Arch Linux

Roken

Member

From: South Wales, UK

Registered: 2012-01-16

Posts: 1,253

I know not Arch per se, but converting Windows boot

Don't hate me for this, but I can't find an answer.

Arch is my primary desktop, 7 days per week. Some time ago, I accidentally wiped a 1GB HD in my system, and so though I'd chuck Windows 10 on it, as a just in case thing. At the time, Arch was BIOS boot, and so that's how I installed Windows.

After an unfortunate incident with Arch, I re-installed to EFI boot. Arch is fine, and booting from an NvME drive.

I can still boot Windows by selecting the boot drive in BIOS, but can't add it to GRUB.

I know that Windows can be converted to EFI, but my concern is that it will overwrite EFI on the NvME drive, which I want to avoid (I don't want to have to fix up GRUB again).

Now, since Windows is on a dedicated drive, can I safeley boot Windows, convert to EFI, then reboot (without any boot modification) back to Arch and grub-update to add it to the GRUB menu, or will it kill my NvME EFI installation leaving me with a fix on my hands.

If I can't do it, meh! but if I can, bonus.

---

Ryzen 5900X 12 core/24 thread - RTX 3090 FE 24 Gb, Asus Prime B450 Plus, 32Gb Corsair DDR4, Cooler Master N300 chassis, 5 HD (1 NvME PCI, 4SSD) + 1 x optical.
Linux user #545703

Lone_Wolf

Member

From: Netherlands, Europe

Registered: 2005-10-04

Posts: 11,911

Re: I know not Arch per se, but converting Windows boot

Looks like MS created "Microsoft MBR2GPT command line tool" for just such purpose .

Official doc : https://docs.microsoft.com/en-us/window … mbr-to-gpt
3rd party guide https://www.windowscentral.com/how-conv … windows-10

---

Disliking systemd intensely, but not satisfied with alternatives so focusing on taming systemd.

(A works at time B)  && (time C > time B ) ≠  (A works at time C)

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 21,659

Re: I know not Arch per se, but converting Windows boot

Most remotely sane implementations that touch the ESP will only touch the files they need (as does Windows by default) if you're afraid that whatever conversion utility you use here (... afaik just dumping Windows EFI boot binaries with bcfg or however it's called does really just adjust the files, but I've only hands oned that once a few years ago) will overwrite any contents, back up whatever you have on the ESP so you can dump it back on in doubt. The worst that can happen is that the NVRAM entries are wiped which can easily be reinstated with a grub-install from a chroot.