Drop BIOS Support and only build UEFI images, as T3 is now in the free tier

[andre4ik3]

It would be nice to support UEFI images as well as BIOS ones. Because from what I understand the firmware type is baked into the AMI, and it's impossible to pick it manually or change it after the instance is created.

Currently, to run a UEFI NixOS EC2 instance, I have to first install Amazon Linux (the only AMI I could find that is UEFI), disable monitoring and allow SSH access, then use nixos-anywhere to install NixOS and reboot into it.

[arianvp]

There is EFI support?

Just set ec2.efi = true; and the resulting image will be registered as an UEFI image on upload

[arianvp]

The aarch64 images are already EFI as it's the only thing that supported by Amazon. So this is definitely working.

I did think of moving the x86 image that we upload to the NIXOS AWS account from legacy-bios to uefi-preferred image type by default though. Then if you have both an MBR and a GPT the default image works both on nitro and non-nitro ec2 instances.

There was some blocker for that though. I don't remember exactly what it was.

[andre4ik3]

There is EFI support?

Just set ec2.efi = true; and the resulting image will be registered as an UEFI image on upload

Oh nice! But that requires generating your own images? (I'm looking to do this anyway to try to skip running disko) It would be nice to have preuploaded UEFI images :)

[arianvp]

Great news. Amazon now has t3 as the default free tier instance instead of t2 which means the free tier now supports UEFI. We will be dropping BIOS support. I'll pick this up for 26.05

Source: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-free-tier-usage.html

[arianvp]

Need to come up with a migration plan for existing instances. But that probably means people having to force opt in to GRUB and BIOS with a lib.mkForce

[philiptaron]

Hey Arian, what's it take to implement this?