I have a pretty complicated configuration. I'm trying to be synthetic :
I have 4 disks (1 ssd, 2 nvme and 1 HDD) and 4 OSs (3 Win10 and 1 ubuntu) :
- Nvme 1 (Win10-1 + Ubuntu 20.04) /dev/nvme0n1
- Nvme 2 (Win10-2) /dev/nvme1n1
- HDD 1 (just data+swap) /dev/sda
- SSD 1 (Win10-3) /dev/sdb
The computer is UEFI.
At the begining I had no problem. Grub showed my 4 boot options.
But I had to reinstall Win10-1 and then I completly lost my grub. So I was able to boot only on Win10-1 or Win10-2 via windows boot manager.
I tried to repair Grub booting on a live ubuntu, but with mitigated succes... Here the actual behaviour :
Boot
|_______Grub
|______*Ubuntu > boots Ubuntu
|______*Windows Boot manager on /dev/nvme1n1
|_______Windows Boot Manager GUI
|______*Win10-1 > boots Win10-1
|______*Win10-2
|_______Grub
|______*Ubuntu > Grub rescue
|______*Windows Boot manager on /dev/nvme1n1 > boots Win10-2
So its perfect mess to me and by the way I lost the ability to boot on Win10-3...
I don't know how to erase this messy boot config in the MBRs and roll back to this:
Boot
|_______Grub
|______*Ubuntu > boots Ubuntu
|______*Windows Boot manager on /dev/nvme0n1 > boots Win10-1
|______*Windows Boot manager on /dev/nvme1n1 > boots Win10-2
|______*Windows Boot manager on /dev/sdb > boots Win10-3
Is there a magic tool to configure this?
Any help/advice will be apreciated.
---Edit 1--- Thanks for your answer WaterOfDark.
I already gone through this process but with no luck.
In addition, Win3 is not a big deal as I can boot it using EFI selection. I also have 3 EFI partition, on Nvme1, Nvme2 and SSD1
Maybe the issue is from those partitions? Maybe I can reset in some way the content of the EFI part and then run update-grub again?
I must admit that I'm not really at ease with the EFI stuff.
---Edit2---
I confirm Windows Fast Start up is disable
---Edit3---
Here are the result of commands : Here are the results
willy@Ubuntu:~$ sudo efibootmgr
BootCurrent: 0002
Timeout: 1 seconds
BootOrder: 0002,000A,0000,0008,0006,000B,0007
Boot0000* Windows Boot Manager
Boot0002* ubuntu
Boot0006* UEFI: SAMSUNG SSD 830 Series, Partition 2
Boot0007* UEFI: Sabrent Rocket 4.0 1TB, Partition 1
Boot0008* Windows Boot Manager
Boot000A* ubuntu
Boot000B* UEFI OS
willy@Ubuntu:~$ sudo dmidecode -t0 | grep -Ei "BIOS boot|UEFI"
BIOS boot specification is supported
UEFI is supported
boot-repair
first thing.