arch: add script to generate UKIs

[c3Ls1US]

Currently, booster does not support generating Universal Kernel Images (UKIs) natively and this PR allows creating UKIs via ukify on Arch Linux.

To generate UKIs, we can simply delegate the functionality to external tools such as ukify. The resulting binaries are currently stored in /boot/Linux/EFI and manual intervention would be required from the user to configure the appropriate boot loader configution files to load the binary by default. Otherwise, binaries would probably need to be selected at boot time. For instance, in systemd-boot, loader.conf should be modified.

[anatol]

Thank you! I am sure a lot of people find UKI functionality useful.

Could you please add a section to the documentation (https://github.com/anatol/booster/blob/master/docs/manpage.md) about what is UKI and how to use booster with it?

[anatol]

Looks great, thank you!

[c3Ls1US]

No problem. Also, one thing to consider is that the result is written to /boot/Linux/EFI by default.

Some users have a separate partition (e.g. /efi) where they boot EFI executables, which is a problem. Arch Linux also assumes /efi by default in its own initrd generator. For flexibility, I'm considering of changing it so a boot path is required to pass to the script.

[anatol]

Sounds good.

Let me know once you are done developing the PR and I move with merging it.

[c3Ls1US]

@anatol let me know if you prefer squashing my commits.

[anatol]

I will squash the commits before merging

[c3Ls1US]

Finished

This PR closes #110 and potentially #79 if there are no plans for a native UKI implementation

[Zile995]

@c3Ls1US @anatol

Or you can simply use the booster-ukify or booster-um.