Arch Linux

joanmanel

Member

Registered: 2012-11-06

Posts: 250

Easiest way to change legacy boot to UEFI? (dual boot with W10)

Hi There,

The computer I am using now, I installed Windows and Arch Linux using legacy boot around 10 years ago. Since then I have re-installed the OSs a few times (and I have changed most of the hardware), but I always kept it with legacy boot (it was the easiest if another OS is already installed with legacy boot).

But during the last couple of years I have been having more and more problems with legacy boot. For example a new MoBo was giving me problems. And for example I cannot update W10 to W11.

So I am thinking about swapping to UEFI. I wonder what would be the easiest way of doing this. On one hand, updating it in ArchLinux, but also not disrupting W10.

Thanks

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,258

Re: Easiest way to change legacy boot to UEFI? (dual boot with W10)

Are Windows and Arch on the same disk or are these separate? If they are separate then whatever changes you'd do on Arch wouldn't necessarily affect Windows and vice versa and you could convert one at a time and use your MBs bootloader for switching OS

The biggest adjustment will be how you're reorganizing your partition setup, you should create an ESP of minimally 100MB (assuming Window's EFI files should be there as well) , will likely have to shrink at least one partition/filesystem to be doing so and convert the disk to GPT format if it isn't yet (not sure how Windows on MBR would react to that to be frank), you should have a backup of stuff you can't afford to lose and I'd strongly reccommend you use a Gparted Live Disk for the partitioning process as doing this manually on the cli can be hairy and is prone to missing steps (like you need to shrink your FS first before doing the partition and there are no real unified cli tools that do both)

After that for Arch, boot a live disk in EFI mode, mount and chroot into your real system,  decide whether your kernel images should live on the ESP or as they currently are (?) on your normal root partition, if the former you'd mount the new ESP  to /boot  (move kernel images over from your root beforehand), install your bootloader on the EFI partition according to it's documentation, if the latter you'd mount the ESP somewhere else e.g. /efi and install a bootloader that can read your kernels off of your root like GRUB or refind.

Lone_Wolf

Administrator

From: Netherlands, Europe

Registered: 2005-10-04

Posts: 15,149

Re: Easiest way to change legacy boot to UEFI? (dual boot with W10)

Incase both Oses are booting from the same disk you're kinda screwed and may need to do a fresh install of windows..

Microsoft does have official tools to switch windows10 from legacy bios boot to uefi boot, but they won't work for dual-booting systems.

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

clean chroot building not flexible enough ?
Try clean chroot manager by graysky