Arch Linux

proudmuslim

Member

Registered: 2020-04-12

Posts: 21

GRUB not locating windows 10

Hey,

I installed Arch yesterday and am getting everything set up today. However, I've noticed that running grub-mkconfig -o /boot/grub/grub.cfg only detects Linux images, even with ntfs-3g and os-prober installed, and all partitions mounted.

Edit: Here is a list of my SSD Partitions

Root: /dev/sda1
Windows: /dev/sda2
Home: /dev/sda3
EFI: /dev/sda4

Last edited by proudmuslim (2020-04-12 14:39:21)

Head_on_a_Stick

Member

From: The Wirral

Registered: 2014-02-20

Posts: 9,003

Website

Re: GRUB not locating windows 10

Salam.

First mount the ESP:

# mount /dev/sda4 /mnt

Then check if Windows' bootloader is there:

find /mnt -name bootmgfw.efi

EDIT: cut to the chase...

Last edited by Head_on_a_Stick (2020-04-12 18:33:11)

---

Jin, Jîyan, Azadî

proudmuslim

Member

Registered: 2020-04-12

Posts: 21

Re: GRUB not locating windows 10

Salam.

First mount the ESP:

# mount /dev/sda4 /mnt

Then check if Windows' bootloader is there:

find /mnt -name bootmgfw.efi

EDIT: cut to the chase...

Wa Alaikum As Salam,
It mounts just fine, however running

 find /mnt -name bootmgfw.efi 

returns nothing

Last edited by proudmuslim (2020-04-12 20:41:54)

Slithery

Administrator

From: Norfolk, UK

Registered: 2013-12-01

Posts: 5,776

Re: GRUB not locating windows 10

Did you format the EFI partition when installing Arch and wipe all of the Windows boot files?

---

No, it didn't "fix" anything. It just shifted the brokeness one space to the right. - jasonwryan
Closing -- for deletion; Banning -- for muppetry. - jasonwryan

aur - dotfiles

proudmuslim

Member

Registered: 2020-04-12

Posts: 21

Re: GRUB not locating windows 10

Did you format the EFI partition when installing Arch and wipe all of the Windows boot files?

I did format the EFI partition, however I was unaware that it may contain windows boot files. Does this mean that I should reinstall windows and then restore grub?

Head_on_a_Stick

Member

From: The Wirral

Registered: 2014-02-20

Posts: 9,003

Website

Re: GRUB not locating windows 10

You might not have to reinstall Windows if it's just the bootloader that's been wiped. For example: https://www.diskpart.com/windows-10/rep … oader.html

And you probably won't have to restore GRUB afterwards, just run this command from an Administrator prompt in Windows' powershell [sic]:

bcdedit /set "{bootmgr}" path "\EFI\GRUB\grubx64.efi"

^ That will change the Windows NVRAM entry to point to Arch's GRUB bootloader, change the path if you used something other than GRUB for the --bootloader-id= option when you ran the grub-install(8) command during installation.

---

Jin, Jîyan, Azadî

proudmuslim

Member

Registered: 2020-04-12

Posts: 21

Re: GRUB not locating windows 10

You might not have to reinstall Windows if it's just the bootloader that's been wiped. For example: https://www.diskpart.com/windows-10/rep … oader.html

And you probably won't have to restore GRUB afterwards, just run this command from an Administrator prompt in Windows' powershell [sic]:

bcdedit /set "{bootmgr}" path "\EFI\GRUB\grubx64.efi"

^ That will change the Windows NVRAM entry to point to Arch's GRUB bootloader, change the path if you used something other than GRUB for the --bootloader-id= option when you ran the grub-install(8) command during installation.

Great, thank you! Fortunately I set my bootloader ID to grub during install so that's a little less hassle

proudmuslim

Member

Registered: 2020-04-12

Posts: 21

Re: GRUB not locating windows 10

You might not have to reinstall Windows if it's just the bootloader that's been wiped. For example: https://www.diskpart.com/windows-10/rep … oader.html

And you probably won't have to restore GRUB afterwards, just run this command from an Administrator prompt in Windows' powershell [sic]:

bcdedit /set "{bootmgr}" path "\EFI\GRUB\grubx64.efi"

^ That will change the Windows NVRAM entry to point to Arch's GRUB bootloader, change the path if you used something other than GRUB for the --bootloader-id= option when you ran the grub-install(8) command during installation.

Small hiccup, I assumed that windows 10 was installed in EFI mode because that's how it usually goes, however a bit more digging showed me that Windows 10 is on an MBR partition table, not GPT. Should I reinstall grub for i386-pc?

Slithery

Administrator

From: Norfolk, UK

Registered: 2013-12-01

Posts: 5,776

Re: GRUB not locating windows 10

Does your motherboard support booting from GPT partitions in BIOS mode? Many of them don't.

---

No, it didn't "fix" anything. It just shifted the brokeness one space to the right. - jasonwryan
Closing -- for deletion; Banning -- for muppetry. - jasonwryan

aur - dotfiles

proudmuslim

Member

Registered: 2020-04-12

Posts: 21

Re: GRUB not locating windows 10

Does your motherboard support booting from GPT partitions in BIOS mode? Many of them don't.

doubtful, as to double check I went to go reinstall windows and it told me it was unable to install an EFI system on that partition. My motherboard is a mid-range b450 board [ASRock B450m Pro4], so I doubt it'll have too many bells and whistles like that

Head_on_a_Stick

Member

From: The Wirral

Registered: 2014-02-20

Posts: 9,003

Website

Re: GRUB not locating windows 10

What partition table is this? If Windows was installed in non-UEFI mode then it must have been an MS-DOS partition table.

# parted /dev/sda print

If the "Partition Table" is listed as "msdos" then just go ahead and reinstall GRUB in non-UEFI mode. Disable UEFI and enable "Legacy" mode (CSM) to reboot into the non-UEFI system.

If you have a GUID partition table ("gpt") then you will need to add a BIOS boot partition to hold GRUB's core.img, use type "ef02" in gdisk (no filesystem). I use sectors 34-2047, they should be free if the disk is correctly aligned but that may not be the case if Windows has messed it up.

---

Jin, Jîyan, Azadî

proudmuslim

Member

Registered: 2020-04-12

Posts: 21

Re: GRUB not locating windows 10

What partition table is this? If Windows was installed in non-UEFI mode then it must have been an MS-DOS partition table.

# parted /dev/sda print

If the "Partition Table" is listed as "msdos" then just go ahead and reinstall GRUB in non-UEFI mode. Disable UEFI and enable "Legacy" mode (CSM) to reboot into the non-UEFI system.

If you have a GUID partition table ("gpt") then you will need to add a BIOS boot partition to hold GRUB's core.img, use type "ef02" in gdisk (no filesystem). I use sectors 34-2047, they should be free if the disk is correctly aligned but that may not be the case if Windows has messed it up.

 Model: ATA SATA SSD (scsi)
Disk /dev/sda: 120GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start   End     Size    Type     File system  Flags
 4      1049kB  538MB   537MB   primary  fat32
 2      608MB   67.6GB  67.0GB  primary  ntfs
 1      67.6GB  99.8GB  32.2GB  primary  ext4
 3      99.8GB  120GB   20.2GB  primary  ext4
 

  It's msdos, guess I'll go reinstall grub, thanks. I think I have legacy boot already enabled because Manjaro booted with i386 just fine when I replaced grub there before installing arch, but I'll double check.

Thanks for your help!