Kernel Builder

The Kernel Builder is a application written in rust that scans for available kernel sources in a configured directory and allows you to select which kernel to build, as well as install the modules, copy the compiled kernel to the boot partition, as well as generating the necessary initramfs.

Prerequisites

Basic knowledge of kernel configuration and compilation
to use the initramfs generation you have to enable the dracut feature and dracut has to be installed on your system

Installation

git clone https://github.com/koopa1338/kernel-builder
cd kernel-builder
cargo install --path .

or install it with cargo install from crates.io

cargo install kernel-builder

You also need a config.toml with the needed paths configured in $HOME/.config/kernel-builder/config.toml:

kernel = "/boot/vmlinuz-linux"
initramfs = "/boot/initramfs-linux.img" # Optional, only needed if `dracut` feature is enabled
kernel-config = "/usr/src/.config"
kernel-src = "/usr/src"
keep-last-kernel = true           # Optional, backup current kernel before installing new one
last-kernel-suffix = "last"      # Optional, suffix for backup kernel (default: "last")
cleanup-keep-count = 3             # Optional, cleanup old kernels keeping N newest + current

Configuration Options

Option	Type	Default	Description
`kernel`	Path	Required	Path to install the kernel image
`initramfs`	Path	Optional	Path for initramfs (requires `dracut` feature)
`kernel-config`	Path	Required	Path to your kernel `.config` file
`kernel-src`	Path	Required	Directory containing kernel sources
`keep-last-kernel`	bool	`false`	Backup current kernel before installing new one
`last-kernel-suffix`	string	`"last"`	Suffix for backed up kernel
`cleanup-keep-count`	number	Optional	Cleanup old kernels keeping N newest + current
`verbose`	bool	`false`	Enable debug logging (via `--verbose` CLI flag)

Usage

If correctly setup you should just run kernel-builder, it should ask for root permission if not already run as root. You can override options by setting environment variables prefixed with KB_. For example to override the kernel path:

KB_KERNEL=/boot/efi/vmlinuz-linux-lts kernel-builder

CLI Options

kernel-builder [OPTIONS]

Options:
  -v, --verbose      Enable debug logging
      --no-build     Skip kernel build
      --no-modules   Skip installing kernel modules
      --no-initramfs Skip generating initramfs (requires `dracut` feature)
      --menuconfig   Open menuconfig before building
      --replace      Replace current kernel without backup
  -h, --help        Print help
  -V, --version     Print version

Gentoo Configuration

Since kernel-builder manages kernel sources in /usr/src, you may want to prevent Portage from automatically removing old kernel sources during emerge --depclean.

Option 1: Use Portage Sets (Recommended)

Create a portage set to manage kernel sources separately from @world:

# Create the sets directory and file
mkdir -p /etc/portage/sets
echo "sys-kernel/gentoo-sources" > /etc/portage/sets/kernels

Now update kernel sources with:

emerge @kernels

And emerge -u @world won't touch kernel sources.

Option 2: Exclude from Depclean

Add to /etc/portage/make.conf:

EMERGE_DEFAULT_OPTS="--exclude sys-kernel/gentoo-sources"

This prevents emerge --depclean from removing any gentoo-sources version.

Combined Approach (Most Control)

Use both options above for maximum control:

emerge -u @world updates everything except kernel sources
emerge @kernels updates kernel sources when you decide
emerge --depclean won't touch kernel sources

Contributing

There is still room for improvements, so if you would like to contribute to the project, please feel free to submit a pull request or open an issue.

License

This script is released under the EUPL License. See the LICENSE file for more information.

kernel-builder 0.7.2