boot for Ubuntu is ESP & bios_grub partitions and version of grub. Or just reinstalling grub in other boot mode can convert an install.

Grub2 only boots working Windows. That means Windows cannot be hibernated nor need chkdsk. And Windows fast startup sets hibernation flag for a quicker boot. It also may turn fast startup back on with updates.

Normally you cannot dual boot with one system UEFI and other BIOS on same drive. But with multiple drives, it is possible to boot in different mode. Grub can only boot other installs in same boot mode, but you can always boot from UEFI/BIOS one time boot key, if boot loaders are on different drives.

Do not use grub4dos. Not sure how much it has been updated, but it is based on grub (legacy grub), not grub2. And grub2 became standard in 2010. We often call grub2 as grub as it is standard grub now.

[alan44zz]

Well, all is good now, installed Ubuntu as a "full wipe disk" install on its dedicated disk, then added the grub menu, it found windows, and all is working fine booting from the Ubuntu disk. Thank you everybody for helping, will probably have other questions later.