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luciusican

Member

Registered: 2023-01-31

Posts: 3

[Solved] Grub does not detect Windows

Hello, good morning. I am writing because I have encountered the following problem, I can boot to Windows from the BIOS selector but I have not been able to get it to appear in the GRUB list.

The thing is that when I installed Arch on my notebook, I have not had any problem using "os-prover" as it has detected it.

But on my desktop computer, I have linux on a SDD and Windows on a HDD. Therefore I have not combined the partitions "efi". Using "os-prover" and adding the command line at the end of the grub to detect systems has not helped to solve the problem.

I have read that mounting the windows partitions and reusing grub-mkconfig has not solved my problem either.

What could I be doing wrong?

Attached is the list: sda1 is the windows efi partition, sda2 is the windows system partition (disk c:), and sda3 is simply a data partition.

[lucifer@Xcution ~]$ lsblk -f
NAME   FSTYPE FSVER LABEL           UUID                                 FSAVAIL FSUSE% MOUNTPOINTS
sda                                                                                     
├─sda1 ntfs         System Reserved 983035703035570A                                    
├─sda2 ntfs         Sistema         C4463AFC463AEEB4                                    
└─sda3 ntfs         Datos           6FBA8D292CCC05DE                                    
sdb                                                                                     
└─sdb1 ntfs         HDD - Lucius    28200A39200A0E8E                       47.5G    95% /mnt/windows-ntfs
sdc                                                                                     
├─sdc1 vfat   FAT32                 E0E4-B8D2                            1021.8M     0% /boot/efi
├─sdc2 ext4   1.0                   960d84fe-2978-4b4f-b158-a6d4717312e9   56.8G    37% /
├─sdc3 ext4   1.0                   06d691e0-4201-4a3d-81f0-532930f2a7c6  244.3G    22% /home
└─sdc4 swap   1                     dbc9bd87-566d-4308-9f25-9e2567e195bb                [SWAP]

Last edited by luciusican (2023-01-31 17:09:26)

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 24,094

Re: [Solved] Grub does not detect Windows

If your windows is booting in BIOS mode but your Linux is booting in UEFI mode you cannot chainload the BIOS Windows from an UEFI GRUB installation. You'd have to make Windows boot in EFI mode as well but there are Windows tutorials for that. Your /dev/sda1 is not the EFI partition (it would/should be FAT as well) but a system reserved partition which are not the same thing.

Last edited by V1del (2023-01-31 01:27:38)

luciusican

Member

Registered: 2023-01-31

Posts: 3

Re: [Solved] Grub does not detect Windows

If your windows is booting in BIOS mode but your Linux is booting in UEFI mode you cannot chainload the BIOS Windows from an UEFI GRUB installation. You'd have to make Windows boot in EFI mode as well but there are Windows tutorials for that. Your /dev/sda1 is not the EFI partition (it would/should be FAT as well) but a system reserved partition which are not the same thing.

Thanks for the quick response, I will take a look at the new information you just told me, then I will comment with an update. Best regards.

Edit 31/01/2023: My partition was definitely in MBR mode, the first tutorial I found to change it to EFI worked. After that I rebuilt the grub configuration file, and it has detected it automatically (Even without mounting it). As a subsequent act after switching back to EFI windows, I had to reorder the BIOS settings to reorder the boot of the systems because it put back as priority the windows one, I had to leave the arch linux one first again. After that, no problems.

Solved.

Last edited by luciusican (2023-01-31 17:10:03)