Universal Blue•4w ago

No Windows Boot option (CSM/Legacy BIOS)

Installed bazzite-nvidia and have lost the boot option for windows. After looking around I've tried the following: 1. ujust regenerate-grub This outputs the following, which is also missing finding the windows boot option

Generating grub configuration file ...
Adding boot menu entry for UEFI Firmware Settings ...
done

Generating grub configuration file ...
Adding boot menu entry for UEFI Firmware Settings ...
done

2. Checking if I've accidentally deleted the windows boot partition. I was trying to be very careful about this, and i can still see all the partitions windows had from before i installed.

sda      8:0    0 931.5G  0 disk 
├─sda1   8:1    0    50M  0 part /var/home/<user>/mnt/sda1
├─sda2   8:2    0 805.9G  0 part 
├─sda3   8:3    0   100M  0 part /var/home/<user>/mnt/sda3
├─sda4   8:4    0   517M  0 part /var/home/<user>/mnt/sda4
...(bazzite partitions)...

sda      8:0    0 931.5G  0 disk 
├─sda1   8:1    0    50M  0 part /var/home/<user>/mnt/sda1
├─sda2   8:2    0 805.9G  0 part 
├─sda3   8:3    0   100M  0 part /var/home/<user>/mnt/sda3
├─sda4   8:4    0   517M  0 part /var/home/<user>/mnt/sda4
...(bazzite partitions)...

Also, I've mounted some of the partitions and can see Windows files

<user>@bazzite:~/mnt/sda3/EFI/Microsoft/Boot$ ls *.efi
bootmgfw.efi  bootmgr.efi  memtest.efi  SecureBootRecovery.efi

<user>@bazzite:~/mnt/sda3/EFI/Microsoft/Boot$ ls *.efi
bootmgfw.efi  bootmgr.efi  memtest.efi  SecureBootRecovery.efi

Also some boot looking things in sda1

<user>@bazzite:~/mnt/sda1$ ls
'$RECYCLE.BIN'   bootmgr   BOOTNXT   BOOTSECT.BAK   Recovery   Recovery.txt  'System Volume Information'

<user>@bazzite:~/mnt/sda1$ ls
'$RECYCLE.BIN'   bootmgr   BOOTNXT   BOOTSECT.BAK   Recovery   Recovery.txt  'System Volume Information'

I'm not sure what else to check, anyone have any further ideas?

Solution:

So the issue (i believe) was I had left CSM/Legacy BIOS enabled without realising it and bazzite installed non-efi. Because windows was EFI it was not visible in the non-efi grub menu. Updating the BIOS so that i could disable CSM/Legacy BIOS (and Secure Boot which was also not present in my earlier bios version) meant i could reinstall bazzite using grub-efi....

Jump to solution

89 Replies

yogsodoth•4w ago

Have you tried manually creating a grub entry for it? https://unix.stackexchange.com/questions/758353/resolving-dual-boot-issue-windows-not-showing-in-grub-menu

Unix & Linux Stack Exchange

Resolving Dual-Boot Issue: Windows Not Showing in GRUB Menu

I recently encountered a dual-boot issue on my Debian 12 system where Windows 10 was not showing up in the GRUB menu after a Debian update. I spent some time troubleshooting the problem and was abl...

adumer•4w ago

I have not, will give that a go I added this to my /etc/grub.d/40_custom, because as far as I could see the boot files were on /dev/sda3. Then ran ujust regenerate-grub

menuentry "Windows 10" {
    insmod ntfs
    set root=(hd0,3)  
    chainloader +1
}

menuentry "Windows 10" {
    insmod ntfs
    set root=(hd0,3)  
    chainloader +1
}

Can see the new entry, but selecting it does not boot

Linus Xu•4w ago

I’m pretty sure +1 is not intended for EFI Just checked that my os-prober-generated Windows entry looks like this:

menuentry 'Windows Boot Manager (on /dev/nvme0n1p1)' --class windows --class os $menuentry_id_option 'osprober-efi-[redacted]' {
    insmod part_gpt
    insmod fat
    search --no-floppy --fs-uuid --set=root [redacted]
    chainloader /EFI/Microsoft/Boot/bootmgfw.efi
}

adumer•4w ago

That makes more sense, the sda3 partition i have is not ntfs either so don't think i need insmod ntfs Under the [redacted] i'm assuming is a file-system uuid? Do you know how to find that for building this menu entry myself?

Linus Xu•4w ago

Something like lsblk or blkid The two should be the same and for FAT fses it should be only 8 characters

adumer•4w ago

Found it, thank you

<user>@bazzite:~$ lsblk -o NAME,UUID
NAME   UUID
sda    
...
├─sda3 XXXX-XXXX
...

<user>@bazzite:~$ lsblk -o NAME,UUID
NAME   UUID
sda    
...
├─sda3 XXXX-XXXX
...

Ah damn 😦 getting error: ../../grub-core/loader/i386/pc/chainloader.c:213:invalid signature I had to convert from the MBR to UEFI boot mode in windows to get bazzite installed originally, but it looks like sda1 has the old MBR boot stuff. Potentially that's confusing it? This seems like a problem

<user>@bazzite:~$ ls /sys/firmware
acpi  dmi  memmap

<user>@bazzite:~$ ls /sys/firmware
acpi  dmi  memmap

Missing efi

TeamLinux01•4w ago

Does efibootmgr show the Windows boot entry any more?

asen23•4w ago

is csm enabled in bios?

adumer•4w ago

efibootmgr outputs EFI variables are not supported on this system. How can i check this, i looked in my bios recently and it has "Both Legacy and UEFI" option selected currently. I can quickly boot and grab the correct property name

TeamLinux01•4w ago

Makes me think that CSM was used to install the system, if it is saying EFI variables are not supported.

asen23•4w ago

what is your motherboard?

adumer•4w ago

asen23•4w ago

disable legacy that is csm i believe

adumer•4w ago

asus p8z77-v pro

TeamLinux01•4w ago

I agree, disable legacy

Gaming

Programming

No Windows Boot option (CSM/Legacy BIOS)