= EFI Unified Kernel Image Maker :proj-name: efi-mkuki :gh-name: jirutka/{proj-name} :version: 0.1.0

{proj-name} is a simple script for creating an https://systemd.io/BOOT_LOADER_SPECIFICATION/[EFI Unified Kernel Image] footnote:[It has been specified by the systemd (read as SystemDisaster) project, but you don’t have to use systemd-boot or any other systemd component to get the benefits of Unified Kernel Image.] -- a single EFI PE executable combining an EFI stub loader, a kernel image (vmlinuz), the kernel command line, and optionally an initramfs image, CPU microcode update, and a splash image.

Unified Kernel Image is basically an EFI application with all the components necessary for booting Linux directly from UEFI instead of relying on a bootloader. This image can be easily signed for Secure Boot.

To learn more about Secure Boot and why signing just a kernel image (when you use initramfs) is not sufficient, I recomend reading https://wiki.archlinux.org/title/Unified_Extensible_Firmware_Interface/Secure_Boot[Secure Boot on Arch Linux Wiki].

== Requirements

• http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html[POSIX-sh] compatible shell (e.g. Busybox ash, dash, ZSH, bash, …)
• cat, grep, sed, tr (BSD, Busybox or GNU)
• objcopy from https://www.gnu.org/software/binutils/[GNU binutils]
• EFI stub for your machine architecture from https://cgit.freedesktop.org/gummiboot/tree/?id=2bcd919c681c952eb867ef1bdb458f1bc49c2d55[gummiboot] footnote:[Gummiboot is referred to as obsolete because it was absorbed by systemd. Gummiboot EFI stubs are still useful though. You can download source tarball https://dev.alpinelinux.org/archive/gummiboot/gummiboot-48.1.tar.gz[gummiboot-48.1.tar.gz] (ff9a1632a82b1bef3434718e2aadca8783943f59) from Alpine Linux Archive.] or systemd

== Installation

=== On Alpine Linux

Install package https://pkgs.alpinelinux.org/packages?name={proj-name}[{proj-name}] on Alpine Linux v3.15 or later:

[source, sh, subs="+attributes"] apk add {proj-name}

=== On Arch Linux

Install package https://aur.archlinux.org/packages/{proj-name}[{proj-name}] from AUR:

[source, sh, subs="+attributes"] yay -S {proj-name}

Or use another AUR helper.

Please note that I’m not maintainer of this package.

=== From Tarball

[source, sh, subs="+attributes"] wget https://github.com/{gh-name}/archive/v{version}/{proj-name}-{version}.tar.gz tar -xzf {proj-name}-{version}.tar.gz cd {proj-name}-{version} make install DESTDIR=/ prefix=/usr/local

...or just download the link:https://raw.githubusercontent.com/{gh-name}/master/{proj-name}[{proj-name}] script directly.

NOTE: {proj-name} expects EFI stubs in /usr/lib/gummiboot. This can be rewritten to another path via EFISTUB_DIR variable passed to make install. If /usr/lib/systemd/boot/efi/ directory exists, make install will use it automatically.

== Usage

See the help section in link:{proj-name}#L3[{proj-name}] (or run {proj-name} -h).

== Resources

• https://wiki.archlinux.org/title/Unified_Extensible_Firmware_Interface/Secure_Boot[Unified Extensible Firmware Interface/Secure Boot] on Arch Linux Wiki
• https://wiki.gentoo.org/wiki/User:Sakaki/Sakaki%27s_EFI_Install_Guide/Configuring_Secure_Boot[Sakaki’s EFI Install Guide/Configuring Secure Boot] on Gentoo Wiki

== License

This project is licensed under http://opensource.org/licenses/MIT/[MIT License]. For the full text of the license, see the link:LICENSE[LICENSE] file.