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CachyOS

Boot Manager Configuration

systemd-boot

systemd-boot has two kinds of configuration files, one for systemd-boot itself in /boot/loader/loader.conf and one for each individual kernel entry in /boot/loader/entry.

Loader configuration

In this configuration file, you can change the default entry and the timeout of systemd-boot

/boot/loader/loader.conf
default @saved
timeout 5
#console-mode keep # This option configures the resolution of the console.

Kernel Commandline Configuration

We provide a tool for easier configuration of systemd-boot sdboot-manage. One of the perks of this tool is global kernel commandline configuration. The configuration file for sdboot-manage is located in /etc/sdboot-manage.conf. Edit the LINUX_OPTIONS= line in /etc/sdboot-manage.conf to change kernel parameters.

/etc/sdboot-manage.conf
LINUX_OPTIONS="zswap.enabled=0 nowatchdog quiet splash"

After making changes, regenerate all systemd-boot entries with the following command

Terminal window
❯ sudo sdboot-manage gen

rEFInd

Like systemd-boot, rEFInd has two configuration files. refind.conf located in boot/efi/EFI/refind is mainly for changing how rEFind behaves while /boot/refind_linux.conf is for managing your boot options. refind.conf contains extensive comments explaining all its options.

Kernel Commandline Configuration

To pass kernel parameters to the commandline, modify “Boot using default options” in /boot/refind_linux.conf

/boot/refind_linux.conf
"Boot using default options"     "root=PARTUUID=1cb353ec-7f03-4820-8b4b-03baf53a208f rw zswap.enabled=0 nowatchdog quiet splash"

Changes to both configuration files will immediately take effect. Running a command to “save” changes is unnecessary.

GRUB

Unlike systemd-boot and rEFInd, GRUB only has one configuration file located in /etc/default/grub. There is pretty good documentation in this file that explains what each option does.

Hiding the GRUB Boot Menu

To hide the GRUB menu, simply set these following options accordingly.

/etc/default/grub
GRUB_TIMEOUT='0'
GRUB_TIMEOUT_STYLE=hidden

Press ESC to get access to the GRUB prompt. From here run normal or exit to get back to the familiar GRUB boot menu.

Kernel Commandline Configuration

To pass kernel parameters to the commandline with GRUB, we need to edit GRUB_CMDLINE_LINUX_DEFAULT within /etc/default/grub

/etc/default/grub
GRUB_CMDLINE_LINUX_DEFAULT='nowatchdog zswap.enabled=0 quiet splash'

Every time we modify the GRUB configuration file, we need to remake the config with the following command

Terminal window
❯ sudo grub-mkconfig -o /boot/grub/grub.cfg

Limine

Limine is a modern bootloader known for its simple configuration. This guide covers the basics to get you started.

Configuration primarily happens in /boot/limine.conf (or sometimes in the EFI system partition) for menu settings and /etc/default/limine for kernel parameters.

Boot Menu Configuration

This file controls the boot menu’s behavior and appearance. Changes made here take effect immediately after saving – no extra commands are needed.

  • Timeout: Sets how many seconds Limine waits before automatically booting the default entry.
    /boot/limine.conf
    timeout: 5
  • Default Entry: Specifies which menu entry boots by default. Entries are numbered starting from 1. If not set, the default value is 1.
    /boot/limine.conf
    default_entry: 2 # Boot the second entry by default

Example (/boot/limine.conf):

/boot/limine.conf
timeout: 5
default_entry: 2 # Points directly to the 'linux-cachyos' entry below


/+CachyOS        # Entry 1: A directory (use /+ to expand by default)
//linux-cachyos  # Entry 2: The actual bootable entry
    protocol: linux
    kernel_path: boot():/vmlinuz-linux-cachyos
    cmdline: quiet splash root=UUID=... rw # Basic kernel parameters
    module_path: boot():/initramfs-linux-cachyos.img

Theming

You can customize the visual appearance of the Limine boot menu:

  • Wallpaper: Set a background image. Supported formats include BMP, PNG, and JPEG.
    /boot/limine.conf
    wallpaper: boot():/splash.png
    wallpaper_style: stretched # Options: 'stretched', 'tiled', 'centered'
    backdrop: 000000           # Background color (RRGGBB hex) if style is 'centered'
  • Fonts: Use a custom font file and adjust its size.
    /boot/limine.conf
    term_font: boot():/custom_font.F16
    term_font_scale: 2x2 # Scales font size, useful for high-resolution displays
  • Colors: Modify terminal text and background colors.
    /boot/limine.conf
    term_background: 80000000 # Example: Semi-transparent black (AARRGGBB)
    # Other color options like term_foreground, etc., are available.

Kernel Command Configuration

On CachyOS, kernel entries in the Limine boot menu are automatically managed. When you install or remove kernels, the limine-mkinitcpio-hook uses the limine-entry-tool utility in the background to update the boot entries.

While entries are handled automatically, you can configure the kernel parameters (also known as the kernel command line) that are passed to the kernel when it boots.

  1. Edit the configuration file: Modify the KERNEL_CMDLINE variables in /etc/default/limine. You can set default parameters for all kernels or specific parameters for certain kernel names (e.g., linux-cachyos).
    /etc/default/limine
    # Default parameters for most kernels
    KERNEL_CMDLINE[default]="quiet splash rd.udev.log_priority=3"
    

    # Specific parameters for the 'linux-cachyos' kernel
    KERNEL_CMDLINE["linux-cachyos"]="quiet splash mitigations=off"
    

    # Parameters for fallback entries (if generated)
    # KERNEL_CMDLINE[fallback]="..."
  2. Apply the changes: After saving /etc/default/limine, you need to regenerate your initramfs images and update the Limine entries to apply the new kernel parameters. Run the following command:
    Terminal window
    sudo limine-mkinitcpio
    This command triggers the mkinitcpio process, which includes the limine-mkinitcpio-hook, ensuring your changes in /etc/default/limine are incorporated into the boot entries at /boot/limine.conf.

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