Boot configuration

The prism.hardware.boot option tells your system how to handle the handoff from your computer's hardware (firmware) to the Linux kernel. Getting this right is essential for a successful build.

Modern PCs (UEFI)

If your computer was made in the last 10 years, it almost certainly uses UEFI. This mode uses systemd-boot, which is fast, minimal, and integrates perfectly with NixOS.

prism.hardware.boot.mode = "uefi";
# Optional: Change the mount point if your EFI partition isn't /boot
# prism.hardware.boot.efiMount = "/boot/efi";

Virtual Machines or old PCs (Legacy/BIOS)

If you are running Prism inside a Virtual Machine (like QEMU/KVM without UEFI enabled) or on much older hardware, you should use Legacy mode. This uses the GRUB bootloader.

prism.hardware.boot.mode = "legacy";
# Optional: Specify the disk for the bootloader if it's not /dev/sda
# prism.hardware.boot.device = "/dev/nvme0n1";

Which one should I choose?

If you are unsure which mode your hardware supports, you can check while booted into the Prism ISO:

  1. Open a terminal.
  2. Run: ls /sys/firmware/efi
  3. If the directory exists: Use uefi.
  4. If it doesn't exist: Use legacy.

Advanced boot tweaks

For advanced users who need to modify kernel parameters (e.g., for silent boot or troubleshooting), you should add them to the standard NixOS boot options within your module block:

( { ... }: {
  boot.kernelParams = [ "quiet" "splash" "nvidia-drm.modeset=1" ];
  
  # Set the timeout for the boot menu (in seconds)
  boot.loader.timeout = 5;
})

Note on partitioning

  • UEFI requires a dedicated EFI Partition (usually FAT32, flagged as esp).
  • Legacy usually installs the bootloader to the MBR (Master Boot Record) of the drive.