Arch Linux

asergio

Member

Registered: 2017-12-13

Posts: 9

Is it possible to boot Windows UEFI on Grub installed on a BIOS Arch?

I have reinstalled Windows this morning and now it won't boot via Grub (still boots if I change boot order on BIOS). I have trying making a lot a changes on my Grub configuration but everything returned an "invalid signature" error.

After some research I found what it was because Windows is now on UEFI mode, which Arch is not.
I have tried to answer the question for some hours but nothing that I read is really clear. What is the easiest way for me to make Grub dual-boot work again?

Thanks.

archimboldo

Member

Registered: 2016-03-07

Posts: 232

Re: Is it possible to boot Windows UEFI on Grub installed on a BIOS Arch?

https://wiki.archlinux.org/index.php/GR … menu_entry

---

Rules for problems.
Everyone has problems. Animals have problems. And buildings. And cats, and trees.
Problems are your friends. Treat them well.

asergio

Member

Registered: 2017-12-13

Posts: 9

Re: Is it possible to boot Windows UEFI on Grub installed on a BIOS Arch?

https://wiki.archlinux.org/index.php/GR … menu_entry

I did exactly that. I get invalid signature error.

nl6720

The Evil Wiki Admin

Registered: 2016-07-02

Posts: 595

Re: Is it possible to boot Windows UEFI on Grub installed on a BIOS Arch?

From the linked wiki page:

Note: This menuentry will work only in UEFI boot mode and only if the Windows bitness matches the UEFI bitness. It will not work in BIOS installed GRUB. See Dual boot with Windows#Windows UEFI vs BIOS limitations and Dual boot with Windows#Bootloader UEFI vs BIOS limitations for more information.

The easiest solution is to boot the Arch Linux installation medium in UEFI mode, mount the filesystems, arch-chroot in, mount the EFI system partition (also add it to fstab) and install GRUB for UEFI systems.

Last edited by nl6720 (2018-08-19 17:04:09)

asergio

Member

Registered: 2017-12-13

Posts: 9

Re: Is it possible to boot Windows UEFI on Grub installed on a BIOS Arch?

From the linked wiki page:

Note: This menuentry will work only in UEFI boot mode and only if the Windows bitness matches the UEFI bitness. It will not work in BIOS installed GRUB. See Dual boot with Windows#Windows UEFI vs BIOS limitations and Dual boot with Windows#Bootloader UEFI vs BIOS limitations for more information.

The easiest solution is to boot the Arch Linux installation medium in UEFI mode, mount the filesystems, arch-chroot in, mount the EFI system partition (also add it to fstab) and install GRUB for UEFI systems.

Any way you can give me more detail on how to do this? I am not fully understanding the procedure.

nl6720

The Evil Wiki Admin

Registered: 2016-07-02

Posts: 595

Re: Is it possible to boot Windows UEFI on Grub installed on a BIOS Arch?

To boot UEFI operating systems you must have a UEFI bootloader. To install GRUB for UEFI systems you need to be booted in UEFI mode (this is not really true, but otherwise you won't get a separate boot entry for GRUB). Since your Arch system boots in BIOS mode you need to use the Arch Linux installation medium to boot in UEFI mode.

Don't know if I can simplify it further:

1. Boot the live iso

2. mount your partitions exactly the same way you did when installing Arch

3. Chroot into the installed system with arch-chroot /mnt

4. Find the EFI system partition and mount it.

5. install GRUB