Boot Configuration (modules/core/boot/default.nix)

The default.nix file located at modules/core/boot/default.nix manages the foundational boot settings for your nixri system. This file handles everything from kernel parameters and filesystems to the bootloader setup and AppImage support.

Structure

The file defines several settings nested under the boot configuration attribute:

1. Filesystems and Basic Boot Settings

This section outlines support for different filesystems and temporary file handling.

  • supportedFilesystems: Ensures the system can interact with multiple disk formats, including ntfs, exfat, ext4, fat32, and btrfs.
  • tmp.cleanOnBoot: A boolean (true) indicating that the temporary directory (/tmp) will be cleaned every time the system boots.

2. Kernel Configuration

This section defines the core Linux kernel to be used along with specific parameters to tune system performance.

  • kernelPackages: Specifies the Linux kernel to use. By default, this is set to the Zen kernel (pkgs.linuxPackages_zen) which is optimized for desktop usage and responsiveness. Other options include _latest, _hardened, _rt, etc.
  • kernel.sysctl: Sets sysctl variables. Here, vm.swappiness is set to 100, which is often tuned for setups using zRAM to maximize memory compression efficiency.
  • kernelParams: Defines arguments passed to the kernel at boot. Currently, it uses "preempt=full" to prioritize lower latency at the expense of slight throughput reductions—ideal for desktop and gaming environments.

3. Bootloader (systemd-boot & EFI)

This configuration uses systemd-boot as the primary lightweight bootloader and explicitly disables GRUB.

  • loader.systemd-boot:
    • enable: Set to true to use systemd-boot.
    • consoleMode: Set to "auto" to automatically scale up the text and resolution during boot based on your hardware display.
  • loader.efi:
    • canTouchEfiVariables: Set to true, allowing the installation process to seamlessly modify EFI boot variables.
    • efiSysMountPoint: Mounts the EFI partition precisely at /boot.
  • loader.timeout: Sets the boot menu display duration to 10 seconds, giving you ample time to select alternative generations if needed.
  • loader.grub:
    • enable: Set explicitly to false to prevent bootloader conflicts.

4. AppImage Support

This section registers a binary format (binfmt) to allow AppImages to run seamlessly.

  • binfmt.registrations.appimage: Configures the kernel to recognize the AppImage magic bytes (\x7fELF....AI\x02) and automatically execute them using the ${pkgs.appimage-run}/bin/appimage-run interpreter. This means you can simply execute AppImages without needing to prefix them with a runner command.

How to Apply Changes

Changes made to this file require a system rebuild. If you alter critical boot settings (like the bootloader or kernel), it is highly recommended to run the rebuild script and verify the output for any errors before rebooting your machine.