# 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
```sh
git clone https://github.com/koopa1338/kernel-builder
cd kernel-builder
cargo install --path .
```
or install it with cargo install from crates.io
```sh
cargo install kernel-builder
```
You also need a `config.toml` with the needed paths configured in `$HOME/.config/kernel-builder/config.toml`:
```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
| `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:
```sh
KB_KERNEL=/boot/efi/vmlinuz-linux-lts kernel-builder
```
### CLI Options
```sh
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`:
```sh
# 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:
```sh
emerge @kernels
```
And `emerge -u @world` won't touch kernel sources.
### Option 2: Exclude from Depclean
Add to `/etc/portage/make.conf`:
```sh
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.